Re: Linker issues with struct postblit
On 10/29/21 7:10 AM, Stanislav Blinov wrote: On Friday, 29 October 2021 at 11:05:14 UTC, Imperatorn wrote: On Thursday, 28 October 2021 at 01:39:10 UTC, Thomas Gregory wrote: I am a maintainer of the [dhtslib](https://github.com/blachlylab/dhtslib) package and I have been running into issues with a new implementation of reference counting we are using. [...] Postblit? https://dlang.org/spec/struct.html#struct-postblit I imagine Imperatorn is quite familiar with postblit and was pointing out that it is strange to use postblit constructor, which is deprecated, in a "new implementation". The original post was long and really buried the lede, but OP was pointing out what looks like a compiler bug: a linker error referencing a postblit symbol only shows up when compiling with DMD or with LDC earlier than 1.25. Can someone give some insight?
Re: D equivalent to Rust or Scala's Optional and Result and best practice ?
On 10/18/21 12:03 PM, dangbinghoo wrote:
hi,
It seems that now we have `Optional` and `Result` packages in Dub, are
these enough or fully equal to Rust or Scala's error-handling and
pattern-matching?
if these are enough for real-code, any best practice advice?
thanks!
Not quite the same as tagged algebraic union ("sum type" == Rust enum)
are not (yet?) a language feature.
That being said, I recently integrated mir's Algebraic and Nullable into
a project. Integration was pretty easy, and the code was clear and easy
to understand. That being said, the terminology of "Some", "None",
"Result" and "Err" in Rust are yet easier to understand.
http://mir-core.libmir.org/mir_algebraic.html
Finally, in addition to `mir.algebraic`, `sumtype`, `Optional`, and
`Result` packages, I would add that Tchaloupka's `expected` package
looks great:
https://code.dlang.org/packages/expected
Re: Performance issue with fiber
On 7/27/21 9:12 PM, Denis Feklushkin wrote: Spawning fiber is expensive (but not so expensive as spawning thread, of course), but switching is fast. Thus, you can spawn and pause "workers" fibers for avaiting of jobs. (Probably, this behaviour is already implemented in number of libraries and it isn't actually need to implement another one.) Agree with sibling comment by hanabi1224: spawning fiber (in other language runtimes) is INCREDIBLY fast, even though they have stack. Something is wrong here.
Re: How to parse JSON in D?
On 3/29/21 1:44 PM, drug wrote: I use asdf https://code.dlang.org/packages/asdf Also vibe-d https://code.dlang.org/packages/vibe-d has vibe-d:data subpackage Also a happy `asdf` user
Re: noobie question, dub or meson?
On 3/19/21 4:04 AM, Chris Piker wrote: Has there ever been talk of adding C source code support to dub, or is that a forbidden topic? I know if dub supported C, all my C libs and all my necessary dependencies (openssl, expat, etc.) would have dub.json files before the weekend was over. Chris: for one of my (D) libraries that also links in an .o file that's built from C source, I have a makefile for the C and call `make` during the dub build process. It is not incredibly sophisticated, but works well for us. Here is the dubfile with `preBuildCommands`: https://github.com/blachlylab/intervaltree/blob/master/dub.json Kind regards
Re: Introspection of exceptions that a function can throw
On 2/24/21 2:38 PM, Mark wrote:
Is there a way to obtain a list, at compile-time, of all the exception
types that a function might throw (directly or through a call to another
function)?
Thanks.
Crazy idea:
Could a program import its own source file as a string (`string source =
import('thisfile.d')`) and `-J` , then use a lexer/parser to
generate AST of the source code and extract exceptions potentially
thrown by given functions -- all at compile time?
Re: Profiling
On 2/9/21 12:45 AM, JG wrote: I was trying to profile a d program. So I ran: dub build --build=profile. I then ran the program and it produced trace.log and trace.def. I then ran d-profile-viewer and got the following error: std.conv.ConvException@/home/jg/dlang/ldc-1.24.0/bin/../import/std/conv.d(2382): Unexpected '-' when converting from type char[] to type ulong ??:? [0x564a8630fda5] ??:? [0x564a86333286] ??:? [0x564a863199fd] /home/jg/dlang/ldc-1.24.0/bin/../import/std/conv.d:2382 [0x564a862c89a1] /home/jg/dlang/ldc-1.24.0/bin/../import/std/conv.d:1941 [0x564a862c86cc] /home/jg/dlang/ldc-1.24.0/bin/../import/std/conv.d:223 [0x564a862c869c] app.d:1095 [0x564a862cdd71] app.d:1138 [0x564a862ce7ba] ??:? [0x564a863196cb] ??:? [0x564a863195c7] ??:? [0x564a8631941d] /home/jg/dlang/ldc-1.24.0/bin/../import/core/internal/entrypoint.d:42 [0x564a862ce7e4] ??:? __libc_start_main [0x7fd482807cb1] Is d-profile-viewer no longer working? Or did I do something wrong? Speaking of D profile viewer [1] we had good luck with it after fixing the missing timestamps in the profile (I think on Linux platforms it cannot actually measure times and so we had to rewrite the profile file to generate some fake timestamp(s) or timings -- hazy on details). Anyway, if you can get it working it was a nice callgraph tool [1] https://bitbucket.org/andrewtrotman/d-profile-viewer/src/master/
Re: How can I create a Standalone Bundle Portable file application using Dlang?
On 1/20/21 6:50 AM, Marcone wrote: On Tuesday, 19 January 2021 at 14:20:06 UTC, Imperatorn wrote: On Tuesday, 19 January 2021 at 11:10:25 UTC, Marcone wrote: On Tuesday, 19 January 2021 at 06:25:31 UTC, Imperatorn wrote: On Monday, 18 January 2021 at 19:42:22 UTC, Marcone wrote: How can I create a Standalone Bundle Portable file application using Dlang? Could you describe what you mean with "Bundle portable file application"? All dependencies inside an exe file. Like Python Pyinstaller. Do you with "dependencies" mean "resources"? In that case, yeah import is an option someone mentioned. I do not mean resources .res, except if is possible use files inside resources without copy to hard disc and make accessible as it is in local path. I am afraid we are not speaking the same language. Because it sounds like you may not be using "dependencies" as it is conventionally understood in most programming communities, you'll need to give examples. For the record, dependencies are typically either compile-time dependencies or run-time dependencies, and in both cases I think the commonest example would be a library.
Re: Why many programmers don't like GC?
On 1/15/21 4:55 PM, Ola Fosheim Grøstad wrote: On Friday, 15 January 2021 at 21:18:55 UTC, aberba wrote: TL;DR: In summation, the garbage collection system is a robust part of Unreal Engine that affords C++ programmers a lot of safety from memory leaks, as well as convenience. With this high-level discussion, I was aiming to introduce the system at a conceptual level, and I hope I have achieved that. What is your conceptual level? You haven't described what it does, and does not do. But yes, frameworks need that allow "scripting" in some shape or form (compiled or not) has to hide internal structures and intricacies and provide some convenience. Those were not aberba's words, but the author of the first link, in which one does find a conceptual, high level description of GC.
Re: Are there an equivalent to C#'s List in D's stdlib?
On 1/7/21 9:53 PM, Jack wrote:
I coduln't find an equivalent in the documentation, I could see
appender, Array, container etc but none of has a Remove(T item) method
like C#'s [1]. Are there not such implementation and I do have to write
one myself or I just couldn't find?
[1]:
https://docs.microsoft.com/en-us/dotnet/api/system.collections.generic.list-1.remove?view=net-5.0
Speaking for me personally, I would try to work with Ranges[0], and in a
functional style simply filter [1] out in the same way one calls
`Remove` in C#.
for example:
```D-ish
auto someRangeType = functionThatDoesWhatever();
auto rangeWithItemRemoved = someRangeType.filter(x => x.prop != whatever);
```
In the C# docs, Remove is called on a class which has overloaded
`Equals` such that the call to `Remove(new Part(){PartId=1534,
PartName="cogs"});` considers only the PartId and does not match on name.
Again, you could `filter(x => x.PartId != 1534)`, or you could, as in
C#, overload the comparison operator for the class/struct you are
comparing, then `filter(x => x != new Part(1534, "cogs"))`
Finally, although you asked about the standard library, there are many
other container libraries, like emsi-containers [2] which do have List
types that implement a `remove` function just as in C#
[0] http://ddili.org/ders/d.en/ranges.html
[1] https://dlang.org/phobos/std_algorithm_iteration.html#filter
[2] https://dlang-community.github.io/containers/index.html
Re: vibe.d and my first web service
On 11/27/20 12:05 PM, Steven Schveighoffer wrote: FYI, this bug was just fixed (eventcore version 0.9.11). I tested it and it works. Thanks Sönke for fixing this! -Steve https://github.com/vibe-d/vibe-core/issues/205 Hooray and congrats to Soenke and team!
