Re: Comparing Exceptions and Errors
On Monday, 6 June 2022 at 04:59:05 UTC, Ola Fosheim Grøstad wrote: For instance if a sort function fails, then you can call a slower sort function. Or in terms of actors/tasks: if one actor-solver fails numerically, then you can recover and use a different actor-solver. Those are not places where you would put an assert. The only place to put an assert is when *you* know there is no recovery. Like you have been arguing, there aren't many places like that. So don't use it. --- 9 out of 10 times when I see an assert in code review I ask the author to reconsider. Often it only requires a little tweak. I guess you could say I have found asserts to be misused.
Re: Comparing Exceptions and Errors
On Sunday, 5 June 2022 at 06:31:42 UTC, Ola Fosheim Grøstad wrote: On Sunday, 5 June 2022 at 00:40:26 UTC, Ali Çehreli wrote: That is not very probable in 100% @safe code. You are basically saying that D cannot compete with Go and other «safe» languages. Go has panic. Other languages have similar constructs. So D will never be able to provide actors and provide fault tolerance. I guess it depends on the programmer. Is the service in a usable state? Yes, the actor code failed. The actor code change frequently, not the runtime kernel. The actor code is free to call anything, including @system code. How would the actor framework know when an error is due to a silly bug in an isolated function or if it is something more serious?
Re: Comparing Exceptions and Errors
On Saturday, 4 June 2022 at 17:17:13 UTC, Ola Fosheim Grøstad wrote: Why can't Error unwind the stack properly? It does normally, but it doesn't destruct objects when those are in `nothrow` functions. Nothrow functions don't throw, so have no cleanup. You could argue it is strange that assert throws... In a not-miniscule service you can be pretty certain that some ±1 bugs will be there, especially in a service that is receiving new features on a regular basis. Most wont throw a Error though. And typical services have canary releases and rollback. So you just fix it, which you have to do anyway. Not saying its perfect, but if you only use asserts when you have to, and handle other things using the type system, it doesn't actually happen all that often.
Re: Comparing Exceptions and Errors
On Saturday, 4 June 2022 at 01:17:28 UTC, Steven Schveighoffer wrote: If a thread does not catch an error and end the program, that's a defect in druntime I think. If it tries to rethrow the exception in the main thread (oh, man I have to check... Yeah, this is what it does), then it's entirely possible that the main thread will never even get to the `Error`! Yes, for that reason, and others, people should not use that api. If we are paranoid and want to do as little as possible, at least we should attempt to copy a string literal to stderr. Something like "Thread exiting with Error." And exit(1) right after that. Yes, that is what it should do. Probably yes.
Re: Comparing Exceptions and Errors
On Saturday, 4 June 2022 at 14:19:22 UTC, Ola Fosheim Grøstad wrote: Also, what it is the purpose of @safe if you have to kill all threads? Such rigidity will just make Go look all the more attractive for service providers! I agree with this, but given the current semantics there is nothing else to do but teardown everything upon first sight of Error. The reasoning is simple: Error + nothrow will sidestep any RAII you may have. Since you cannot know what potentially wasn't destructed, the only safe course of action is to abandon ship. Yes, in plenty of cases that is completely overkill. Then again, programs should be written to not assert in the first place. Considering most asserts I have seen are either due to a bad api or just laziness - and shouldn't have to exist in the first place - maybe it's not that bad.
Re: Improve a simple event handler
On Sunday, 16 January 2022 at 20:01:09 UTC, JN wrote:
On Saturday, 15 January 2022 at 23:15:16 UTC, JN wrote:
Is there some way I could improve this with some D features?
My main gripes with it are:
Managed to dramatically simplify it to 10 lines of code with
variadic templates.
```d
import std.stdio;
struct Event(T...)
{
void function(T)[] listeners;
void addListener(void function(T) handler)
{
listeners ~= handler;
}
void emit(T args)
{
foreach (listener; listeners)
{
listener(args);
}
}
}
void onResize(uint newWidth, uint newHeight)
{
writefln("Resized: %d %d", newWidth, newHeight);
}
void main()
{
Event!(uint, uint) windowResizeEvent;
windowResizeEvent.addListener();
windowResizeEvent.emit(1000, 2000);
}
```
I am very happy with this solution.
Looks good. But do note that with larger applications it
inevitably becomes a ball of spaghetti, making it hard to
understand why a certain widget behaves the way it does (or
doesn't).
The other problem - already apparent in this small example - is
the absence of `removeListener`. It is a very crucial and often
overlooked part that often only gets written afterwards. The
problem is that it ties into lifetime which is hard to bolt on.
For small things though, it works wonderfully.
Re: Make sure lifetime of helper structs is less than owning struct
On Monday, 15 November 2021 at 22:49:12 UTC, Ali Çehreli wrote: Trying with it produces an error when 'new' is not used: Error: reference to local variable `file` assigned to non-scope parameter `p` calling deneme.ByChunk.opAssign The error is what the OP wanted, so that is expected. Although, he did ask for it to be on the next line, but this is better since it points exactly to the line where he was escaping a reference to the scoped object. I don't see how it solves the problem. Sebastiaan Koppe might have intended to allocate the object dynamically with 'new' as well? No I didn't. Anything created with new has automatic lifetime. Here the OP wanted to (have the compiler) destroy the FileReader when it left the scope, while disallowing any use after free.
Re: Make sure lifetime of helper structs is less than owning struct
On Monday, 15 November 2021 at 15:56:57 UTC, WebFreak001 wrote:
is this currently possible or maybe possible with DIP1000?
Yes it is. But besides `-dip1000` and `@safe`, it requires the
use of a pointer:
```D
@safe:
struct ByChunk {
FileReader* r;
void popFront() {}
}
struct FileReader {
ByChunk byChunk() return scope {
return ByChunk();
}
}
void main() {
ByChunk helper;
{
auto file = FileReader();
helper = file.byChunk; // Error: address of variable `file`
assigned to `helper` with longer lifetime
}
helper.popFront;
}
```
Re: auto ref function parameter causes that non copyable struct is copied?
On Tuesday, 9 November 2021 at 19:30:20 UTC, tchaloupka wrote:
On Monday, 8 November 2021 at 23:26:39 UTC, tchaloupka wrote:
Bug or feature? :)
I've reported it in
https://issues.dlang.org/show_bug.cgi?id=22498.
It doesn't copy. It just destructs the same object twice... Ouch.
Change the destructor to `~this() { printf("~this(%d)\n", n); n =
12; }` and you'll see.
I have been looking at LDC's IR of this. `unwrap` takes a lvalue,
but the compiler puts the object from `gen` on main's stack and
gives a pointer to unwrap instead. `unwrap` is now the sole owner
of the object, and calls the destructor before returning a ref to
one of its fields.
I haven't figured out the interplay of features and optimizations
here, but it looks like a leak. I would have expected @safe to
catch this.
As you said in the bug, NVRO solves it (not sure why). As well as
not passing a lvalue into `unwrap` in the first place.
Re: Threading challenge: calculate fib(45) while spinning
On Friday, 15 October 2021 at 03:35:44 UTC, jfondren wrote:
The book, "The Go Programming Language" has this simple
goroutine example:
[...]
Here is a similar implementation using the concurrency library:
```d
import concurrency;
import concurrency.stream;
import concurrency.sender : justFrom;
import concurrency.operations : via, race;
import concurrency.thread : ThreadSender;
import core.time : msecs;
import std.stdio : writef, writefln, stdout;
import core.thread : Thread;
void main() @safe {
enum chars = `-\|/`;
auto spinner = infiniteStream(0)
.scan((int acc, int _) => acc + 1, 0)
.collect((int i) shared @trusted {
writef("\r%c", chars[i % chars.length]);
stdout.flush();
Thread.sleep(100.msecs);
})
.via(ThreadSender());
enum n = 45;
auto work = justFrom(() => fib(n));
auto result = race(spinner, work).syncWait.value;
writefln("\rFibonacci(%d) = %d", n, result.get);
}
int fib(int x) pure @safe @nogc {
if (x < 2)
return x;
return fib(x - 1) + fib(x - 2);
}
```
Go has language support so it is a bit unfair to compare it.
But this code will properly handle errors (in case `writef` or
`flush` throws), and as well as having an explicit
synchronization point so that the final `writeln` is always after
the spinner is done.
Re: to compose or hack?
On Wednesday, 7 July 2021 at 13:30:28 UTC, Steven Schveighoffer
wrote:
On 7/7/21 5:54 AM, rassoc wrote:
On Wednesday, 7 July 2021 at 01:44:20 UTC, Steven
Schveighoffer wrote:
So I have this situation where I need to split a string, then
where the splits are, insert a string to go between the
elements making a new range, all without allocating
(hopefully).
Without considering the more general case, isn't that just
splitter-joiner?
