Re: dlang.org/Learn "hello_world".sort.chain ...

[tony via Digitalmars-d-learn]

On Tuesday, 26 December 2023 at 11:19:29 UTC, Sergey wrote:


Use typeid, instead of typeof


Thanks!

Got quite a type but I will worry about that later: 
std.range.SortedRange!(Result, "a < b").SortedRange

TDPL book and __traits(compiles...) snippet

[Tony via Digitalmars-d-learn]

In section 6.2 of The D Programming Language it talks about how 
the compiler will try and tell if you are going to use a null 
reference. It gives this code snippet below to demonstrate that. 
But with DMD v2.096.1-dirty I am getting that the compiler thinks 
the code is OK. With a "!" the assert fails.


class A { int x; }
A a;
assert(!__traits(compiles, a.x = 5));

Re: Error: Outside Unicode code space

[Tony via Digitalmars-d-learn]

On Friday, 9 July 2021 at 03:32:31 UTC, Adam D Ruppe wrote:

On Friday, 9 July 2021 at 03:09:52 UTC, Tony wrote:
The editor I am using (Code::Blocks) displays the characters 
just fine. So it seems that the error message should be 
"Error: Outside the ASCII code space".


D supports stuff outside the ASCII code space just fine.

Are you sure the file is saved as utf 8? if it is something 
like Windows 1252 it can still often be displayed but dmd won't 
know what to make of it.


When I checked "Settings->Editor...->Encoding Settings" it was 
set to WINDOWS-1252. Changing it to UTF-8 fixed the issue. Thanks!

Error: Outside Unicode code space

[Tony via Digitalmars-d-learn]

I copied some text from a web page into a comment and I get the 
error

"Error: Outside Unicode code space".

This appears to be an incorrect error message. It is upset about 
double quotes that lean forward or backwards, and apostrophes 
that lean backwards. And dashes that aren't the keyboard dash 
character.


The editor I am using (Code::Blocks) displays the characters just 
fine. So it seems that the error message should be "Error: 
Outside the ASCII code space".

Re: ChromeOS and DLang

[Tony via Digitalmars-d-learn]

On Thursday, 27 May 2021 at 19:39:15 UTC, Ozan Sueel wrote:

Hi
I think about writing apps vor ChromeOS, but before running in 
a death end, I ask by myself, is D a good choice for this 
approach?


Any experience with this new upcoming operating system?

New and upcoming? ChromeOS was first released 10 years ago. Are 
they adding something different to it?

Re: ugly and/or useless features in the language.

[Tony via Digitalmars-d-learn]

On Saturday, 15 May 2021 at 21:15:01 UTC, Ola Fosheim Grostad 
wrote:

On Saturday, 15 May 2021 at 14:31:08 UTC, Alain De Vos wrote:




In general it is better to have fewer features and instead 
improve metaprogramming so that missing features can be done in 
a library.




Why is metaprogramming added features better than the same 
features added in the language? One is standard between entities, 
the other is not.

Re: DConf talk : Exceptions will disappear in the future?

[Tony via Digitalmars-d-learn]

On Tuesday, 5 January 2021 at 18:42:42 UTC, Marvin wrote:

On Monday, 4 January 2021 at 15:39:50 UTC, ludo456 wrote:
Listening to the first visioconf of the Dconf 2020, titled 
Destroy All Memory Corruption, 
(https://www.youtube.com/watch?v=XQHAIglE9CU) Walter talks 
about not using exceptions any more in the future. He says 
something like "this is where languages are going" [towards no 
using exceptions any more].


Can someone point me to an article or more explanations about 
that?



if Exceptions disappear in the future in Dlang, I will download 
the last version that support exceptions and never update.


I have a similar feeling. Exceptions were a great addition to 
programming languages in my opinion.

Re: Pro programmer

[Tony via Digitalmars-d-learn]

On Sunday, 25 August 2019 at 21:30:10 UTC, GreatSam4sure wrote:
I am wondering as to what is the starting point of being a pro 
programmer. If I want to be a pro programmer what language must 
I start with?


Most pro programmer I have heard of are all C and C++ Guru. 
Most of the best guys on this D forum falls into that category.


I really want to know programming to the core not just tied to 
a language or just at the level of drag and drop or use a 
framework or library.




I will appreciate your help in this matter. I am ready to put 
in hard work. I ready know a little of java, actionscrip 3.0, 
kotlin, D but at the surface level but can use them to write 
app.