Re: Return values from auto function
On 11/6/20 5:51 AM, Andrey Zherikov wrote:
I have auto function 'f' that might return either an error (with some
text) or a result (with some value). The problem is that the type of the
error is not the same as the type of result so compilation fails.
...
How can I make the original code compilable without templatizing
`failure` function?
Paul Backus has already replied to you so I am surprised he did not plug
is own package "SumType". Maybe it is modesty? This seems like an ideal
time to use this.
All of that being said, I tried to solve this for you using Paul's
SumType package and myself was initially stymied by the fact that the
implicit conversion of a `Success(T)` or `Failure` type did not work
within the ternary op expression*. I rewrote it with if/else which works
great and is only slightly more verbose than with ternary op.
```D
alias Result = SumType!(Success!int, Failure);
auto f(int i)
{
Result retval;
if (i > 0)
retval = Success!int(i);
else
retval = Failure("Sorry!");
return retval;
}
```
the above relies on suitable definition of `Success(T)` and `Failure`
structs, obviously.
* This fails due to different types within the same expression:
```
retval = i > 0 ? Success!int(i) : Failure("Sorry");
```
casting each to `Result` compiles, but is verbose:
```
return i > 0 ? cast(Result) Success!int(i) : cast(Result)
Failure("Sorry");
```
** Could someone more knowledgeable than me explain why implicit
conversion does not happen with the ternary op, but works fine with
if/else? Presumably, it is because the op returns a single type and
implicit conversion is performed after computing the expression's return
type? If this somehow worked, it would make the SumType package much
more ergonomic **
Re: Dub cmdline overrides?
On 11/7/20 7:58 AM, Arjan wrote: Is there a cmdline switch to DUB to override certain dub.sdl settings for a dependency? Like the addition or override to lib dirs or link-libs? For example once and a while I run into linking issues with symbols not found due to the `soname` being different on my system than specified in some dependency dub.sdl. Or the lib path to the shared lib is different. I don't think so, as I have also looked for that very feature in the past. Probably it is not supported in order to make builds more deterministic the dubfile is a record of how the binary was built (kind of, since there are obviously multiple configurations...)
Re: How to use bootstrap with vibe.d.
On Thursday, 5 November 2020 at 16:22:11 UTC, Alaindevos wrote: This is from the bootstrap documentation. I think you must adapt this to .dt files. Correct. It looks like flask_bootstrap is just a convenience that injects the js and css scripts or script URI for you into master flask template.
Re: How to use bootstrap with vibe.d.
On Wednesday, 4 November 2020 at 19:01:16 UTC, Alaindevos wrote: (title). In flask it is "from flask_bootstrap import Bootstrap". But what do you have to do with vibe.d ? I am not sure you really understand what bootstrap is?
Re: Why is vibe.d json serializer/deserializer so complex?
On 10/31/20 8:28 PM, Jesse Phillips wrote: Well I was putting this together, but didn't want to attempt submission until I felt I would be able to put in the time for the review process https://github.com/JesseKPhillips/DIPs/blob/serialize/attribute/DIPs/1NNN-jkp.md Bravo! An idea whose time has come. I will follow this with interest. May take some horse-trading, I imagine.
Re: Why is vibe.d json serializer/deserializer so complex?
On 10/30/20 1:56 PM, Steven Schveighoffer wrote: I was looking to report an enhancement request to vibe.data.json (filed here: https://github.com/vibe-d/vibe.d/issues/2490), and I started looking at the serialization code for vibe. It's really really complicated, and I'm just wondering if this is a case of overengineering, or if there's a logic behind making this so complicated. My iopipejson serializer is super simple comparatively. Is there a benefit to having all the complexity? I know they support both json and bson, but I cannot follow the code very well, and I'm not sure what happens where, and which types are responsible for what. -Steve So I've been meaning to ask this as I have been learning Rust off-and-on recently for web development, and was impressed by the traits functionality. In particular, with traits and some agreed upon API, many packages are interchangeable in terms of various functionalities, including JSON serialization/deserialization. What would be the nearest analog facility in D -- supposing we could agree on a standard API -- to facilitate pluggable serializers? I am a big fan of asdf (and Steve, haven't tried iopipejson yet, but will do). It would be nice to not rewrite code to try a different serializer, and Rust is really neat in this regard.
Re: Is there something I'm not getting here?
On 10/26/20 9:19 PM, Ruby The Roobster wrote:
Following code doesn't work(it's not the actual code but it represents
it). Is there some rule about function overrides that I don't know about?
...
The error I keep getting no matter what says: Error: Multiple Overrides
of Same Function. Anybody know what I should do?
It works for me.
The "shorten" link on run.dlang.io no longer works, but here is a
working example:
```
import std;
class A {
public override string toString() {
return "a";
}
}
class B : A {
public override string toString() {
return "b";
}
}
void main()
{
A a = new A();
B b = new B();
writeln(a);
writeln(b);
}
```
Re: Passing pointer to extern(C++) templated function
On 10/13/20 5:23 AM, Jamie wrote: Building with: g++ -c a.cpp dmd main.d a.o Throws the error: /usr/bin/ld: main.o: in function `_Dmain': main.d:(.text._Dmain[_Dmain]+0x31): undefined reference to `void func3(int*, int*)' /usr/bin/ld: main.d:(.text._Dmain[_Dmain]+0x3e): undefined reference to `void func4(int const*, int const)' collect2: error: ld returned 1 exit status Error: linker exited with status 1 Is the template even instantiated? With just a template definition and an object file I am surprised you even have a symbol?
Re: question on dub and postgresql
On 10/5/20 11:42 AM, Alaindevos wrote: Use "rangify" template to get forward range from answer Thanks, this answers the question on programmatic level. Yet I guess something is special with the answer datatype which makes foreach to fail. Instead of thinking of it as "foreach failing," instead consider that the library author did not implement foreach.
Re: Can opDollar support a jagged 2D array?
On 10/2/20 9:32 AM, Steven Schveighoffer wrote: This seems like an oversight. But it's not impossible. Thank you Steve. Is there any chance that this mechanism will ever be revised? Presumably it would require a DIP. Just curry the information to the receiver. opDollar doesn't have to return a size_t. This is indeed pretty clever; I would not have ever though to have opDollar return a non-integral value. This again suggests the whole thing needs to be revised, but this will work for now -- thanks again!
Can opDollar support a jagged 2D array?
Suppose I have a data structure encoding sequence lengths: seq1: 0 1 2 ... N seq2: 0 1 2 3 4 ... M seq3: 0 1 ... P I would like to write opIndex and opDollar to support the notation obj[seq, x .. $] to retrieve sequences. However, given that opDollar is templated on dimension (always 1 in this example) and has no information calling function's context/dimension 0 parameter, this seems impossible. Am I missing an easy solution? Kind regards
Re: what's the best way to convert a sysTime to local machine's time (zone)?
On 9/24/20 6:22 PM, mw wrote: Hi, I'm just wondering what's the best way to convert sysTime to local machine's time (zone)? Is there any library function does this already? https://dlang.org/phobos/std_datetime_systime.html#SysTime (The time in SysTime is kept internally in hnsecs from midnight, January 1st, 1 A.D. UTC.) Thanks. It is definitely not easy to find. https://dlang.org/phobos/std_datetime_systime.html#.SysTime.timezone SysTime struct contains member fn timezone which will return the current settings' TZ ; you can then apply this TZ to other functions in std.datetime to transform datetimes to the TZ [of your choice].
Re: DDoc generation
On 9/18/20 9:35 AM, Russel Winder wrote: On Fri, 2020-09-18 at 09:02 -0400, Steven Schveighoffer via Digitalmars-d- learn wrote: […] it ddoc files, and compile those along with your application. https://dlang.org/spec/ddoc.html#using_ddoc_for_other_documentation Any small project examples anywhere? I am also learning about ddoc generation (something that IMO could stand to be much better , ahem, documented). A nice example I've found is the libmir site: https://www.libmir.org/ http://mir-algorithm.libmir.org/ (mir-core., mir-random., etc.) and its documentation generation infrastructure: https://github.com/libmir/circle-dlang
Re: Proper way to exit with specific exit code?
On 9/17/20 12:46 PM, IGotD- wrote: The only way is to return from main. The thing is that druntime runs initialization before main and then returning from main it runs all the tear down code including cleaning up the GC. This means there is no equivalent of the exit function in the C library. Calling exit from D means that there will be no cleanup in D environment. ... I never considered this -- so when I call core.stdc.stdlib : exit, none of my destructors get called? Presumably also not scope(exit) blocks? If this is the case, could we simply add a publically-accessible shutdown hook in the runtime?
Re: Why is BOM required to use unicode in tokens?