No, splitter-joiner would make a range of characters, I want a
range of strings.
Just lift each item in a range then:
```d
import std;
auto foo(string s, string sp, string j) @nogc {
return s.splitter(sp).map!(i => only(i)).joiner(only(j));
}
void main() {
foo("ab,cd,ef,gh", ",", "##").writeln; // => ["ab", "##",
"cd", "##", "ef", "##", "gh"]
}
```
Re: GC memory fragmentation
On Sunday, 11 April 2021 at 09:10:22 UTC, tchaloupka wrote: Hi, we're using vibe-d (on Linux) for a long running REST API server and have problem with constantly growing memory until system kills it with OOM killer. [...] But this is very bad for performance so we've prolonged the interval for example to 30 seconds and now memory still goes up (not that dramatically but still). [...] So it wastes a lot of free space which it can't return back to OS for some reason. Can these numbers be caused by memory fragmentation? There is probably a lot of small allocations (postgresql query, result processing and REST API json serialization). We have similar problems, we see memory usage alternate between plateauing and then slowly growing. Until it hits the configured maximum memory for that job and the orchestrator kills it (we run multiple instances and have good failover). I have reduced the problem by refactoring some of our gc usage, but the problem still persists. On side-note, it would also be good if the GC can be aware of the max memory it is allotted so that it knows it needs to do more aggressive collections when nearing it.
Re: C++ or D?
On Thursday, 31 December 2020 at 16:03:54 UTC, Ola Fosheim Grøstad wrote: On Thursday, 31 December 2020 at 14:56:37 UTC, Sebastiaan Koppe wrote: It could take a few years indeed, but what will D do in that same time window? What would you like to see? For shared to mean something. Stackless coroutines. Compile-time lifetime management, i.e. better ways to define ownership.
Re: C++ or D?
On Thursday, 31 December 2020 at 09:57:01 UTC, Imperatorn wrote: On Thursday, 31 December 2020 at 07:32:31 UTC, RSY wrote: Sorry for the spam, but this is because of people like him that people like me (i discovered D recently) that can't be aware of why D is a great language They diminish all arguments that makes D better than alternatives You guys have to help me fight that kind of behavior, because it doesn't help D, as if it was their goal, do they want to make sure D doesn't eat specific market share, so some other language can? fishy fishy But they should be aware that C++ *as a language* has a long way to go before it gets all the features etc that D has. Maybe 2023, maybe 2027, who knows. Maybe that's fine for them, but not for me. Au contraire; I find that C++ has modernised relatively successful and has a lot of great proposals in the pipeline. Of course they may all get rejected, but even if only some of them get accepted, C++ starts to have a leg up on D in my opinion. It could take a few years indeed, but what will D do in that same time window?
Re: Writing a really fast lexer
On Saturday, 12 December 2020 at 18:15:11 UTC, vnr wrote: Yes, I know Pegged, it's a really interesting parser generator engine, nevertheless, the grammar of what I would like to analyse is not a PEG. But I am also curious to know the performances of this tool for very large inputs. The performance of pegged isn't great. Neither memory nor cpu wise. In many cases that is fine though, but if you are performance sensitive, you should look elsewhere. I did a full JS grammar in pegged, but switched to a handwritten one when I realised its poor performance.
Re: Help on asdf json module
On Sunday, 25 October 2020 at 06:05:27 UTC, Vino wrote:
Hi All,
Currently we are testing various json module such as
"std.json, std_data_json, vibe.data.json and asdf", the below
code works perfectely while use "std_data_json or
vibe.data.json" but not working as expected when we use "asdf"
and throwing the below error, hence request your help on the
same.
The API's are different. You can't just expect one to work with
the api of the other.
Asdf is a bit more strict in that you have to specify whether you
intent to iterate a json object (with `.byKeyValue()`) or a json
array (with `.byElement()`).
Also the way you fetch values out of it is different. There is
`.get!T(default)` that requires a default value in case it is
empty (undefined), or `cast(T)field` if you assume there is a
value and want an exception throw if not.
/+dub.sdl:
dependency "asdf" version="~>0.6.6"
+/
import std.stdio: writeln;
import asdf;
import std.conv: to;
void main()
{
string apidata =
`{"items":[{"name":"T10","hostname":"test1","type":[{"typeValue":"TD,d...@dev.com,DEVt"},{"typeno":"000"}]},{"name":"T11","hostname":"test2","type":[{"typeValue":"TF,q...@qas.com,QAS"},{"typeno":"100"}]},{"name":"T11","hostname":"test3","type":[{"typeValue":"TP,p...@prd.com,PRD"},{"typeno":"101"}]}]}`;
auto jv = parseJson(apidata);
foreach(j; jv["items"].byElement()){
writeln(j["name"].get!string("default"));
}
}
Re: A scheduled control signal with fibers?
On Friday, 25 September 2020 at 13:08:16 UTC, Sebastiaan Koppe wrote: On Friday, 25 September 2020 at 11:58:53 UTC, Ferhat Kurtulmuş How can I implement schedulePWMSignalToValve(pwmval, afterNmilliseconds ) using fibers? No need for fibers per se. Can also use https://code.dlang.org/packages/timingwheels
Re: A scheduled control signal with fibers?
On Friday, 25 September 2020 at 11:58:53 UTC, Ferhat Kurtulmuş
wrote:
int main(){
...
while(true){
int pwmval = getFlameIntensityViaImageProcessing();
sendPWMSignalToValfe(pwmval); // I need this streamed
ctrl signal to the valfe with a delayed time shift
// a possible solution:
// enum afterNmilliseconds = 1500;
// schedulePWMSignalToValve(pwmval, afterNmilliseconds
);
...
}
...
}
How can I implement schedulePWMSignalToValve(pwmval,
afterNmilliseconds ) using fibers?
Thanks in advance.
No need for fibers per se.
You can run 2 threads. One that produces {time: now + 1500.msecs,
value: getFlameIntensityViaImageProcessing} objects and one that
consumes those and basically waits until each's msg.time < now
and then sendPWMSignalToValfe(msg.value). You would basically
rely on std.concurrency's MessageBox to do the queuing. Although
you could do that manually as well.
Could also run it on 1 thread if you don't mind there being a
jitter of however long getFlameIntensityViaImageProcessing takes,
but you will need a queue.
Re: SIGUSR1 in clock_nanosleep()? how to isolate this issue?
On Thursday, 20 August 2020 at 18:58:43 UTC, mw wrote: Hi, I run into an issue: it's SIGUSR1 in clock_nanosleep() [...] Anyone has some suggestions on how to isolate this issue? Thanks. Try "handle SIGUSR1 nostop noprint" and "handle SIGUSR2 nostop noprint" in gdb.
Re: Vibe.d and NodeJs with Express
On Sunday, 12 July 2020 at 10:01:54 UTC, greatsam4sure wrote: I am thinking of building an App with Vibe. D or NodeJS but my topmost priority is speed and ease of development due to third party libraries integration. How much speed do you need? I doubt you really need every last millisecond, at which point ease of development takes over. Instead it might be better to look at which third party libraries you need. D has got most you need but you might end up needing something which isn't there. If you are ready to code that yourself then go for D for sure. My question is can I eat my cake and have it if I go with Dlang and Vibe. D. I have being able to use jQuery and bootstrap with vibe. D and it work well. If the app stays small that can work but you can also look at something a bit more modern. Angular, react, vue or svelte, there are plenty to pick from. My believe is that most JavaScript library will work with Vibe. D out of the box. Of course. You just end up writing an rest or graphql backend in D and connect it to a frontend.
Re: Web Assembly, struct to JavaScript Object and back
On Tuesday, 23 June 2020 at 18:15:25 UTC, tirithen wrote: Anyone that has something similar working with struct objects? Passing anything besides int/double/bool between JS and wasm is hard work. Currently the ABI generated by LDC is so that arguments besides int/double/bool (and array/delegates are special too) are passed by pointer. So if you want to call a wasm function that expects a struct, you instead pass a pointer to wasm memory where you have encoded that struct. Similarly if you want to call a js function with rich objects you have to do some handling on the JS side. Return values other than int/double/bool from wasm functions are special and it is expected that the function is called with a pointer as first argument. There are a few gotcha but this basically describes it. In https://github.com/skoppe/spasm I am using this approach as well. Except I don't actually move D struct to and from JS, instead only references to JS objects, strings, delegates, unions and arrays. Same principle applies though.