But I am concern with matter like how can I write a GUI toolkit 
from the ground up.


When you say "pro programmer" are you referring to someone who 
programs for a living for a company, or a "top notch/very good 
programmer" ?

Re: Help me decide D or C

[Tony via Digitalmars-d-learn]

On Wednesday, 31 July 2019 at 22:30:52 UTC, Alexandre wrote:


My goals:

1) Improve as a programmer
2) Have fun doing programs

That's it basically. I am planning to study all "free" time I 
have. I am doing basically this since last year.


Are you only considering D and C or just mentioning them in this 
forum? The interpreted dynamically-typed languages like Python 
are considered easier to use and have the largest amount of 
functionality in their libraries.


If it is just down to D or C, then definitely D. C would be at or 
near the bottom in terms of a language to have fun doing general 
programming and learning.

Re: Singleton in Action?

[Tony via Digitalmars-d-learn]

On Saturday, 2 February 2019 at 16:56:45 UTC, Ron Tarrant wrote:


So, my big question is, do I instantiate like this:

DSingleton singleton = new DSingleton;

Or like this:

DSingleton singleton = singleton.get();

And subsequent calls would be...? The same? Using get() only?


This seems to be a case where D's definition of "private" can 
cause confusion versus examples from other languages with private 
as "access only inside the class". In other languages


DSingleton singleton = new DSingleton;

would never compile (the desired behavior), since the constructor 
is private.


But D allows it in some cases due to "private to class OR 
module". If DSingleton is in the same module, as for example in a 
small test program with DSingleton and main() in the same file, 
then it compiles.


So I think your code is fine, it's just that it can be 
circumvented - the private constructor can be called - if 
DSingledton and the instantiating code are in the same module.

Re: Why does nobody seem to think that `null` is a serious problem in D?

[Tony via Digitalmars-d-learn]

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.:


To me, the possibility of a "false positive" doesn't preclude the 
use of a warning unless that possibility is large. Besides using 
a compiler option or pragma to get rid of it, the warning also 
goes away if you assign NULL or (X *) 0. Surprisingly, clang (gcc 
6.3 does not give the warning) is not smart enough to then issue 
a "possibly dereferencing null pointer" warning.




Therefore, leaving it up to the compiler to detect 
uninitialized variables is unreliable, and therefore any code 
that depends on this cannot be trusted. Code like the above 
could be exploited by a sufficiently sophisticated hack to make 
the uninitialized value of p coincide with something that will 
open a security hole, and the compiler would not be able to 
reliably warn the programmer of this problem.


I don't know that "leaving it up to the compiler" is a correct 
characterization. I don't see the programmer doing anything 
different with the warning capability in the compiler than if it 
wasn't there. In either case, the programmer will attempt to 
supply values to all the variables they have declared and are 
intending to use, and in the correct order.

Re: Why does nobody seem to think that `null` is a serious problem in D?

[Tony via Digitalmars-d-learn]

On Saturday, 1 December 2018 at 11:16:49 UTC, Dukc wrote:
This is great when it works, but the problem is that it would 
be gargantuan effort -and compile time sink- to make it work 
perfectly. When it's just about if-else if chains, switches or 
boolean logic as in the example, the analysis won't be too 
complicated. But swap those booleans out for a string, and make 
the conditions to test whether it's a phone number, and whether 
it satisfies some predicate implemented in a foreign language, 
and you'll see where the problem is.


I think he is just talking about the compiler or static analyzer 
seeing if a variable has been given a value before it is used, 
not if it was given a valid value.

Re: Why does nobody seem to think that `null` is a serious problem in D?

[Tony via Digitalmars-d-learn]

isocpp.org just had a link to a blog post where someone makes a 
case for uninitialized variables in C++ being an advantage in 
that you can potentially get a warning regarding use of an 
uninitialized variable that points out an error in your code.


https://akrzemi1.wordpress.com/2018/11/22/treating-symptoms-instead-of-the-cause/

Re: D is supposed to compile fast.

[Tony via Digitalmars-d-learn]

On Sunday, 25 November 2018 at 22:00:21 UTC, Chris Katko wrote:

On Saturday, 24 November 2018 at 20:44:57 UTC, welkam wrote:

On Friday, 23 November 2018 at 08:57:57 UTC, Chris Katko wrote:

D is supposed to compile fast.