On 9/15/20 8:24 PM, James Blachly wrote: Again with the self-reply :/ Forgot the reference: https://www.unicode.org/versions/Unicode13.0.0/ch22.pdf
Re: Why is BOM required to use unicode in tokens?
On 9/15/20 8:10 PM, James Blachly wrote: Steve: It sounds as if the spec is correct but the glyph (codepoint?) range is outdated. If this is the case, it would be a worthwhile update. Do you really think it would be rejected out of hand? OK interestingly this code point 0x2202 falls within the range "mathematical operators" [0] , and I could see why in general a range called "operators" (which includes e.g. set membership, relations, operators you would see in abstract algebra, etc.) however, the first 8 codepoints in the range are "Miscellaneous mathematical symbols" and include several that would be appropriately included as/in token names. Indeed, chapter 22, page 823 of the Unicode standard groups ∂ U+2202 (the partial differential symbol in question) along with "Basic Set of Alphanumeric Characters" that includes Latin 0-9, [a-z,A-Z], uppercase greek A-Ω, nabla and variant theta, the lowercase Greek letters, and besides U+2202 ∂, six additional glyph variants. Due to de-duplication of code points, some things that may rightly appear in multiple ranges (like U+2202 ∂) are deduplicated and that I think is the fate that befell this variant delta.
Re: Why is BOM required to use unicode in tokens?
On 9/15/20 10:59 AM, Steven Schveighoffer wrote: Thanks to Paul, Jon, Dominikus and H.S. for thoughtful responses. What will it take (i.e. order of difficulty) to get this fixed -- will merely a bug report (and PR, not sure if I can tackle or not) do it, or will this require more in-depth discussion with compiler maintainers? I'm thinking your issue will not be fixed (just like we don't allow $abc to be an identifier). But the spec can be fixed to refer to the correct standards. -Steve Steve: It sounds as if the spec is correct but the glyph (codepoint?) range is outdated. If this is the case, it would be a worthwhile update. Do you really think it would be rejected out of hand?
Re: Why is BOM required to use unicode in tokens?
On 9/15/20 4:36 AM, Dominikus Dittes Scherkl wrote: On Tuesday, 15 September 2020 at 06:49:08 UTC, Jon Degenhardt wrote: On Tuesday, 15 September 2020 at 02:23:31 UTC, Paul Backus wrote: Identifiers start with a letter, _, or universal alpha, and are followed by any number of letters, _, digits, or universal alphas. Universal alphas are as defined in ISO/IEC 9899:1999(E) Appendix D of the C99 Standard. I was unable to find the definition of a "universal alpha", or whether that includes non-ascii alphabetic characters. ISO/IEC 9899:1999 (E) Annex D Universal character names for identifiers - ... --- This is outdated to the brim. Also it doesn't allow for letter-like symbols (which is debatable, but especially the mathematical ones like double-struck letters are intended for such use). Instead of some old C-Standard, D should better rely directly on the properties from UnicodeData.txt, which is updated with every new unicode version. Thanks to Paul, Jon, Dominikus and H.S. for thoughtful responses. What will it take (i.e. order of difficulty) to get this fixed -- will merely a bug report (and PR, not sure if I can tackle or not) do it, or will this require more in-depth discussion with compiler maintainers? James
Why is BOM required to use unicode in tokens?
I wish to write a function including ∂x and ∂y (these are trivial to type with appropriate keyboard shortcuts - alt+d on Mac), but without a unicode byte order mark at the beginning of the file, the lexer rejects the tokens. It is not apparently easy to insert such marks (AFAICT no common tool does this specifically), while other languages work fine (i.e., accept unicode in their source) without it. Is there a downside to at least presuming UTF-8?
Re: Call C variadic function from D variadic function
On 9/13/20 2:35 PM, ag0aep6g wrote: Easy peasy: import std.meta: Repeat; Repeat!(kvargs.length, const(char)*) zs; foreach (i, ref z; zs) z = toStringz(kvargs[i]); return sam_hdr_add_line(this.h, type.ptr, zs, null); Great, thank you! By the way, `kvargs` is not a dynamic array. Its length is not dynamic, and it's not an array. I was incorrectly recalling the error message compiler emitted when using the typesafe variadic FUNCTION (your method 1, below) Also, you don't just want to pass the parameters forward. That would be trivial: `sam_hdr_add_line(this.h, type.ptr, kvargs, null)`. You want to run them through another function first. That's where the difficulty comes from. Right, I indeed left that out of the problem statement; the trivial variadic template params pass right on through which is awesome. I don't see when it would matter how the function is called, but you can declare it in two different ways: My assumption is that if called passing a [runtime] dynamic array, of course the parameter list cannot be known, but the (below) "Type 1 True typesafe variadic" can also be called with a fixed parameter list known at compile-time. 1) True typesafe variadic: auto addLine(RecordType type, string[] kvargs ...) 2) Template + typesafe variadic: auto addLine(size_t n)(RecordType type, string[n] kvargs ...) In the first one, `kvargs.length` is a dynamic value. You can't use it to generate the arguments for a `sam_hdr_add_line` call. My point of surprise was that -- depending on how invoked ( f(anArray) versus f(1,2,3) the compiler may know at compile-time the parameter list. But from a complexity standpoint it makes sense that it is nonetheless not possible to use. In the second one, `kvargs.length` is a static value. So you can do the same things as in the `T...` template. And just like the `T...` template, it will generate a new function for every distinct `kvargs.length`. Great, I never thought of parameterizing as a static array. This looks the best IMO.
Call C variadic function from D variadic function
Summary:
Can a typesafe D variadic function, or D variadic template pass its
parameters to a C variadic function?
Background:
I maintain a library binding [0] to htslib, a high-performance and very
widely used C library for high-throughput sequencing (hts) data files.
We use this internally and haven't polished it for a release on the
announce forum or biomed twitter, etc. yet.
In the course of upgrading it to support the latest API/ABI (htslib-1.10
/ so.3), I need to add support for several new functions.
One of these is a variadic function with the signature:
`int sam_hdr_add_line(sam_hdr_t *h, const char *type, ...);`
Of course, we can call this directly from D with hardcoded parameters.
However, one of the focuses of our library is "bindings + wrappers" to
make this feel more like native D. Thus, we want a variadic function to
which we may pass D strings (it is also a struct member function).
With help from Herringway on IRC, we came up with a solution using mixin:
```
/// Add a single line to an existing header
auto addLine(T...)(RecordType type, T kvargs)
if(kvargs.length > 0 && isSomeString!(T[0]))
{
static assert (kvargs.length %2 == 0); // K-V pairs => even
number of variadic args
string varargMagic(size_t len)
{
string args = "sam_hdr_add_line(this.h, type.ptr, ";
for(int i=0; iInterestingly, compilation fails if the mixin consists only of the
comma-separated parameters ("Comma expression" [1])
Question:
If a variadic template, despite presenting to the user a "dynamic
array", MUST know its parameter list at compile-time, is there a way
(other than with mixins as shown) to pass this parameter list to
extern(C) linkage function with variadic parameters?
(bonus question: if yes, can it be done with typesafe variadic function
where I believe parameter list is known at either compile time OR
runtime, depending on how called)
Thanks all in advance
[0] dhtslib
https://code.dlang.org/packages/dhtslib
https://github.com/blachlylab/dhtslib
[1] https://dlang.org/spec/expression.html#expression
Re: Vibe-D File Question
On 9/11/20 7:28 AM, Daniel Kozak wrote:
void fun(HTTPServerRequest req, HTTPServerResponse res) nothrow
{
try
{
res.headers["Content-Disposition"] = "filename=\"muj.csv\"";
res.writeBody("some;csv;data", "text/csv");
}
catch (Exception e)
{}
}
Selim, note the Content-Disposition header in particular.
https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Disposition
Re: I think Associative Array should throw Exception
On 9/1/20 2:55 PM, Steven Schveighoffer wrote: On 9/1/20 2:20 PM, Jesse Phillips wrote: Using RangeError is nice as it allows code to use array index inside `nothrow.` This is the big sticking point -- code that is nothrow would no longer be able to use AAs. It makes the idea, unfortunately, a non-starter. ... -Steve Steve, are there not several (probably better, faster) alternatives to the built-in AA that are nothrow? I think a nice way to look at the built-in AA is an easy default for quick scripts, new users, etc., much like the default of `throw` status of a function or code block. Advanced users, (i.e. those using nothrow annotation) could select a more efficient AA implementation anyway.
Re: How do I statically build a project using DUB?
On Saturday, 29 August 2020 at 11:27:28 UTC, Kirill wrote: I need a stand-alone executable that does not require the user to install any libraries on their computer. Everything should be packed into the executable. I understand that I need to statically link all of the libraries I use in my project, but how do I do this? What do I need to add to dub.json file? What compiler flags do I need to use? Thanks in advance. It may be extremely difficult if you intend to also link libc; the gethostbyname DNS functions in glibc do not support static linking. OTOH you can create a fairly portably binary by static linking everything EXCEPT libc (I.e., do not pass -static flag to linker) — here you would need to link to the .a files of all your projects library deps as well as your dependencies dependencies...