Re: called copy constructor in foreach with ref on Range
On Tuesday, 23 June 2020 at 07:30:29 UTC, Stanislav Blinov wrote: On Tuesday, 23 June 2020 at 05:24:37 UTC, H. S. Teoh wrote: I'm also wondering what's the motivation behind supporting non-copyable ranges, and whether it's worth the effort and inevitable complications to support it if it's a rare use-case. Do you have any compelling use-case in mind, that might make this worthwhile? This compelling use case is staring at us from comments in this very thread. I am a bit on the fence about having input ranges be non-copyable. Initially I liked the idea very much; I am a big fan of 'unique' semantics. But just because most people don't expect hot/destructive reads, doesn't mean we should impose such a hard restriction on input ranges. There are use cases for popping from an input range from different places. An obvious one would be parsing data from the network, where you pass the input range into helper functions that parse sub-sections of the data. They can be made to work for sure, but it doesn't make it cleaner. On the other hand, most of the time, non-copyable is exactly what you need...
Re: how to achieve C's Token Pasting (##) Operator to generate variable name in D?
On Saturday, 30 May 2020 at 23:39:31 UTC, mw wrote:
Am I doing the right thing in D? any improvement you'd suggest?
e.g. I don't quite like have to put the type and var name in
the quotes as string:
mixin(RW!("int", "x"));
Is there a better way to achieve this? esp. for the type `int`,
is there any way I don't have to quote it as string?
Thanks.
This would also be an option.
```
import std;
class Point {
struct Inner {
int x;
double y;
}
private Inner inner;
Point opDispatch(string name, T)(T value) {
mixin("inner."~name~" = value;");
return this;
}
auto opDispatch(string name)() {
mixin("return inner."~name~";");
}
}
void main()
{
Point b = new Point();
b.x(4).y(5.0);
writeln(b.x);
}
```
Re: D and Async I/O
On Thursday, 14 May 2020 at 09:36:33 UTC, Russel Winder wrote: Whilst C frameworks use callbacks and trampolines, high level languages seem to be basing things on futures – or things that are effectively isomorphic to futures. What I find most lacking is proper cancellation. Also, futures are eager. Concurrency and parallelism will never be solved problems I suspect, but I think there is a fairly good consensus now on what is state of the art. I haven't found a language that ticks all the boxes. Kotlin comes close. I think there are a lot of lessons to be learned from all the efforts in the programming community. We should: - get stackless coroutines - get structured concurrency - steal as many idea from the C++'s executors proposal (http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2020/p0443r13.html) I am not convinced C++ has the best "state of the art" in this respect – after all it is just copying what JVM languages have had for ages, and Rust updated for modern native code languages. I am not sure you have read the proposal. Initially I brushed it off, but upon closer inspection I realised there are some gems in there.
Re: D and Async I/O
On Tuesday, 12 May 2020 at 09:23:40 UTC, Russel Winder wrote: On Mon, 2020-05-11 at 19:34 +0200, Jacob Carlborg via Digitalmars-d-learn wrote: On 2020-05-11 16:44, Russel Winder wrote: > Crickey, a third option. This wil increase my dithering! ;-) Forth: Mecca [1] :) [1] https://github.com/weka-io/mecca Hummm… it seems everyone who needed async activity and particularly I/O in D has written their own. Mostly along with all their own data structures and algorithms library. Yeah it is a shame, but you see it in almost every language. Probably means concurrency and io isn't a fully solved problem yet. I keep trying to come back to D for GTK+ working, but in the end I keep going back to Python and Rust because D has no futures, and no added extras over GtkD auto translation of the GTK+ API to make it D-y in the way gtk-rs make GTK+ Rust-y. Sorry for the apparent gloom, I just felt the need to tell it how I feel. I think there are a lot of lessons to be learned from all the efforts in the programming community. We should: - get stackless coroutines - get structured concurrency - steal as many idea from the C++'s executors proposal (http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2020/p0443r13.html)
Re: Best way to learn 2d games with D?
On Tuesday, 17 March 2020 at 18:55:08 UTC, Steven Schveighoffer wrote: He's done a lot of stuff in Scratch. I taught him and a whole group of other homeschoolers a class on javascript and this year (up until this whole virus thing) we were working in Roblox (lua). So far I try to make the lessons not so much about the language or the environment, but the code concepts. I don't really love the scratch methodology of dumbing down everything, I feel like it limits too much and doesn't help you enough to learn necessarily the parts of programming that transfer to all other programming languages. Yes, it has loops, yes it has data (though it's really convoluted), but it's not going to transfer to real-world coding. It looks like gamemaker is along the same lines "write games without ever having to code" seems like it defeats the purpose of what I'm trying to do ;) Dont trust that marketing, there is actually decent scripting in gamemaker, which you'll need if you get creative. Plus plenty of good example games that are also quite playable.
Re: Best way to learn 2d games with D?
On Tuesday, 17 March 2020 at 15:38:55 UTC, Steven Schveighoffer wrote: It's not something I'm intending to create professionally, really the impetus is my son wanting to do more significant game coding. -Steve How old is he? I find something simple like gamemaker works well with 12-16 olds.
Re: Best way to learn 2d games with D?
On Sunday, 15 March 2020 at 17:58:58 UTC, Steven Schveighoffer wrote: I want to try and learn how to write 2d games. I'd prefer to do it with D. No resources but I remember the serpent framework mentioned on this forum here recently. It looks pretty decent. https://github.com/lispysnake/serpent
Re: Idiomatic way to express errors without resorting to exceptions
On Saturday, 7 March 2020 at 15:44:38 UTC, Arine wrote: I feel as though that's it's greatest weakness. It makes the check whether there is or isn't a value hidden. The case when there isn't a value should be handled explicitly, not implicitly. Propogating a None value isn't useful and is computationally demanding as each subsequent call will need to do a check to see if it has a value as it results in an optional type (for binary operators). So something like `a + b * c` is now much more expensive than it appears. This is exactly the kind of abuse of operator overloading that the feature is shunned for. What can I say? If you don't like the semantics, don't use it. I have found value in it. Anyways not sure what you mean here with the code below. If "first" here returns an optional type, you can't call "doSomething" like that without first checking if the value exists. Optional just doesn't allow it and Nullable will throw an exception. ``` list.first.doSomething(); // error ``` You are right. Nowadays you need a `.oc` call in between. Also, doSomething cannot be a free-standing function (sadly).
Re: Idiomatic way to express errors without resorting to exceptions
On Saturday, 29 February 2020 at 13:40:11 UTC, Adnan wrote: On Saturday, 29 February 2020 at 13:03:21 UTC, Sebastiaan Koppe wrote: On Saturday, 29 February 2020 at 12:50:59 UTC, Adnan wrote: * Option!T from the optional package: Has even worse problem IMO. Not only it allows None + int but also it returns a `[]`. This API is not to my liking. You could say well Haskell has fmap for Optional etc, and I am aware of that, so does Rust with map etc. But I am talking about basic things: like `+`. I would argue it is one of its strengths. Doesn't that pretty much defeat the entire purpose of type-guarding a potentially error/absent value? Like I said, I don't use optionals when I care about errors. That is not what they are designed for. If I want to type-guard potential errors I will use SumType!(T, Error). It forces you to handle both cases, either at compile time (with the match template), or at runtime (with the tryMatch template). The power of optionals, however, lies in the following: ``` list.first.doSomething(); ``` Here doSomething will only be called when the list contains at least one item. Here I don't care about cases where the list is empty, I just want to doSomething if it isn't.
Re: Idiomatic way to express errors without resorting to exceptions
On Saturday, 29 February 2020 at 12:50:59 UTC, Adnan wrote: * Option!T from the optional package: Has even worse problem IMO. Not only it allows None + int but also it returns a `[]`. This API is not to my liking. You could say well Haskell has fmap for Optional etc, and I am aware of that, so does Rust with map etc. But I am talking about basic things: like `+`. I would argue it is one of its strengths. Regardless, I don't think option/nullable/maybe is a good type for errors. Rather you should use something like SumType!(T, Error), or any other 'either' type.
Re: Some impressions/notes from a new D programmer
On Wednesday, 12 February 2020 at 18:39:36 UTC, Steven Schveighoffer wrote: On 2/12/20 10:52 AM, mark wrote: I also think you split into more HTML files which I prefer. FYI, dlang.org has a secondary version of the docs which splits the documents up more: https://dlang.org/library/index.html I can't find a link to it directly from the main page though... This version is based on ddox (http://code.dlang.org/packages/ddox) -Steve There is also devdocs.io It has many languages and frameworks. The beauty is that it caches in local storage so searches are super fast and it is also available offline. Their d version lags a tiny bit, but that is fine.
Re: Does D have an equvalent of: if (auto = expr; expr)
On Friday, 7 February 2020 at 08:52:44 UTC, mark wrote:
Some languages support this kind of thing:
if ((var x = expression) > 50)
print(x, " is > 50")
Is there anything similar in D?
Yes and no.
It only works for bools or things that convert to bool.
You might have seen:
string[string] dict;
if (auto p = "key" in dict) {
writeln(*p);
}
That works because the 'in' operator on aa's returns a pointer,
which can be compared to bool.