Re: Vibe.d timer - change callback?
On Tuesday, 25 August 2020 at 18:42:53 UTC, codic wrote:
I'd like to be able to change the callback of a vibe.d Timer
(eg created with
http://vibe-core.dpldocs.info/v1.9.3/vibe.core.core.createTimer.html) after creation, something like:
auto timer = createTimer();
timer.rearm(duration, /*...*/);
timer.callback = delegate {
// things
}
Would creating a dynamic redirection function as delegate serve
your purpose?
https://dlang.org/library/std/functional/to_delegate.html
You can also pass object having `opCall` to `to_delegate` and th
is could also provide dynamic dispatch.
in; scope; scope ref; DIP1000; documentation
Peeling off from Mathias Lang's thread in General about making 'in' useful, for some novice questions: 1. The thread involves 'in' qualifier. Documentation (https://dlang.org/spec/function.html#param-storage) indicates that `in` is defined as `scope const` and should not be used as it is not implemented. **Is this [fact and recommendation] still true?** 2. Regarding scope: On 8/5/20 3:27 AM, Fynn Schröder wrote: On Friday, 31 July 2020 at 21:49:25 UTC, Mathias LANG wrote: I hope this will generate interest with people hitting the same problem. I've literally yesterday written some new code with `const scope ref` in almost every function to pass large, complex structs. Occasionally, I had to store rvalues temporarily to pass as lvalues (non-templated code). I would rather simply put `in` on those parameters :-) It's a lot easier to grasp function signatures only using `in` and `out` on parameters (and their effect/purpose being immediately obvious to new D programmers!) Is "scope ref" documented somewhere specifically? I found https://dlang.org/spec/function.html#scope-parameters which discusses the use of `scope` with ref type parameters, but the example given is pointer-based. Is it correct that `scope ref T` behaves the same as `scope T*` ? Regarding `scope` more generally, DIP1000 shows as "superseded" -- **can I still rely on this document for guidance?** We have a `-dip1000` flag but a superseded DIP. The discordance is extremely confusing. I am glad D is iterating quickly and improving on safety, but I have found that documentation may not well recent changes in this area. Consequently I am reluctant to use (newer) features related to memory safety. If this is all comprehensively documented somewhere please let me know!
Re: Master Thesis using D Programming language.
On Monday, 24 August 2020 at 19:56:49 UTC, Tariq Siddiqui wrote: Hello everyone, I am looking for a master thesis topic using D Programming language. Earlier I choose Design by Introspection, but I did not find enough material in academic journals. DbI total material which I found is DConf Andrei talk and the similar talk at Google campus, which starts with 50 Deutsche Mark story and ends with explaining PbD, DbI and other Dlang internals. No doubt that Andrei's discussion was great. DbI as a topic is excellent, but as per my university requirements, I was not able to find five articles in the last five years in any academic journal, to start the initial discussion about the research topic. I am still opened with my topic, next week, I have to submit my draft proposal. Till now, I did not meet my dissertation advisor. I am looking for something practical and less theoretical. I have found some thesis done using Rust, you guys as a language expert can these below projects be achievable using D Programming language. http://www.barrelfish.org/publications/ma-foellmic-bfrust.pdf https://www.diva-portal.org/smash/get/diva2:1238890/FULLTEXT01.pdf https://github.com/Gankra/thesis/blob/master/thesis.pdf Regards, Tariq Siddiqui. Well, what would you like to study? Generally, the thesis will be of a topic that is (a) great interest to you and (b) has room for improvement in the field. The theses you listed cover OS development, memory safe kernel programming, and safety generally, respectively. Is this the area you wish to work in? What about other areas, such as concurrency, message passing, high performance, Type Theory, etc.? You mentioned Design by Introspection hard to find material about. What if you broaden this a bit and consider the topic of metaprogramming more generally? Best of luck to you
Re: How to sort a multidimensional ndslice?
On Tuesday, 18 August 2020 at 13:07:56 UTC, Arredondo wrote: On Tuesday, 18 August 2020 at 04:07:56 UTC, 9il wrote: To reorder the columns data according to precomputed index: auto index = a.byDim!1.map!sum.slice; Hello Ilya, thanks for the answer! Unfortunately I can't use it because I don't have (and can't define) a sorting index for my columns. I only have a predicate `larger(c1, c2)` that compares two columns to decide which one is "larger". Cheers! Armando. Armando, I believe you can just pass your predicate to the sort! template http://docs.algorithm.dlang.io/latest/mir_ndslice_sorting.html
Re: vibe.d and my first web service
On 7/18/20 8:16 AM, Andre Pany wrote: On Saturday, 18 July 2020 at 09:10:04 UTC, Mr. Backup wrote: >> ... I started the program with "dub" command and everything worked as I expected. Except that there were a lot "deprecation" warnings and long time to compile.But when I exit the service by ctrl + c and start again the program cannot start again with error message: ... I assume you are using vibe.d 0.8.4 or older. Please check whether adding this to dub.json solves your problem: "versions": [ "VibeHighEventPriority" ] (Restart your pc) Vibe.d 0.9 0 will be released soon. I hope it will work out of the box there. Unfortunately the problem still occurs with Vibe.d 0.9.0 IMO **this is the single most important problem to fix** for vibe.d -- if the most basic of examples (indeed, supplied by dub itself) fails so spectacularly, the casual new user will not spend the time to find out why this is happening, but instead move on. The ctrl-C non-termination bug has existed since at least 2015 from what I can tell from the forums. Tangent: Does Sönke have a Patreon or the project an OpenCollective etc. ? I would be willing to support fixing of some of these bugs. Alternatively, could we vote on whether a web framework is worthy of foundation support? Having an ergonomic, workable web framework is absolutely essential to surviving as a language in 2020 (notable exception being 800# gorilla incumbents C/C++).
Re: generating random numbers
On 8/10/20 1:51 AM, Andy Balba wrote: generating random numbers using https://dlang.org/library/std/random/uniform01.html I find the example given in this section totally incomprehensible .. Can any help me answer two simple questions: How to generate a random floating number in range [0,1) ? How to set a seed value, prior to generating random values ? Tangential: I also find mir-random [0] a very nice library that is easy to use and has no deps on D runtime, so can be used in Das Better C mode. I think it is also a better random engine than phobos [0] https://code.dlang.org/packages/mir-random
Re: Get symbols (and/or UDAs) of subclass from superclass
On 3/15/20 5:28 PM, Simen Kjærås wrote:
...
Since toStringImpl will always call toStringBase, this could perhaps
better be modeled with a template mixin:
mixin template DerivedToString() {
override string toStringImpl() {
return this.toStringBase();
}
}
class Derived2 : Base {
mixin DerivedToString!();
}
This way, you can have all the logic of toString in the base class, and
the only thing a subclass will have to include is one line for the
mixin. In addition, since toStringImpl is abstract, the implementer of a
subclass will get a compile-time error if he or she forgets to do either
the mixin or override toStringImpl themselves.
--
Simen
Thanks to you and Basile for responses and distinct solutions to
consider. I am working on the mixin approach now, but with a brief
mixinline in each derived subclass, I do not even need to call a
superclass method -- just write the display code once with UDA
filtering. I think this is the most sensible approach, until something
else unexpected comes up :)
Get symbols (and/or UDAs) of subclass from superclass
I would like to programmatically retrieve members of a subclass to
create a self-documenting interface. I am afraid that my approach is not
possible due to need for compile time __traits / std.traits, and runtime
typeinfo. My proposed approach is as follows:
class Base
{
string whatever;
string toString()
{
// loop over __traits(allMembers, typeof(this)) or
getSymbolsByUDA, etc.
}
}
/// There may be a dozen Derived classes
class Derived1 : Base
{
@Config("a name", "a description")
float probability;
}
class Derived2 : Base
{
@Config("another", "more description")
int replicates;
}
...
Unfortunately, I am afraid this doesn't look possible because of the
need for compile-time UDAs and runtime TypeInfo. Is there a way to do
this without re-implementing toString in every single derived class? I
expect there to be many derived classes.
Other ideas welcomed, as I usually write C-style D and am only recently
taking a stab at OO Inheritance features.
Thanks in advance.
James
Re: weekly news?
On 1/23/20 8:13 PM, Mike Parker wrote: On Thursday, 23 January 2020 at 15:44:10 UTC, Adam D. Ruppe wrote: Or delete all that wordpress junk and make something in D :P I intend to delete all that Wordpress junk and go completely static eventually. Mike, I know we're not a golang shop, but I highly recommend switching to HUGO for the blog.
Re: weekly news?