Re: Mix struct types in the same array
On Wednesday, 18 December 2019 at 22:00:20 UTC, tirithen wrote: I want to have a array/list/queue of instances of various struct types that represent events. How can I achieve that? With classes I would have interfaces I guess, but I want to use structs if possible as they seem less complex (and faster?). Can I wrap each struct with in another struct called something like Entry that in turn can contain the event struct some how, or will that just move the problem? If you know all types up front you can use the Sumtype library on code.dlang.org
Re: Troubleshooting DUB invocations
On Tuesday, 19 November 2019 at 12:06:36 UTC, Dukc wrote: On Monday, 18 November 2019 at 19:35:13 UTC, Sebastiaan Koppe wrote: Well yes. But that is just the way things worked up until now, ldc and dub just pick the host machine. Luckily there is the new dub `--arch` argument that can take a llvm triple, in our case wasm32-unknown-unknown-wasm. This causes dub not to add the `--no-as-needed`. That was news to me - I thought everything was always being compiled to WASM. Well it is, but some versions from the host were still set. E.g. version(linux). Except, that it also passes the triple upwards the dependency tree. Now all the dependencies of spasm get compiled targeting wasm. This is a good thing, except that the optional package which spasm depends on fails to compile with it. There is a newer version that fixes the configuration, but that one fails because of the `from.std` import idiom (it imports the std package from phobos which doesn't recognise wasm and fails with "Unknown OS"). I have sometimes thought that perhaps a static assert isn't the best thing to use for unimplemented features in Phobos, precisely because of this issue. A @disabled function stub would serve better, unless I'm missing something. Either way, as long as there is a clear way to debug why it ended up there. Unlike what we have now where you need to dig endlessly. "ending up"? If it's like what getting Phobos to work has been for me, you're continuing the game, not ending up playing it ;D. Yeah it is a pain, and since wasm/betterc isn't tested (or barely), anyone is free to break it. E.g. the recent change to the std.range.chain function, which suddenly wasn't betterC anymore... Another workaround that you can use right now is by adding the `--build-mode=allAtOnce` argument to dub. It effectively gets you the old behaviour. It is what I am using in my CI to get it to go green again. Do not hurry more than you want -I already got my extract-dub-failure workaround working. Sure, but stuff just needs to work. I updated the BUILDING.md file in spasm as well.
Re: Troubleshooting DUB invocations
On Wednesday, 13 November 2019 at 18:10:15 UTC, Dukc wrote: On Wednesday, 13 November 2019 at 15:41:01 UTC, Sebastiaan Koppe wrote: It has been on the back of my mind since 1.18-beta came out. I am going to reserve a little time tomorrow to work on it. Regarding that, perhaps I can save you a bit trouble if you also try to get 1.19 working: if you get compile errors related to SortedRange, the fix is https://github.com/dlang/phobos/pull/7266. I have had some time today to look into this. About the --no-as-needed: TL;DR: add `--build-mode=allAtOnce` to the dub command. Kinke made some changes in dub to facilitate separate linking for ldc. I am not aware of all the details but the major benefit is that it allows cross compilation with dub and ldc. Because of the separate linking the --no-as-needed turned up. As far as I can see it is only needed when compiling for linux. Which brings up the question, why linux? Aren't we compiling for wasm? Well yes. But that is just the way things worked up until now, ldc and dub just pick the host machine. Luckily there is the new dub `--arch` argument that can take a llvm triple, in our case wasm32-unknown-unknown-wasm. This causes dub not to add the `--no-as-needed`. Except, that it also passes the triple upwards the dependency tree. Now all the dependencies of spasm get compiled targeting wasm. This is a good thing, except that the optional package which spasm depends on fails to compile with it. There is a newer version that fixes the configuration, but that one fails because of the `from.std` import idiom (it imports the std package from phobos which doesn't recognise wasm and fails with "Unknown OS"). In the end it is all caused by phobos and druntime not knowing anything about wasm. Which I am currently working on behind the scenes to fix. In the meantime I am going to make a PR for the optional package to avoid the `from.std` idiom. Although I might end up playing whack-a-mole here, as there might be more dependencies that need a fix now. Another workaround that you can use right now is by adding the `--build-mode=allAtOnce` argument to dub. It effectively gets you the old behaviour. It is what I am using in my CI to get it to go green again.
Re: Troubleshooting DUB invocations
On Tuesday, 12 November 2019 at 16:44:06 UTC, Dukc wrote: When trying to compile a project including newest Spasm (DUB package) using the newest LDC via DUB, the result is: ``` lld: error: unknown argument: --no-as-needed ``` I then ran DUB with -v switch and it turned out the invocation contained `-L--no-as-needed` as first of all the -L arguments. The trouble is, how do I know what causes DUB to add that argument to the invocation? I could find no reason in `dub.` files of either my package, Spasm or any package in Spasm dependency tree. I have seen this error as well. I actually test a few ldc versions on the CI, and I always test latest. Currently anything higher than 1.17 is not supported, although it would probably require a small change. Except for the fact that -mtriple gets propagated starting from 1.18 to all dependencies (which is a good thing). This causes issues for some of the dependencies since they have no idea what wasm is. It has been on the back of my mind since 1.18-beta came out. I am going to reserve a little time tomorrow to work on it. Thanks for digging as far as you have.
Re: Dub and gitsubmodules
Thanks for the replies!
Dub and gitsubmodules
Does anyone know a reliable way of having a dub package that contains git submodules and is to be used as a dependency? I am looking for a way to ensure the submodules are initialised before a build.
Re: Alternative to C++ macro in D
On Sunday, 3 November 2019 at 16:55:36 UTC, Vinod K Chandran
wrote:
int main() {
log("Trying to avoid the visual clutter aused by closing
curly braces") ;
string myStr = "Now, code looks more elegant" ;
log(myStr) ;
wait ;
end
How can i do this in D ? Especially the " #define end }; ".
I've tried " alias end = } " but didn't worked.
You can't. D deliberately doesn't have a preprocessor. `#define
end };` is one of the reasons.
Re: Mixin and introspection ordering
On Tuesday, 15 October 2019 at 19:50:33 UTC, Paul Backus wrote: On Tuesday, 15 October 2019 at 19:19:58 UTC, Sebastiaan Koppe wrote: You would expect 2 to print `tuple(a)` as well, but it doesn't. Don't know if it is a bug. Any time you use a construct that mutates the AST (template mixin, string mixin, static if, static foreach), it's possible to catch it in both "before" and "after" states. For example: This can cause some "interesting" things to happen when using templates like the ones in std.traits to do reflection, since the result of template instantiation is cached: Wth the simple examples in this thread it can even be excused. However, when the mixin and the introspection are part of something larger it is no longer easily apparent. I myself spend 30min wondering why it didn't work. And I wrote it myself. Do we want to be able to catch things in their 'before' state? Or is it a bug?
Mixin and introspection ordering
Sometimes ordering is important when combining mixins and
introspection, this is another such case:
```
import std.traits;
enum myuda;
mixin template Slot(string name) {
mixin("@myuda int "~name~";");
}
struct OuterOption {
mixin Slot!"a";
}
struct App {
pragma(msg, getSymbolsByUDA!(OuterOption, myuda).stringof);
// 1. prints 'tuple(a)'
// pragma(msg, getSymbolsByUDA!(InnerOption, myuda).stringof);
// 2. prints '()'
struct InnerOption {
mixin Slot!"a";
}
pragma(msg, getSymbolsByUDA!(InnerOption, myuda).stringof);
// 3. prints 'tuple(a)'
}
```
You would expect 2 to print `tuple(a)` as well, but it doesn't.
Don't know if it is a bug.
Re: How to use xargs to remove whitespaces (Dub executable path)
On Wednesday, 4 September 2019 at 05:52:12 UTC, Andre Pany wrote: Hi, I try to get the executable path from a dub package using this command: dub describe dscanner --data=target-path,target-name --data-list | xargs But the output always contains a space between target-path and target-name: /home/user/.dub/packages/dscanner-0.8.0/dscanner/bin/ dscanner How can I get the full path without a space on a debian system in a 1 liner? Kind regards André What about this? dub describe scanner --data=target-path,target-name --data-list --data-0 | tr -d '\0' or if you have jq installed: dub describe dscanner | jq '.targets[0].buildSettings | "\(.targetPath)/\(.targetName)"'
Re: How should I sort a doubly linked list the D way?
On Tuesday, 13 August 2019 at 18:28:35 UTC, Ali Çehreli wrote: On Tuesday, 13 August 2019 at 14:04:45 UTC, Sebastiaan Koppe > wrote: > Convert the nodes into an D array, sort the array with > nodes.sort!"a.x < b.x" and then iterate the array and repair > the next/prev pointers. If possible, I would go further and ditch the linked list altogether: Just append the nodes to an array and then sort the array. It has been shown in research, conference presentations, and in personal code to be the fasted option is most (or all) cases. Yeah, very likely. Although in this case there already is an array; it's going to be close :)
Re: How should I sort a doubly linked list the D way?
On Tuesday, 13 August 2019 at 09:48:52 UTC, Mirjam Akkersdijk wrote: and I would like to sort based on Node.t, how should I tackle it, preferably without resorting to C libraries? Convert the nodes into an D array, sort the array with nodes.sort!"a.x < b.x" and then iterate the array and repair the next/prev pointers.
Re: vibe / self contained standalone executable?
On Sunday, 28 July 2019 at 14:42:48 UTC, Robert M. Münch wrote:
On 2019-07-28 14:14:06 +, Sebastiaan Koppe said:
I am using
https://dlang.org/spec/expression.html#import_expressions for
text files. Don't know if it works on binary files as well.
And this works than good together with the vibe framework? So,
it's not requiring or forcing one to use files or databases?
Haven't tested it, but something like this:
---
import vibe.core.core : runApplication;
import vibe.http.server;
void handleRequest(scope HTTPServerRequest req, scope
HTTPServerResponse res)
{
if (req.path == "/file.txt")
res.writeBody(import("file.txt"), "text/plain");
}
void main()
{
auto settings = new HTTPServerSettings;
settings.port = 8080;
settings.bindAddresses = ["::1", "127.0.0.1"];
auto l = listenHTTP(settings, );
scope (exit) l.stopListening();
runApplication();
}
---
Of course you may want to use the router or the rest generator
for this. See the examples in the repo.
Re: vibe / self contained standalone executable?
On Sunday, 28 July 2019 at 13:45:50 UTC, Robert M. Münch wrote: Is it possible to pack a complete "web-app" (serving web-pages and providing REST API) into a single executable so that no other files need to be accessed and everything is servered from something like a "virtual filesystem" which is in memory only? I am using https://dlang.org/spec/expression.html#import_expressions for text files. Don't know if it works on binary files as well.
Re: can not find the error: Error: TypeInfo cannot be used with -betterC
On Wednesday, 17 July 2019 at 15:52:39 UTC, Newbie2019 wrote: when build my project with -betterC, it throw this error: Error: TypeInfo cannot be used with -betterC There is no location information about it, how can I find what code cause this ? With ldc I often use -v to get the verbose output of the compiler. It will output what module it is compiling and in what stage. Often the module right before the error is the one you'll need to examine. I know, it stinks. Most often it is one of: arrays, ~=, typeid, throw, new, toString.
Re: Reading .pem files for secured
On Thursday, 6 June 2019 at 11:08:18 UTC, Dukc wrote: We were both wrong :-). It turned out that the correct way to initialize a SecureD RSA private key is to feed contents of .pem in without ANY processing. Ah, they made it even easier :)
Re: Reading .pem files for secured
On Friday, 31 May 2019 at 10:35:46 UTC, Dukc wrote: The key pair needs to be persistant between, so I made a 4096-bit private key with OpenSSL, stored in .pem file. Then I constructed a public key from the private one, again with OpenSSL. It seemed strange to me that I could generate a public key afterwards with the private key, instead of having to do both at the same time. I just thought that perhaps crypto is somehow cryptic enough to do that. The public key can always be constructed from the private key. But then came a problem that I need to feed the key from .pem to initialize RSA class. Just base64 decode the PEM data (without the ) and feed it to RSA.this(ubyte[] publicKey). Ought to be that simple. Disclaimer: I have only used openssl directly. No experience with SecureD.
Re: OT - Git training Lon/HK and book recommendation on taste in programming
On Wednesday, 1 May 2019 at 09:51:01 UTC, Laeeth Isharc wrote: Hi. First question - can anyone recommend git / Gitlab training providers in HK and London? Two distinct audiences - highly intelligent people that may or may not really program, and experienced developers with a finance background that could benefit from knowing how to use git properly (finance is often in the dark ages). Can't recommend anyone in particular, but I would recommend to do some interactive challenges at some point. Instruqt is a good one. It has a section on git. https://instruqt.com/public/topics/getting-started-with-git . It is fun and can give you insights who is picking up the material and who is lagging behind. Second question. Lots of people these days start to program to solve their problems at work but they may never have been shown the basic principles of design, structuring and maintenance of their code. If I could give them one book (and a few YouTube links) what should it be ? 'Code Complete' is always good. And there are plenty of MIT courses online of course, like: https://www.youtube.com/watch?v=ytpJdnlu9ug=PLUl4u3cNGP63WbdFxL8giv4yhgdMGaZNA (6.0001 Introduction to Computer Science and Programming in Python. Fall 2016). Also, there are ones from the 80's, they have a certain quality, a certain rigor that I fail to find in more recent lectures.
Re: Operator Overloading with multiple return types
On Friday, 15 March 2019 at 21:35:12 UTC, eXodiquas wrote: Is there any way to achive this behaivour with D2? Yep. Just make the return type in the function declaration `auto`. You are then free to return a different type in each static branch.
Re: AliasSeq in UDA
On Sunday, 10 March 2019 at 16:46:43 UTC, Basile B. wrote: Yes I see. I've refined a bit the test case and maybe I'll took a look this week. Cool. Is it normal to create a testcase that doesn't depend on phobos? I suppose it is needed for it to be included in dmd's testcases.
Re: AliasSeq in UDA
On Sunday, 10 March 2019 at 13:41:32 UTC, Basile B. wrote:
It looks like a bug, a "reject-valid" one.
Try the same code with
enum A = 0;
and it work, despite of B being still opaque. The problem may
be related to the fact the enum A in the orginal code is opaque
and has not type.
Thanks. The example I posted was a reduced case, but I can still
use your trick to fool the compiler.
The following is more real:
---
import std.meta;
enum A; enum B; enum Dummy = 0; // <- Dummy needs to be 0
struct Param(alias T) {}
@AliasSeq!(Dummy,Param!A,Param!B) // <- Here Dummy is needed
struct Foo {}
pragma(msg, __traits(getAttributes, Foo));
void main() {}
---
I have created an issue:
https://issues.dlang.org/show_bug.cgi?id=19728
AliasSeq in UDA
The compiler complains about `cannot form tuple of tuples`
whenever I try to put an AliasSeq in a UDA and try to use it.
You would expect the compiler to expand it. Is this a bug?
---
import std.meta;
enum A; enum B;
@AliasSeq!(A,B) // <-- Error: cannot form tuple of tuples
struct Foo {}
pragma(msg, __traits(getAttributes, Foo)); // <- must be present
(error happens only when queried)
void main() {}
---
link to run.dlang.io:
https://run.dlang.io/gist/cd5cd94d8ce5327e8a7d5ad77f1d15b8
Re: Phobos in BetterC
On Saturday, 9 March 2019 at 17:14:37 UTC, 9il wrote: It was fixed to be used in BetterC. If it still does not work you can open an issue and ping me (@9il). That is awesome. I suppose support for betterC is only from v3 upwards?
Re: Phobos in BetterC
On Friday, 8 March 2019 at 09:24:25 UTC, Vasyl Teliman wrote: Also I would to know what parts of Phobos are available there (e.g. std.traits, std.typecons...). There is no clear rule on which phobos packages work and which don't. It all depends on what underlying features the phobos package uses. Here is the list of what's not allowed in betterC: - Garbage Collection - TypeInfo and ModuleInfo - Classes - Built-in threading (e.g. core.thread) - Dynamic arrays (though slices of static arrays work) and associative arrays - Exceptions - synchronized and core.sync - Static module constructors or destructors Generally anything meta/compile-time works. Packages like std.traits / std.meta / std.range / std.algorithm are not an issue. You would expect std.typecons.tuple to work as well, but it doesn't. If you are doing ctfe, then you are in for a bummer. Because the same restrictions apply there as well. There is supposed to be a workaround by including the ctfe file in question via -I on the command line, but I could never make it work in dub. If you encounter something that doesn't work, there are a couple of options. Sometimes the function you are trying to use is betterC compatible but is inside a package that isn't. Just extract it into a separate file. At other times it is because the struct has a toString method, or throws an exception. Again, copy the relevant part, rip out the toString method and/or replace the exception with an assert (of course, after you make sure the assert doesn't get triggered). There might also be the option to use @nogc exceptions (dip 1008), but I am not sure. If all that isn't possible, you will have to rewrite the thing in question.
Re: pragma mangle on extern(C) in function body
On Wednesday, 16 January 2019 at 19:59:02 UTC, Steven
Schveighoffer wrote:
I'm guessing it's a missed case in the compiler, and not
intentionally omitted.
-Steve
The workaround is quite silly. Seems like a parser issue.