On 1/22/20 7:58 PM, Adam D. Ruppe wrote: On Thursday, 23 January 2020 at 00:52:10 UTC, Mike Parker wrote: Got any examples? No one has reported this to me before and I haven’t encountered a 404 in a while. Almost all of them! Hit F12 to open browser tools and notice the network tab: https://dlang.org/blog/2020/01/08/recent-d-compiler-releases/ https://dlang.org/blog/2020/01/04/dconf-2020-double-decker-edition/ and more. The HTML is displayed, but it has the 404 code so according to the http spec you are actually displaying it all as error pages! HOLY NEGATIVE SEO BATMAN curl -v shows that it is returning 404 indeed.
Re: Some comments on learning D using the tour
On 1/15/20 3:06 PM, mark wrote: I am learning D for the first time. While I wait for Mike Parker's "Learning D" book to arrive, I have started using the tour. I really like the tour, especially the fact that you can run and tweak the code as well as read the explanations. However, ... Mark, thank you for your comments. It is always valuable to hear the perspective of someone approaching any problem or situation with a fresh set of eyes.
Re: druntime 2.087 regression? (was: Old codebase stops compiling at 2.087)
On 11/17/19 7:15 PM, Steven Schveighoffer wrote:
On 11/17/19 10:45 AM, James Blachly wrote:
/home/james/dmd2.087/dmd2/linux/bin64/../../src/druntime/import/object.d(3453,36):
Error: cannot implicitly convert expression aa of type
shared(GSeqAllele[string]) to const(shared(GSeqAllele)[string])
There's a subtle removing of the shared from the entire AA. Is that on
purpose?
i.e. I see shared(GSeqAllele[string]) in one, and
shared(GSeqAllele)[string] in another.
-Steve
Steve:
Sorry for the delay in replying. That is the runtime removing the shared
from the entire AA, not our code. I point out the change that induces
this with a link to github.
Should I move this discussion to the main D group? My primary concerns are:
0. Ask if it is intended behavior that the runtime cannot handle a
shared AA post 2.086.1?
1. Report this as bug
2. Ask why this commit ("object: Declare private struct AA and fix aaA
function signatures ") not mentioned in the changelog for 2.087?
Thanks in advance
druntime 2.087 regression? (was: Old codebase stops compiling at 2.087)
TL;DR druntime regression?
https://gist.github.com/jblachly/78c5762bbfea65b09e7a1417ad763019
---
Our team has an older codebase that compiled fine up until frontend
version 2.087 (builds with 2.086.1). Now, compiler (DMD2 and LDC2)
complains about implicit conversion of shared(AA) to const(shared(AA)).
The codebase is private (could possibly make it public soon) but the
error involves an AA inside a shared struct.
```
/home/james/dmd2.087/dmd2/linux/bin64/../../src/druntime/import/object.d(3453,36):
Error: cannot implicitly convert expression aa of type
shared(GSeqAllele[string]) to const(shared(GSeqAllele)[string])
source/polytyper/gseq.d(231,33): Error: template instance
`object.values!(shared(GSeqAllele[string]), shared(GSeqAllele), string)`
error instantiating
/home/james/dmd2.087/dmd2/linux/bin64/../../src/druntime/import/object.d(3402,36):
Error: cannot implicitly convert expression aa of type
shared(GSeqAllele[string]) to const(shared(GSeqAllele)[string])
source/polytyper/gseq.d(280,35): Error: template instance
`object.keys!(shared(GSeqAllele[string]), shared(GSeqAllele), string)`
error instantiating
```
(line breaks added for clarity)
The two triggering lines both iterate over a built-in AA
gseq.d:231:foreach (a; this.alleles.values)
gseq.d:208:foreach (key; this.alleles.keys)
Looking at the changelog for 2.087 (
https://dlang.org/changelog/2.087.0.html ) I do not see any obvious
culprits. git blame suggests this is the responsible commit:
https://github.com/dlang/druntime/commit/af86e7db58f4b792e45bdc3ee43c17aadc9d54ab#diff-a68e58fcf0de5aa198fcaceafe4e8cf9L3430-R3454
From this change, it looks like the runtime now cannot handle a shared
AA -- is this right? A minimal reproducible example is here:
https://gist.github.com/jblachly/78c5762bbfea65b09e7a1417ad763019
Thanks in advance for help
James
PS: Why is this commit ("object: Declare private struct AA and fix aaA
function signatures ") not mentioned in the changelog?
Re: How to Unqual an array?
On 11/16/19 10:20 AM, James Blachly wrote: On 11/16/19 9:48 AM, James Blachly wrote: I am trying to write templated code that will take a character array -- mutable, const, or immutable (string). I am aware of isSomeString, but I am still curious about Unqual array from a learning perspective. Thank you both Steve and Anonymouse! Regarding Steve's comment -- this should be made clear in documentation no? Regarding Anonymouse's code snippet, I've definitely saved that for future. thank you. James
Re: How to Unqual an array?
On 11/16/19 9:48 AM, James Blachly wrote: I am trying to write templated code that will take a character array -- mutable, const, or immutable (string). I am aware of isSomeString, but I am still curious about Unqual array from a learning perspective.
How to Unqual an array?
I am trying to write templated code that will take a character array -- mutable, const, or immutable (string). static assert(is(Unqual!(const char) == char)); (Succeeds) static assert(is(Unqual!(const(char)[]) == char[])); Error: static assert: `is(const(char)[] == char[])` is false Is the template trying to strip the qualifier from the [] rather than the char?
Re: Why is sformat and formattedWrite (appender) allocating GC mem here?
On 8/31/19 5:12 PM, ag0aep6g wrote: I've made a pull request to get rid of those allocations: https://github.com/dlang/phobos/pull/7163 Wonderful! For my own learning, why was a unittest to ensure no GC added to sformat instead of a @nogc annotation?
Do I understand std.experimental.allocator composition correctly?
The documentation for std.experimental.allocator is a little dense and I wanted to make sure I am understanding composition correctly. Suppose I have the following, taken more-or-less direct from the docs: auto batchAllocator = AllocatorList!( (size_t n) => Region!Mallocator(max(n, 1024*1024)) )(); https://dlang.org/phobos/std_experimental_allocator_building_blocks_region.html#.Region Is my understanding correct that Mallocator, the ParentAllocator in Region's construction will allocate a block of at least 1 MiB when a request comes in, but calls to batchAllocator.make!(T) will allocate only enough (rounded up to some ideal like a power of 2) to store T -- until it runs out, then the AllocatorList will allocate another block of 1 MiB, and so on? Essentially, I need to allocate memory for objects in an inner loop, and I thought a better strategy would be to make big block alloc(s) as a pool and then hand out internal pointers into the pool. I previously did this will malloc() and std.conv.emplace, but this looks like a better solution, if my understanding is correct. Thank you!
Re: How to get name of my application (project)
On 8/3/19 5:26 AM, Andrey wrote: Hello, how to get name of my application (project) that we write in dub.json? Is there any compile-time constant like __MODULE__? Dear Andrey: Perhaps this is similar to what you are looking for: https://dlang.org/spec/grammar.html#SpecialKeyword SpecialKeyword: __FILE__ __FILE_FULL_PATH__ __MODULE__ __LINE__ __FUNCTION__ __PRETTY_FUNCTION__ These are available at compile time. Kind regards.
Re: Basic Linear Algebra and D's Array Operation
On 5/19/19 2:34 AM, Andrew Edwards wrote: P.S. Why do we still have two sets of documentations ([1],[2]) for the language? Which is the official one and when can we get rid of the other? [1] https://dlang.org/library/std/array.html [2] https://dlang.org/phobos/std_array.html I have wondered this myself -- anyone?
Re: dub preBuildCommand removed?
On 5/4/19 5:27 PM, Andre Pany wrote: On Saturday, 4 May 2019 at 21:16:25 UTC, James Blachly wrote: It is listed in the build settings table of the referenced link. Kind regards Andre Somehow firefox enabled "whole word" search *rolleyes*, which I did not even realize was a thing. Thanks and sorry for the traffic.
dub preBuildCommand removed?
the preBuildCommand is no longer listed in the dub format spec[1] although it shows up in the google cache for the page. When was it removed, and why? I can't find any announcement. [1] https://dub.pm/package-format-json.html
Re: Cast ptr/len to D-style array
On 5/3/19 5:42 AM, Ali Çehreli wrote: On 05/02/2019 08:21 PM, James Blachly wrote: On 5/2/19 4:05 PM, ag0aep6g wrote: Just slice the pointer with the length: int* ptr; size_t len; int[] arr = ptr[0 .. len]; Perfect thanks. I searched but without using the magic word "slice" I couldn't find meaningful results. Thanks again. Looks like I indexed it under "slice from pointer": http://ddili.org/ders/d.en/pointers.html#ix_pointers.slice%20from%20pointer Ali Thanks Ali, also helpful examples!