---
pragma(mangle, "Foo")
extern(C) void foo();
mixin template T()
{
pragma(mangle, "Bar")
extern(C) void bar();
}
void main() {
mixin T!();// Hurrah!
}
---
Re: pragma mangle on extern(C) in function body
On Wednesday, 16 January 2019 at 19:41:04 UTC, Sebastiaan Koppe
wrote:
While it is perfectly ok to define an extern(C) function in a
function method, I can't seem to get pragma(mangle, "...") on
it to work.
---
pragma(mangle, "Foo")// Ok
extern(C) void foo();
void main() {
pragma(mangle, "Bar")// Error
extern(C) void bar();
}
---
Any idea why?
See also:
https://issues.dlang.org/show_bug.cgi?id=15843
https://issues.dlang.org/show_bug.cgi?id=17638
https://issues.dlang.org/show_bug.cgi?id=19149
pragma mangle on extern(C) in function body
While it is perfectly ok to define an extern(C) function in a
function method, I can't seem to get pragma(mangle, "...") on it
to work.
---
pragma(mangle, "Foo")// Ok
extern(C) void foo();
void main() {
pragma(mangle, "Bar")// Error
extern(C) void bar();
}
---
Any idea why?
Re: Why does nobody seem to think that `null` is a serious problem in D?
On Saturday, 1 December 2018 at 20:41:53 UTC, Sebastiaan Koppe wrote: Since the compiler can prove which branch is taken, the analyse has to assume both are. *can't*
Re: Why does nobody seem to think that `null` is a serious problem in D?
On Saturday, 1 December 2018 at 19:02:54 UTC, H. S. Teoh wrote:
But that's precisely the problem. It's not always possible to
tell whether a variable has been initialized. E.g.:
int func(int x) {
int *p;
if (solveRiemannHypothesis()) {
p =
}
...
if (solveArtinsConjecture()) {
*p++;
}
return x;
}
If you are willing to loose some precision you can still analyse
this. Google abstract interpretation.
For instance, after the first if the value of p is ( || null).
Since the compiler can prove which branch is taken, the analyse
has to assume both are.
Inside the second if, p gets dereferenced, but since p is ( ||
null) - that is, it might be null - that is a compile time error.
The take away is that you don't need to know what code path will
be taken, you just combine both states.
Re: How do I use null in a struct?
On Saturday, 10 November 2018 at 19:42:47 UTC, Václav Kozák wrote: I'm making a Rest API with vibe.d and I have a struct User. Sometimes I need to return only a few of the fields. So for example: return User(1, null, "John", null, null, ...); If I do this, an error occurs: cannot implicitly convert expression null of type typeof(null) to ... Thanks. You can use Optional like drug said, or you can use the @optional attribute [1]. @optional will leave the field in its .init state, whereas with Optional its easier to detect the null state. [1] http://vibed.org/api/vibe.data.serialization/optional
Re: Need help with calling a list of functions
On Sunday, 4 November 2018 at 01:17:01 UTC, Luigi wrote: I need to call a function that can create a function from an array of functions and calls them in reverse order. I am learning D any help would be That sounds a lot like std.functional.compose
Re: Template/mixin ideas?
On Thursday, 4 October 2018 at 01:12:04 UTC, Chris Katko wrote: The mixin part wouldn't be slowed by strings, right? So the "slowness" is the invokation part which changes strings and forces GC allocations, I guess? Yep, that is right. What's the alternative to using strings... for strings? During the concatenation phase you'll use an Appender. Afterwards you retrieve the resulting string from the appender. It is very similar to a StringBuilder in other languages. See std.array.appender
Re: Template/mixin ideas?
On Wednesday, 3 October 2018 at 11:01:53 UTC, Chris Katko wrote:
I've got this simple task but I'm trying to perfect it as best
I can to learn something in the process.
I have Linux terminal ASCII codes for coloring terminal output.
string red(string) { /* ... */ }
"Hello world".red => "\033[31mHello World\033[0m"
which translates to "[red]Hello World[reset to normal text]".
I have to do some slight trickery so I can chain them. But it
all works fine. __The function is the same__ no matter what
kind of color, bold, etc attribute I want. The only difference
is the tag/prefix string.
So I have a table (or enum):
enum colors{
reset = "\033[0m",
red = "\033[31m",
bold = "\033[1m" //...
}
Absolute perfection would be some way to add a single line to
that enum (or table) and magically get a new function. I add
"blue" with its prefix code to the enum and immediately I can
do:
"hello world".blue
Add yellow = "\033..." and I can do:
"hello world".bold.yellow
It's an interesting problem. Right now, I made a generic
version that accepts the prefix code string directly called
"color()" and red() translates to a call to color with the red
string. blue() does the same. And so on. But it's still plenty
of boiler plate. I do that so I don't have 80+ functions all a
half-page long--which would be a nightmare to verify.
It's surely nothing mission critical. But I wonder if I can
distill this simple problem down further, I may be able to
learn some tricks for later problems.
Thanks.
A combination of static introspection with string mixins does the
trick:
---
enum colors {
reset = "\033[0m",
red = "\033[31m"
}
auto GenerateColorFuncs() {
string result;
static foreach(c; __traits(allMembers, colors))
result ~= "auto "~c~"(string str) { return colors."~c~" ~
str ~ colors.reset; }";
return result;
}
mixin(GenerateColorFuncs());
void main()
{
import std.stdio;
writeln("bla".red);
}
---
Although you might want to replace the string concatenation with
something more performant if used a lot.
Re: Template return type?
On Wednesday, 3 October 2018 at 10:01:02 UTC, Andrea Fontana wrote: On Wednesday, 3 October 2018 at 09:37:29 UTC, JN wrote: int i = returnDefault!int(); obviously works, but the point is I would like to skip the explicit type. See: https://forum.dlang.org/post/ufhibwmouxpivjylq...@forum.dlang.org See also: https://forum.dlang.org/post/qmmjiofwmzqzdsgmv...@forum.dlang.org
Re: vibe.d error
On Thursday, 27 September 2018 at 17:37:43 UTC, hridyansh thakur wrote: [snip] What version of dmd do you use?
Re: tupleof function parameters?
On Tuesday, 28 August 2018 at 06:11:35 UTC, Jon Degenhardt wrote: The goal is to write the argument list once and use it to create both the function and the Tuple alias. That way I could create a large number of these function / arglist tuple pairs with less brittleness. --Jon I would probably use a combination of std.traits.Parameters and std.traits.ParameterIdentifierTuple. Parameters returns a tuple of types and ParameterIdentifierTuple returns a tuple of strings. Maybe you'll need to implement a staticZip to interleave both tuples to get the result you want. (although I remember seeing one somewhere).
Re: UDA on double nested struct
On Monday, 20 August 2018 at 16:27:55 UTC, Basile B. wrote: Hello, it works fine here. Maybe there was another error that you removed when you have minimized the example. See https://run.dlang.io/is/ZrW7kI, that says that the example works since 2.068.2. Although that are are possibility that it was broken before a patch release, since only latest path of a minor release is tested on the site, in which case updating the compiler would fix the issue. Wow, that is really nice, running all compilers at once. Thanks for showing that. Anyway, I found out that the problem was that the `Hover` struct was named `hover` in my code. See https://run.dlang.io/is/3dLli6 In that case the inner hover takes precedence over the enum hover. Is that wanted behaviour? I would at minimum expect an ambiguity error.
UDA on double nested struct
Hey, I am trying to get UDAs from a doubly nested struct, to no
avail:
code
---
import std.traits : hasUDA;
enum hover;
struct Style {
struct Root {
auto margin = "10px";
auto backgroundColor = "white";
@hover struct Hover {
auto backgroundColor = "gray";
}
}
}
pragma(msg, hasUDA!(Style.Root.Hover, hover));
---
returns false. Bug or no? (Yes, I am generating css at compile
time.)
Putting it on Root or on Style works as intended;
Re: ?? How to subscribe to Multicast Broadcasts ??
On Monday, 13 August 2018 at 01:12:16 UTC, Joe wrote: Please Please Please Help, I am desperate! Many Thanks in Advance for your time & attention, -joe I implemented multicast support in vibe.d, I hope looking at the source can help you: https://github.com/vibe-d/vibe.d/blob/master/core/vibe/core/drivers/libevent2.d#L1129 Also, shouldn't both sending and receiving ports be the same? Where I use it I call addMembership and then canBroadcast on a vibed socket, and it has worked for me. It wouldn't be difficult to port that back to std.socket.
Re: Cannot make LDC use LTO when called via DUB
Neither dflags-dmd "-xxx" dflags-posix-dmd "-xxx" dflags-linux-dmd "-xxx" has any effect on my build (in dub.sdl). I didn't know dflags-* was a thing, and I can't find it in docs either. Maybe you are looking for dflags "..." platform="..."