Re: Cast ptr/len to D-style array
On 5/2/19 4:05 PM, ag0aep6g wrote: Just slice the pointer with the length: int* ptr; size_t len; int[] arr = ptr[0 .. len]; Perfect thanks. I searched but without using the magic word "slice" I couldn't find meaningful results. Thanks again.
Cast ptr/len to D-style array
I work a lot with C functions, many of which yield pointer + length. Is there a way to cast this or materialize a D-style array backed by the already allocated data (with length) to avoid copies which slow things down? I recognize memory management is a complication. Typically, I would be responsible for free'ing the array later. Thanks in advance
Re: Easiest way to use Linux system C files / tiny C libraries
On 3/29/19 7:52 PM, H. S. Teoh wrote: On Fri, Mar 29, 2019 at 10:48:47PM +, Chris Katko via Digitalmars-d-learn wrote: ...> There are probably other similar gotchas, but these are the ones off the top of my head. Feel free to ask if you're having trouble correctly translating something from C. If all else fails, run the header through a C processor and inspect the output to find out what the *real* definition of something is, if the original C source is so obfuscated you can't easily tell otherwise. Sorry I'm late to the party but another one that we have come across quite a bit is in function signatures: C: const char *stringparam D: const(char)* stringparam Best wishes
Re: Member is @disable this(this), parent uncopyable
On 3/22/19 9:24 AM, Alex wrote: On Friday, 22 March 2019 at 12:08:39 UTC, James Blachly wrote: First, how do we deal with toString, std.format, writeln, etc. with un-copyable objects, when it is only a member that is uncopyable? In my case I got around this by creating a pointer and moving the initialization to the constructor, but I wonder if there are other ways? You could (and should) define your custom toString() method inside the struct S, where un-copyable (or other strange kinds) members are part of. In such a way, you could S s; s.toString(), without any harm, possibly omitting the members, which you are sure of (such as UnrolledList?). Hi Alex, Thanks for replying. I attribute the lack of sensibleness in my post to lack of sleep. I actually am defining toString as member function of S, but it only now occurred to me that structs are always passed by value, not by reference. Of course then it cannot be copied. Thanks again =)
Member is @disable this(this), parent uncopyable
I have a struct S with member containers.UnrolledList [1]. UnrolledList is @disable this(this), but this unfortunately makes my struct S also un-copyable, which now breaks some of my debugging statements which rely on toString, as writeln, format, etc. all copy the object. This leaves me in the unfortunate situation that my release builds work, but debug builds do not. First, how do we deal with toString, std.format, writeln, etc. with un-copyable objects, when it is only a member that is uncopyable? In my case I got around this by creating a pointer and moving the initialization to the constructor, but I wonder if there are other ways? Second, why must an object in its entirety be copy-able for these functions to call toString() ? Finally, the error message gave no clue that it was a member (UnrolledList in my case) that was @disable 'd and it took some digging back through several commits to figure out what was happening -- how could we improve the error messaging? Thanks as always in advance [1] https://github.com/dlang-community/containers
Re: Where is GDC being developed?
On 3/21/19 6:51 PM, James Blachly wrote: On 3/21/19 6:01 AM, Johannes Pfau wrote: On Thursday, 21 March 2019 at 08:19:56 UTC, Per Nordlöw wrote: At https://github.com/D-Programming-GDC/GDC/commits/master there's the heading "This repository has been archived by the owner. It is now read-only." Where will the development of GDC continue? We use https://github.com/D-Programming-GDC/gcc for CI, but commits will go to the GCC SVN first, so GCC SVN or snapshot tarballs is the recommended way to get the latest GDC. There is one exception: When GCC development is in feature freeze, we might provide newer DMD frontends in a gdc-next branch at https://github.com/D-Programming-GDC/gcc . However, so far we have not set up this branch, this will probably happen in the next two weeks. Maybe I'll also provide DDMD-FE backports for GCC9 in that repo, but I'm not sure yet. The latest DDMD-FE is somewhere in the archived repos, but it hasn't been updated for some time. Thanks -- I also tried to figure out how to install GDC just yesterday and gave up. All wiki links and google top results seemed dead ends. A little bit of further information: the downloads listed on https://gdcproject.org/downloads are 2016 versions.
Re: Where is GDC being developed?
On 3/21/19 6:01 AM, Johannes Pfau wrote: On Thursday, 21 March 2019 at 08:19:56 UTC, Per Nordlöw wrote: At https://github.com/D-Programming-GDC/GDC/commits/master there's the heading "This repository has been archived by the owner. It is now read-only." Where will the development of GDC continue? We use https://github.com/D-Programming-GDC/gcc for CI, but commits will go to the GCC SVN first, so GCC SVN or snapshot tarballs is the recommended way to get the latest GDC. There is one exception: When GCC development is in feature freeze, we might provide newer DMD frontends in a gdc-next branch at https://github.com/D-Programming-GDC/gcc . However, so far we have not set up this branch, this will probably happen in the next two weeks. Maybe I'll also provide DDMD-FE backports for GCC9 in that repo, but I'm not sure yet. The latest DDMD-FE is somewhere in the archived repos, but it hasn't been updated for some time. Thanks -- I also tried to figure out how to install GDC just yesterday and gave up. All wiki links and google top results seemed dead ends.
Re: How can I make a nested array and flatten it at run time in D?
On 3/7/19 8:00 PM, Philos Kim wrote: I want to make a nested array and flatten it at run-time like this. auto nestedArray = [1, 2, [3, 4], 5]; auto flattenedArray = myFun(nestedArray); writeln(flattenedArray); // => [1, 2, 3, 4, 5] How can I do this in D? Please help me out! There are simpler ways, but looking at the below Rosetta Code link can be very instructive: https://rosettacode.org/wiki/Flatten_a_list
Re: DMD2 vs LDC2 inliner
On 2/25/19 2:09 AM, Nicholas Wilson wrote:
Leaving aside the issue of why DMD can't handle this, the entire reason
pragma(inline, bool) takes a bool is for it to be (potentially)
predicated.
In this case you want:
version(DigitalMars)
private enum inline_overlaps = false;
else // assuming GDC is good
private enum inline_overlaps = true;
pragma(inline, inline_overlaps)
bool overlaps(IntervalType1, IntervalType2)(IntervalType1 int1,
IntervalType2 int2)
{
return ...;
}
Sadly, the pragma does not accept enum:
Error: pragma `inline` pragma(inline, true or false) expected, not
inline_overlaps
Re: DMD2 vs LDC2 inliner
On 2/25/19 2:09 AM, Nicholas Wilson wrote:
Leaving aside the issue of why DMD can't handle this, the entire reason
pragma(inline, bool) takes a bool is for it to be (potentially) predicated.
In this case you want:
version(DigitalMars)
private enum inline_overlaps = false;
else // assuming GDC is good
private enum inline_overlaps = true;
pragma(inline, inline_overlaps)
bool overlaps(IntervalType1, IntervalType2)(IntervalType1 int1,
IntervalType2 int2)
{
return ...;
}
I still have yet to internalize the power of compile-time values. Thanks
for the reminder and solution!
DMD2 vs LDC2 inliner
Any ideas why DMD2 cannot inline this, but LDC2 has no problem doing so
-- or suggestions for what I can do to make DMD2 inline it?
Alternatively, I could version(DigitalMars) and version(LDC), but AFAICT
this requires me to duplicate the entire template, because I cannot
figure out how to make the version() directive apply only to the pragma.
Template instantiation is with a simple struct having integer members
start and end.
Thanks in advance for tips.
---
pragma(inline, true)
bool overlaps(IntervalType1, IntervalType2)(IntervalType1 int1,
IntervalType2 int2)
if (__traits(hasMember, IntervalType1, "start") &&
__traits(hasMember, IntervalType1, "end") &&
__traits(hasMember, IntervalType2, "start") &&
__traits(hasMember, IntervalType2, "end"))
{
// int1 ====
// int2 === ===
if (int2.start <= int1.start && int1.start < int2.end) return true;
// int1 === ===
// int2 === ===
else if (int1.start <= int2.start && int2.start < int1.end) return
true;
// int1 =| =
// int2 = | =
else return false;
}
Re: std.container.rbtree as Interval Tree?
On Tuesday, 5 February 2019 at 16:24:03 UTC, Eduard Staniloiu
wrote:
I think you are making a slight confusion. Your `Interval`
struct and the `Elem` type that `lowerBound` takes, are the
same type.
You can define your RBTree and Interval as follows
```
struct Interval
{
int start;
int end;
}
alias IntervalTree = RedBlackTree!(Interval, (i1, i2) =>
i1.start < i2.start);
```
Please see this runable example: https://run.dlang.io/is/4cPTik
The in-order traversal will be the same as the wikipedia
example here: https://en.wikipedia.org/wiki/Interval_tree
Hope this helps.