Re: Is there any threadsafe queue?
On Wednesday, 13 September 2017 at 22:54:06 UTC, Seb wrote: https://code.dlang.org/packages/lock-free That package has a single-reader single-writer queue, exactly what the OP asked for.
Re: How to make http requests to unix socket?
On Friday, 11 August 2017 at 18:39:54 UTC, dvnguyen wrote:
How to make http requests to unix socket? For example, in
Docker engine api,
curl --unix-socket /var/run/docker.sock
http:/v1.24/containers/json
I made a pull request a year ago or so to have vibe-d's
requestHttp to support unix sockets. Call it like this
`requestHTTP("https+unix://%2Fvar%2Frun%2Fdocker.sock/containers/create`.
You will need to set some vibe-d tls things to accept the
connection.
Sönke just upgraded vibe-core/event-core to support it as well if
I remember it correctly (so you can also use vibe 8.x with
vibe-core).
As for endpoints which return streams (like
containers/"~id~"/logs?stdout=1=1=1), Docker
multiplexes stdout/stderr over http with chunked
transfer-encoding.
The protocol is a 8 byte Header + Frame. The last four bytes in
the Header is an uint32 representing the frame size. The first
byte is either 1 -> stdout or 2 -> stderr, which designates the
type of the stream in the following frame.
Re: Idiomatic way of writing nested loops?
On Monday, 17 July 2017 at 11:55:47 UTC, Anton Fediushin wrote: Thank you! I knew it is in the library! So, `parallel` will work just fine with this function, isn't it? Yes
Re: Idiomatic way of writing nested loops?
On Monday, 17 July 2017 at 11:07:35 UTC, Anton Fediushin wrote: Hello! What is the best way of rewriting this code in idiomatic D manner? https://dlang.org/phobos/std_algorithm_setops.html#.cartesianProduct
Re: Need simple sound
On Thursday, 6 July 2017 at 20:36:08 UTC, FoxyBrown wrote: Heres a better version that automatically generates a class wrapping the portaudio.dll. Need portaudio.di(possibly renamed to portaudio.d and imported). Still same problem as original though. While you are at it. Please also write compile time C preprocessor. (He said half jokingly.) I tried your example. Unfortunately my windows dev setup is so far beyond repair, I could not get it to run. I am sorry but I can't help you.
Re: Need simple sound
On Thursday, 6 July 2017 at 13:28:26 UTC, FoxyBrown wrote: On Wednesday, 5 July 2017 at 07:21:45 UTC, Sebastiaan Koppe wrote: Sure, see http://code.dlang.org/packages/portaudio So, after a bit of work I can get port audio to work but the callback never seems to be called(no audio, never hits bp). Shows all the devices and seems to run fine otherwise. Tried all the devices I I have. The default stream doesn't work either. The example I posted earlier did work on my Mac. I will try your example + dll loader on Windows later today. Nice loader btw.
Re: Need simple sound
On Thursday, 6 July 2017 at 10:47:53 UTC, FoxyBrown wrote: On Wednesday, 5 July 2017 at 07:21:45 UTC, Sebastiaan Koppe wrote: On Wednesday, 5 July 2017 at 05:34:37 UTC, FoxyBrown wrote: On Tuesday, 4 July 2017 at 20:37:44 UTC, Sebastiaan Koppe wrote: Portaudio is simple as well. And nice cross platform. are there any bindings? Sure, see http://code.dlang.org/packages/portaudio I can't seem to get this to work. Are there any windows dll's or libs that work that are not outdated? I have found dlls here https://github.com/spatialaudio/portaudio-binaries
Re: unittest-cov - results?
On Wednesday, 5 July 2017 at 19:01:06 UTC, Jonathan M Davis wrote: I ran into a bug in dub not all that long ago where the tests in the module with main in it weren't actually being run even though the other tests were. (which reminds me, I should verify that again and report it). - Jonathan M Davis Noticed it as well couple of months ago. I think dub just skips the mainSourceFile defined in the dub.sdl (default: source/app.d) to avoid having 2 mains. It is annoying especially for small projects where you would only have app.d. Especially if you don't have a clue what is going on.
Re: Need simple sound
On Wednesday, 5 July 2017 at 09:43:05 UTC, Martin Tschierschke
wrote:
On Wednesday, 5 July 2017 at 07:21:45 UTC, Sebastiaan Koppe
wrote:
On Wednesday, 5 July 2017 at 05:34:37 UTC, FoxyBrown wrote:
On Tuesday, 4 July 2017 at 20:37:44 UTC, Sebastiaan Koppe
wrote:
Portaudio is simple as well. And nice cross platform.
are there any bindings?
Sure, see http://code.dlang.org/packages/portaudio
Sorry, for that question but now, as I have several different
options -
all not 'overdocumented' - so what would be the shortest
possible D program waiting for input and playing a sound from a
file in parallel?
Something short like the single-file dub example...?
#!/usr/bin/env dub
/+ dub.sdl:
name "hello"
+/
void main() {
writef("Do you like the music?");
char[] answer;
answer = readln();
writef("This was your Answer: ", answer);
}
This one plays a wav file. Couldn't get dub to do single-file on
it. It kept giving linker errors. (Took example from
https://github.com/v--/portaudio/blob/master/examples/pa_test.d)
**dub.sdl
name "audio"
description "plays audio file"
authors "Sebastiaan Koppe"
dependency "portaudio" version="==1.0.0"
dependency "wave-d" version="~>1.0.6"
configuration "executable" {
mainSourceFile "audio.d"
targetType "executable"
}
**audio.d
import std.stdio;
import waved;
import deimos.portaudio;
import std.conv, std.stdio;
import std.algorithm : min;
struct Audio {
float* samples;
size_t frames;
size_t position;
}
extern(C) int callback(const(void)* inputBuffer, void*
outputBuffer,
size_t framesPerBuffer,
const(PaStreamCallbackTimeInfo)*
timeInfo,
PaStreamCallbackFlags statusFlags,
void *userData)
{
auto pout = cast(float*)outputBuffer;
Audio* audio = cast(Audio*)userData;
enum vol = 0.2f;
size_t frames = min(audio.frames - audio.position,
framesPerBuffer);
foreach(i; 0 .. frames)
*pout++ = vol * audio.samples[i + audio.position];
foreach(i; frames .. framesPerBuffer)
*pout++ = 0;
audio.position += framesPerBuffer;
return frames == framesPerBuffer ? paContinue : paComplete;
}
int main()
{
PaStream* stream;
PaError err;
Sound input = decodeWAV("my_wav_file.wav");
string answer;
auto audio = Audio(input.samples.ptr, input.samples.length);
if ((err = Pa_Initialize()) != paNoError) goto Lerror;
if ((err = Pa_OpenDefaultStream(,
0,
input.channels,
paFloat32,
cast(double)input.sampleRate,
paFramesPerBufferUnspecified,
,
))
!= paNoError) goto Lerror;
if ((err = Pa_StartStream(stream)) != paNoError) goto Lerror;
writef("Do you like the music?");
answer = readln();
writefln("This was your Answer: %s", answer);
if ((err = Pa_StopStream(stream)) != paNoError) goto Lerror;
if ((err = Pa_CloseStream(stream)) != paNoError) goto Lerror;
if ((err = Pa_Terminate()) != paNoError) goto Lerror;
return 0;
Lerror:
stderr.writefln("error %s", to!string(Pa_GetErrorText(err)));
return 1;
}
Re: Need simple sound
On Wednesday, 5 July 2017 at 05:34:37 UTC, FoxyBrown wrote: On Tuesday, 4 July 2017 at 20:37:44 UTC, Sebastiaan Koppe wrote: Portaudio is simple as well. And nice cross platform. are there any bindings? Sure, see http://code.dlang.org/packages/portaudio
Re: Need simple sound
On Monday, 3 July 2017 at 08:55:20 UTC, Martin Tschierschke wrote: Hello for a simple game I would like to add some very simple sound, not much different than the beeps of "PAC Man". Is there anything I can use for this? Portaudio is simple as well. And nice cross platform.
Re: Deprecated std.c.*.socket and missing replacement
On Tuesday, 27 June 2017 at 19:22:02 UTC, Steven Schveighoffer wrote: Just delete the duplicate symbol, and add public imports of the other module symbols. e.g.: public import core.sys.posix.netinet.in_: IP_ADD_MEMBERSHIP; -Steve Great. Will do.
Re: Deprecated std.c.*.socket and missing replacement
On Tuesday, 27 June 2017 at 17:58:29 UTC, Jonathan M Davis wrote: Why would you need to remove anything from Phobos? The enum in question is in a deprecated module. All that should need to happen is that the enum be added to the appropriate module in druntime, and then any code that uses it can import it from there. - Jonathan M Davis Except that the deprecated module (std.c.posix.socket) imports the module where I would like to add them (core.sys.posix.netinet.in_), resulting in duplicated symbols. Therefor they need to be removed.