Cheers,
Edi
Edi, thanks for your quick reply!
I do understand that Elem is aliased to my Interval type.
Your suggested rewrite of the less fn is precisely what I was
groaning about (although not explicitly) in terms of rewriting
opCmp to be a simple `this.start < other.start`. The reason that
this is undesirable is that distinct intervals with same starting
coordinates are then considered equal and not added, unless
RBTree tepmlate is instantiated with allowDuplicates. However,
even when allowing (pseudo)duplicates, this means the distinct
intervals with same start but different end coordinates are not
deterministically placed/sorted within the tree, because they are
not sortable with the simple `this.start < other.start` less
function.
Anyway, in the end, I will assume that in my problem domain there
are no degenerate intervals with same start coordinate and use
the simpler less to accomplish goal.
Hopefully the upperBound and lowerBound functions are lazy...
Re: std.container.rbtree as Interval Tree?
On Tuesday, 5 February 2019 at 10:10:44 UTC, RazvanN wrote:
On Monday, 4 February 2019 at 22:54:01 UTC, James Blachly wrote:
I tried to implement an interval tree backed by
std.container.rbtree today and fell flat.
[...]
You can use alias this [1] in your interval element type:
struct IntervalElem
{
size_t start, end;
/* ... other declarations */
alias start this;
}
[1] https://dlang.org/spec/class.html#AliasThis
Thanks -- I always seem to forget about `alias this` !
However, I don't think that this helps me to call functions
expecting type Elem with an integer. At least, it failed in my
test -- could this be because Elem itself is already an alias?
Q2: Would replacing "Elem" with a generic type "T" in the
function signatures for upperBound, lowerBound, and various
related fns like _firstGreater / _firstGreaterEqual solve this
problem?
[...]
Elem is already a generic type. I don't know how you can make
it more generic without adding other template parameters to the
class declaration (which means reimplementing RBTree from
std.container);
Agree, (although I think I would only need to revise only perhaps
25% of the module in this case) but I definitely wanted to avoid
this if possible.
std.container.rbtree as Interval Tree?
I tried to implement an interval tree backed by
std.container.rbtree today and fell flat.
A standard way to make an interval tree is to make an augmented
tree; I supposed since rbtree was a generic container and because
I could define opCmp, this should be a cinch. I ran into two
problems.
First (minor problem), RedBlackTree considers a return value of 0
from opCmp equivalent to "equals", which is discordant with the
guidance given for opCmp.[1] This is a minor pedantic point,
since you cannot store un-orderable elements in the tree anyway.
More importantly, though, I cannot figure out how to implement an
interval query function on the tree. Typically, the tree would
have a "key" that is the left position of the interval and the
augmented part of the tree would be that a second value -- a
right, or end, position. My Elem == key type is a struct
encapsulating both of these (start, end; plus some metadata).
For my Interval element type, I overloaded opCmp to take an
integer, but unfortunately RedBlackTree's upperBound() and
lowerBound() functions are defined in terms of "Elem" which is
aliased to the contained element type, rather than a generic type.
Q1: Is there a simple or elegant way to do this without
re-implementing RedBlackTree? I apologize if it is obvious and I
am missing it. I suppose it may work if I rewrite Interval's
opCmp to not consider the upper bound, and by creating a dummy
interval to pass to upperBound and lowerBound, but that seems
inelegant compared to passing an integer.
Q2: Would replacing "Elem" with a generic type "T" in the
function signatures for upperBound, lowerBound, and various
related fns like _firstGreater / _firstGreaterEqual solve this
problem?
James
[1] https://dlang.org/spec/operatoroverloading.html#eqcmp ("For
example ... x and y are disjoint sets, then neither x < y nor y <
x holds, but that does not imply that x == y. Thus, it is
insufficient to determine equality purely based on opCmp alone. ")
Re: Shared, ref, arrays, and reserve template instantiation
Great -- Thank you both. I previously found Unqual, but it looks like that needs template support so wasn't feasible, hence my question. Neia is right that I tried to cast as in the second case ( but without UFCS -- reserve( cast(int[]), N); ). As an aside, what is going on behind the scenes with the compiler when casting away a property? I did not think cast operations copied data, so was surprised that a cast value is not an lvalue. Regarding Jonathan's comments, we had definitely protected the ~= operations with Mutex, but realized we were doing lots of array appends in a hot loop, and since we have an idea of cardinality ahead of time just wanted to preallocate. Since it is all initialization before concurrent code enters the picture, we'll do what you've suggested and set it up as TL and then cast to shared. James
Shared, ref, arrays, and reserve template instantiation
When I add the "shared" attribute to an array, I am no longer able to call reserve because the template won't instantiate: Error: template object.reserve cannot deduce function from argument types !()(shared(int[]), int), candidates are: /dlang/dmd/linux/bin64/../../src/druntime/import/object.d(4091): object.reserve(T)(ref T[] arr, size_t newcapacity) 1. Shared modifies the type, so the template does not match. Even casting does not seem to work however. Is there something about shared that makes it unable to be taken by reference? 2. Is there a workaround for me to be able to preallocate the array? Kind regards
Re: extern __gshared const(char)* symbol fails
On Friday, 31 August 2018 at 17:50:17 UTC, Steven Schveighoffer
wrote:
What the C compiler is doing is storing it as data, and then
storing the symbol to point at the first element in the data.
When you use const char* in D, it's expecting a *pointer* to be
stored at that address, not the data itself. So using it means
segfault. The static array is the correct translation, even
though it leaks implementation details.
In C, it's working because C has the notion of a symbol being
where an array starts. D has no concept of a C array like that,
every array must have a length. So there is no equivalent you
can use in D -- you have to supply the length.
NKML also wrote:
You need to declare your extern array as array in D and also in
C, so that the compiler would know what that is (an array, not
a pointer). In many situations C compiler would silently
convert an array into a pointer (when it already knows its
dealing with array), but it won't convert a pointer into an
array.
Thank you Steve and NKML for your very clear and concise answers.
This makes perfect sense.
I would like not to write as a static array in D because I cannot
guarantee future version of the library to which I am linking
would not change the length of the data. Steve's trick, below,
looks like the ticket.
Alternatively, you can treat it as a const char:
extern(C) extern const(char) seq_nt16_str;
void main()
{
import core.stdc.stdio;
printf("%s\n", _nt16_str); // should print the string
}
You could wrap it like this:
pragma(mangle, "seq_nt16_str");
private extern(C) extern const(char) _seq_nt16_str_STORAGE;
@property const(char)* seq_nt16_str()
{
return &_seq_nt16_str_STORAGE;
}
To make the code look similar.
-Steve
That is a great trick, and I will use it.
Re: extern __gshared const(char)* symbol fails
On Friday, 31 August 2018 at 17:18:58 UTC, Neia Neutuladh wrote: On Friday, 31 August 2018 at 06:20:09 UTC, James Blachly wrote: Hi all, ... When linking to this library from D, I have declared it as: extern __gshared const(char)* seq_nt16_str; ***But this segfaults when I treat it like an array (e.g. by accessing members by index).*** I believe this should be extern extern(C)? I'm surprised that this segfaults rather than having a link error. A bare `extern` means "this symbol is defined somewhere else". `extern(C)` means "this symbol should have C linkage". I am so sorry -- I should have been more clear that this is in the context of a large header-to-D translation .d file, so the whole thing is wrapped in extern(C) via an extern(C): at the top of the file.
Re: Is there any reason to use non-ref foreach?
On Friday, 31 August 2018 at 12:52:17 UTC, bauss wrote: So basically ... Instead of copying the value, you're just copying the address. I can't see the benefit other than added complexity. I assume a benefit could be observed if you are copying a large struct instead of an int.
extern __gshared const(char)* symbol fails
Hi all, I am linking to a C library which defines a symbol, const char seq_nt16_str[] = "=ACMGRSVTWYHKDBN"; In the C sources, this is an array of 16 bytes (17 I guess, because it is written as a string). In the C headers, it is listed as extern const char seq_nt16_str[]; When linking to this library from another C program, I am able to treat seq_nt16_str as any other array, and being defined as [] fundamentally it is a pointer. When linking to this library from D, I have declared it as: extern __gshared const(char)* seq_nt16_str; ***But this segfaults when I treat it like an array (e.g. by accessing members by index).*** Because I know the length, I can instead declare: extern __gshared const(char)[16] seq_nt16_str; My question is: Why can I not treat it opaquely and use it declared as char* ? Does this have anything to do with it being a global stored in the static data segment?
Re: InputRange help: (1) repeated dtor calls and (2) managing resources needing free()
On Monday, 13 August 2018 at 13:20:25 UTC, Seb wrote: BTW it's very uncommon for empty to do work, it's much more common to do such lazy initialization in `.front`. Thanks Seb, that entire reply is a huge help. By lazy initialization in `.front`, do you mean that I should find a way for `front` to preload the first record? If so, could you help me understand what you mean by lazy init with `front`? `empty` is called before `front` upon first iteration through the Range, so really the init has to be done in the constructor, yes?
Re: InputRange help: (1) repeated dtor calls and (2) managing resources needing free()
On Thursday, 14 June 2018 at 00:42:25 UTC, James Blachly wrote: ... I assume the (apparent) lack of parity between ctor and dtor is because the "default postblit" (which I figured out for a struct means an empty `this(this)` ctor) is called when a copy is made. My understanding is that I cannot disable the default postblit and still act as a range, correct? Should I be overloading this? 2. Directly related to the above, I need, when the range is consumed, to free() the underlying library's iterator handle. Naively, I had the destructor do this, but obviously with multiple calls to ~this I end up with an error free()'ing a pointer that is no longer alloc'd. What is the correct way to handle this situation in D? Other Range and destructor advice generally (e.g., "You should totally change your design or approach to X instead") is always welcomed. James I think I have a handle on #1 (copy of the range is made for consumption which is why dtor is called more often than ctor), but would still be interested in advice regarding #2 (as well as general Range and dtor advice). Here: https://github.com/blachlylab/dhtslib/blob/master/source/dhtslib/tabix.d#L98 I need to free the library's iterator, but the Range's destructor is the wrong place to do this, otherwise memory is freed more than once. Is it a better approach to (a) somehow guard the call to tbx_itr_destroy or (b) create a postblit that creates a new iterator and pointer? (or (c), None of the above) As above, my understanding is that disabling the default posblit prohibits acting as a Range. Thanks in advance
InputRange help: (1) repeated dtor calls and (2) managing resources needing free()
Hi all,
I now really appreciate the power Ranges provide and am an avid
consumer, but am only slowly becoming accustomed to implementing
my own.
In the present problem, I am writing a binding to a C library
(htslib) that provides many functions related to high-throughput
sequencing files. One of these functions is for rapid indexed
lookup into multi-GB files. The library provides a handle to an
iterator which must be supplied to a "get next matching row" type
function, which overall seems perfect for implementation as a
range. You can see my naive implementation here:
https://github.com/blachlylab/dhtslib/blob/master/source/dhtslib/tabix.d
Note that TabixIndexedFile::region returns an InputRange; in the
original implementation, this Range preloaded the first record
(the ctor called popFirst()), but ultimately I realized this was
not workable because copies of the object would always be
non-empty. In some ways, this problem is generalizable to all
InputRanges that represent a file or record stream.
My problems now are at least twofold.
1. If I use the range, the destructor seems to be called many,
many times. This is directly related to problem 2, below, but I
would be interested to understand why this is happening
generally. For example, see:
https://github.com/blachlylab/dhtslib/blob/master/test/tabix_gffreader.d
Here, when I create the range but do not consume it, the ctor and
dtor are called once each, as expected. However, if I
foreach(line; r) { } the destructor is called twice. If I reason
through this, it is because use of the range created a copy to
consume. (?) However, if instead, I writeln( r ), the destructor
is called *five* times. I cannot understand the reason for this,
unless it is black magic required by writeln().
I assume the (apparent) lack of parity between ctor and dtor is
because the "default postblit" (which I figured out for a struct
means an empty `this(this)` ctor) is called when a copy is made.
My understanding is that I cannot disable the default postblit
and still act as a range, correct? Should I be overloading this?
2. Directly related to the above, I need, when the range is
consumed, to free() the underlying library's iterator handle.
Naively, I had the destructor do this, but obviously with
multiple calls to ~this I end up with an error free()'ing a
pointer that is no longer alloc'd. What is the correct way to
handle this situation in D?
Other Range and destructor advice generally (e.g., "You should
totally change your design or approach to X instead") is always
welcomed.
James
What is special about an immutable array of class objects, and why can I not .dup ?
Consider the below:
```
class C
{
int x;
}
struct S
{
int x;
}
void main()
{
immutable C[] c = [ new C(), new C()];
immutable S[] s = [ S(), S() ];
immutable int[] i = [ 1, 2 ];
auto x = c.dup;
auto y = s.dup;
auto z = i.dup;
}
```
This fails to compile with a `.dup` template matching error at
line `auto x = c.dup;`. However, calling `.idup` works just fine.
The immutable struct array and int array of course `.dup` just
fine.
I would have guessed that changing the definition of `C[]` to
`immutable(C)[]` would have also helped, but it did not.
Why are the class objects special in this case, and why does
`immutable(C)[]` not help? I believed that this defined a
dynamic array `c` which was itself mutable, the elements of which
were immutable.
Thanks for insights.
Why does enumerate over range return dchar, when ranging without returns char?
I am puzzled why enumerating in a foreach returns a dchar (which
forces me to cast), whereas without the enumerate the range
returns a char as expected.
Example:
```
import std.stdio;
import std.range : enumerate;
void main()
{
char[] s = ['a','b','c'];
char[3] x;
auto i = 0;
foreach(c; s) {
x[i] = c;
i++;
}
writeln(x);
}
```
Above works without cast.
'''
import std.stdio;
import std.range : enumerate;
void main()
{
char[] s = ['a','b','c'];
char[3] x;
foreach(i, c; enumerate(s)) {
x[i] = c;
i++;
}
writeln(x);
}
```
Above fails without casting c to type char.
The function signature for enumerate shows "auto" return type, so
that does not help me understand.
Kind regards
Re: What is the "right" way to create a generic type getter (and setter) ?
On Wednesday, 14 March 2018 at 22:58:25 UTC, ag0aep6g wrote:
You can probably get around the (manually maintained?) `FIELDS`
array with `.tupleof` or something similar:
static foreach (i, f; S.tupleof)
{
case __traits(identifier, f):
}
Any pointers / design patterns on this particular type of
problem class would be greatly appreciated. (Sidenote, I
realize I could probably use the witchcraft library, but I am
also using this as exercise to learn D beyond the basics).
You simply cannot have a method that returns different types
based on a run-time value. You could possibly return a
std.variant.Variant. But if the goal is just to print the value
to the screen, all you need is a string.
So the signature would be `string get(string field)`. And for
the implementation you could use `.tupleof` to iterate over all
fields, and then return `f.to!string`.
`set` can be done similarly. Take two `string`s: the field
name, and the value. `static foreach` over all fields. On a
match, convert the given value string to the type of the field
that matched.
Thanks - to!string certainly seems to be a good option in this
case (CLI) and I was definitely overthinking this part, perhaps
because I was trying to write everything as generically /
extensibly as possible (for example, to use the same framework
but with a GUI or web front end, for example).
I would still think an AA mapping (string) field name to a type
would be useful and will see if I can construct it as a mixin
using typeof(Struct.member) somehow.
What is the "right" way to create a generic type getter (and setter) ?
For context, please keep in mind I am coming from a python
background, but am very much enjoying strong typing, although it
is taking some significant adjustment.
Suppose I have a struct (which is really a memory map of a data
file I am reading in) with too many data members to reasonably
code getters/setters for by hand. I wish to either retrieve
individual values or set individual values, which could be
numeric, boolean, or string, from the command line, à la:
$ prog -i inputfile.bin get field_name;
(prints "300" or "false" or "Welcome to the jungle")
$ prog -i inputfile.bin set some_field:9000
$ prog -i inputfile.bin set other_field:Whatever_String
Each field itself is strongly typed, for what that's worth.
Approaches I have considered and implemented in part are:
* templated getter (T get(T)(string field) {...}) but this
approach requires knowledge of field types which I cannot
reasonably expect to know at runtime(?)
* modification to the above whereby I could have an AA
holding type information for each field, generated by static
foreach {mixin ...}, although I cannot get this to work as my
struct's static constructor complains (rightly) that it cannot
work without knowing 'this' at compile time. Code:
`mixin("field_types[\"" ~ prop ~ "\"] = typeid(this." ~ prop ~
");");` Is there another __trait I am missing that will give me
the type of the struct member without requiring an instance of
the struct?
I did manage to use metaprogramming inside my templated get
function to handle numeric values, which was fascinating
(although this is probably ugly code and it required a large enum
array FIELDS):
```
GetterSwitch:
switch (field)
{
static foreach(prop; FIELDS ) {
mixin("case \"" ~ prop ~ "\": val = this." ~ prop
~ "; break GetterSwitch;");
}
default:
val = 0;
assert(0); // This is to prevent subtle bugs,
but I need a better error handler
}
```
Any pointers / design patterns on this particular type of problem
class would be greatly appreciated. (Sidenote, I realize I could
probably use the witchcraft library, but I am also using this as
exercise to learn D beyond the basics).
Thanks in advance
James