Re: Deprecated std.c.*.socket and missing replacement
On Tuesday, 27 June 2017 at 11:16:17 UTC, Jonathan M Davis wrote: Create a PR to add it to druntime and/or define it in your own code. - Jonathan M Davis Creating a PR sounds reasonable. But I would have to create one PR to remove them from phobos and one PR to add them to druntime, right? (I need to remove them since the phobos socket modules import the druntime ones, create duplicates if not removed) I see that std.c.windows.winsock simply publicly imports core.sys.windows.winsock2, that looks like a good approach.
Deprecated std.c.*.socket and missing replacement
I am building a multicast application, and I am using the std.c.*.socket modules to provide the definition of the IP_ADD_MEMBERSHIP constant. These modules are marked as deprecated telling me to look in core.sys.posix.* instead. I grepped the complete sourcetree, but nowhere is the IP_ADD_MEMBERSHIP constant defined other than in the deprecated modules. What to do?
Re: Dub and unit-threaded import problem
On Saturday, 5 March 2016 at 15:05:50 UTC, Casey wrote:
{
"name": "unittest",
"preBuildCommands": [
"dub run unit-threaded -c gen_ut_main -- -f bin/ut.d"
],
"mainSourceFile": "bin/ut.d",
"excludedSourceFiles": ["source/app.d"],
"dependences": {
"unit-threaded": "~>0.6.3"
}
}
If dub is complaining about not finding bin/ut.d, You need a
"importPaths": ["bin"] in there. Dub by default only looks in the
source folder, and it cannot find `bin/ut.d` in `./source`. If
that is the case you also need to remove the `source` part from
the excludedSourceFiles.
Here is a config that works for me
{
"name": "unittest",
"preBuildCommands": ["dub run unit-threaded -c gen_ut_main --
-f bin/ut.d"],
"importPaths": ["bin"],
"mainSourceFile": "bin/ut.d",
"excludedSourceFiles": ["app.d"],
"dependencies": {
"unit-threaded": "~>0.6.3"
}
}
Re: Coverage
On Tuesday, 16 February 2016 at 12:35:38 UTC, Leandro Motta Barros wrote: You probably already though of it, but: can't you create a unittest that calls your code as many times as desired, passing different input each time? That is a viable option yes. I will probably end up doing it like that. I don't like it though. Since the input is pretty big, it would need to be kept in an external file. And I don't like my unittests reading files. Plus they aren't really unittests either. Oh well. Moving on.
Coverage
I currently run dmd's coverage on my unittests. But now I also want to execute my program with different inputs and then merge all that coverage info from each run. Any chance there is something for that?
Re: htod question
On Friday, 22 January 2016 at 01:04:50 UTC, Dibyendu Majumdar wrote: On Friday, 22 January 2016 at 01:03:09 UTC, Dibyendu Majumdar wrote: On Friday, 22 January 2016 at 00:52:59 UTC, W.J. wrote: Counter question: What's so bad about the D std library ? I am trying to create bindings for existing C library so I was trying to use htod for that. The library includes various C header files ... causing htod to fail Yeah, htod often requires preparing the files your trying to convert. Often removing macro's and the like. Its a manual process, and it can get dirty.
Re: Is this a feature?
On Thursday, 21 January 2016 at 14:39:43 UTC, Adam D. Ruppe wrote: On Thursday, 21 January 2016 at 14:35:09 UTC, Sebastiaan Koppe wrote: static if (!is(SomethingUndefined!moreUndefined[0] : UndefinedThing)) Yes, the is expression returns false for undefined things because they aren't types. The standard library uses this in a lot of places to test for undefined functions, like checking for features in ranges. (The is expression has been around a lot longer than __traits btw) Thanks. I reckoned as much. Can be handy in places. But I just spend some time figuring out that I was missing an import...
Is this a feature?
module undefined;
unittest
{
static if (!is(SomethingUndefined!moreUndefined[0] :
UndefinedThing))
{
pragma(msg,"This will compile just fine!");
}
}
Re: Reset all Members of a Aggregate Instance
On Thursday, 3 December 2015 at 21:13:59 UTC, Nordlöw wrote: Need to assert that not a function and mutability (std.traits.isMutable) Yeah you need to do that.
Re: Reset all Members of a Aggregate Instance
Haven't compiled but it should look something like this: foreach(member; __traits(allMembers, typeof(c))) __traits(getMember, c, member) = typeof(__traits(getMember, c, member)).init;
Re: vibe.d-example illustrating Dynamic Textual Web-Interface
On Tuesday, 1 December 2015 at 07:04:25 UTC, Sönke Ludwig wrote: Am 30.11.2015 um 11:08 schrieb Nordlöw: Does anybody have a similar vibe.d-project to be inspired from, in this regard? This would be more targeted to the web interface generator (vibe.web.web), which is not affected by the changes mentioned above, but the interface is pretty similar. For a very simple example, you can have a look at this: https://github.com/rejectedsoftware/vibe.d/tree/master/examples/web_ajax I have seen a lot of sites using this approach. I feel that once complexity increases (more dynamics, popups, real-time validation, spa) it runs into some maintenance issues. Let me elaborate. In the beginning all html is generated on the server. Then more features are added and slowly more html is generated/manipulated in the client. Now you have this split-brain were html is generated both on the server and the client, but both in different languages, with different template engines. To put it simply, it doesn't scale well. The solution would be to shift the generation of html to the client (for example see trello, digital ocean, etc.). The only issue there is that the first page load takes longer. This can be solved by rendering the first page on the server. With nodeJS this is easy since you can reuse the same code, with D this is a little harder.
Re: Can't understand how to do server response with vibed
On Sunday, 29 November 2015 at 07:37:56 UTC, Suliman wrote: On Saturday, 28 November 2015 at 23:21:21 UTC, Sebastiaan Koppe wrote: On Saturday, 28 November 2015 at 19:05:59 UTC, Suliman wrote: And also I can't understand difference between HTTPClientRequest and HTTPServerRequest If the application (vibe.d) makes a request, it is the client. If the request is made to your application, it is the server. In your case your angular app is the client, and your vibe.d app is the server. Therefor, HTTPServer(Request|Response). Could you explain me about: HTTPServerRequest and HTTPRequest. I can't understand difference. No idea. Probably HTTPRequest provides common functionality for both HTTPServerRequest and HTTPClientRequest. Just guessing.
Re: vibe.d-example illustrating Dynamic Textual Web-Interface
On Monday, 30 November 2015 at 10:08:17 UTC, Nordlöw wrote: Can somebody please show a enlightening example of, so called, "revamp of the REST interface generator" added to release 0.7.26 at: http://vibed.org/blog/posts/vibe-release-0.7.26 I want to use vibe.d to add a modern dynamic web-interface to my knowledge graph I'm currently developing. More specifically I would like an interface that makes rich use of dynamic HTML. When the user changes the contents of a search/command-line text-field the client logic shall on the fly (after a certain delay) lookup related information with vibe.d-server and present the user with relevant hits or completions in a another part of page (HTML div-block). Does anybody have a similar vibe.d-project to be inspired from, in this regard? I have written a mpd (Music Player Daemon) client in D and just finished the web app (bar a couple of features). All of the rendering is done on the client and only json data is transmitted between server and web app. Just finished the WebSocket part so if anybody changes the music/volume/playlist, all clients update the interface. The code could use a cleanup/refactoring but everything is working. The D parts of interest are the MpdApiInterface1 and MpdApi1 classes in source/app.d For the JS parts you can start with source/index.js, but its full of ES6 classes and react code. So that might not be your cup of tea. In index.js there are mainly React Classes (basically html renderers) and React Container Classes (basically code handling input changes). In the source/actions folder there are some js files that call the server and modify state (volume/song). In the source/stores folder, some js files that only retrieve data. The js architecture if influenced by react/flux/facebook's, but I am toying with it to see what fits for me. Specifically I rely a lot on RxJS for the observables. For the project I decided to put js and d files in the same folders. That might not have been a good idea. Also dub has some issues with one of the D dependencies that I haven't updated in months. Code can be found here: https://bitbucket.org/skoppe/mpc/src
Re: vibe.d-example illustrating Dynamic Textual Web-Interface
On Monday, 30 November 2015 at 20:23:48 UTC, David DeWitt wrote: Have you looked at Redux and Webpack? I am working on a Redux example and we have switched to Webpack and Redux at work and it is nice. I know about both yes. Webpack would probably beat browserify, but I haven't gotten the time to migrate myself. Their hot code reloading looks good though. Isn't redux the client side for GraphQL? I followed it a bit but it being so fresh, decided to wait. A GraphQL interface generator for vibe.d would be nice.