You didnt read the fine print. It compiles simple code fast. 
Also compilation is separate step from linking and your 
program might spend half of "compilation" time in link phase.


Wait wait wait wait wait.

So 1) I have to compile manually, then link. Except that also 
runs the files every time even if they're up-to-date. Is that 
normal behavior for C/C++?


"runs the files every time"?  If that means "compiles the files 
every time", then no. D  works exactly like C/C++ - you only need 
to compile-to-object-code source files in the project that have 
changed since the last time they were compiled.

D Language 2.1

[Tony via Digitalmars-d-learn]

From std.compiler.D_major and std.compiler.D_minor I see that my 
D language version is at 2.0 . But the version of gdc front-end I 
am using (via Debian default gdc package as of a few months ago) 
from std.compiler.version_major and std.compiler.version_minor is 
at 2.68 . That is a lot of bug fixes, with 0 changes to the 
language.


Actually, I realize that changes to the language are being 
reflected in compiler versions, not language versions. Just 
wondering why it was decided not to version the language (2.1, 
2.2, etc.)

version(StdDoc)

[Tony via Digitalmars-d-learn]

In std.compiler there is this code:

/// Which vendor produced this compiler.
version(StdDdoc)  Vendor vendor;
else version(DigitalMars) Vendor vendor = Vendor.digitalMars;
else version(GNU) Vendor vendor = Vendor.gnu;
else version(LDC) Vendor vendor = Vendor.llvm;
else version(D_NET)   Vendor vendor = Vendor.dotNET;
else version(SDC) Vendor vendor = Vendor.sdc;
else  Vendor vendor = Vendor.unknown;

What is the situation in which the identifier StdDoc is set?

Re: Who can stop it ? Help me,thank you.

[Tony via Digitalmars-d-learn]

On Wednesday, 17 October 2018 at 14:06:49 UTC, FrankLike wrote:


Where can get the new dmd or ldc2 that's no 'Trojan horse 
virus' ?


https://dlang.org/download.html

Re: Why is it hard to make Qt bindings?

[Tony via Digitalmars-d-learn]

On Thursday, 5 July 2018 at 12:52:49 UTC, Steven Schveighoffer 
wrote:

On 7/5/18 4:42 AM, drug wrote:
There were several attempts to make Qt binding for dlang, but 
either they has failed or has been stalled. It would be nice 
to collect that experience. Considering 2.081 supports C++ 
special member (not all but majority) isn't it time to make 
another attempt or the problem is more complex?

Could you publish your experience in making Qt bindings here?


I'm not a Qt user, but doesn't Qt require a special 
pre-compiler, or even use the preprocessor in a way that is 
difficult to duplicate in D?


Qt does have it's own pre-processor, but CopperSpice, a fork of 
Qt does not require that.


http://www.copperspice.com/

Re: Passing directory as compiler argument not finding file

[Tony via Digitalmars-d-learn]

On Friday, 13 April 2018 at 12:46:32 UTC, Cym13 wrote:

On Friday, 13 April 2018 at 01:27:06 UTC, Tony wrote:
I think that the typical model (at least in other languages) 
is to only compile one D source file at a time. Compile the 
b.d file with the -c option to create an object file. Then put 
the object file in a library file (either static (easier) or 
dynamic). Then you can use the -L compiler option to specify 
the directory of the library and the -l  compiler option to 
specify the library (library name is shortened - libb.a 
referenced as -lb).


Regardless of whether that would work or not this is the 
opposite of what's recommended in D. D compilers expect you to 
compile everything at once, or at least by module. That's where 
it works best when it comes to optimizations etc.


What does "or at least by module" mean? Is it possible to have a 
module that is made up of more than one source file?


What information does a D compiler get when you stick a.d and b.d 
on the command line that it doesn't get if you compile a.d and 
import b.d ?

Re: Passing directory as compiler argument not finding file

[Tony via Digitalmars-d-learn]

On Thursday, 12 April 2018 at 07:48:28 UTC, Jamie wrote:
 Really, it's more like:


A/
 a.d
module A.a;
import std.stdio;
import B.b;
void main()
{
writeln(f(4));
}
B/
 b.d
module B.b;
size_t f(size_t input)
{
return input * 2;
}

And in A/ I'm compiling
dmd -ofoutput a.d ../B/b.d

and instead I was thinking I could compile with
dmd -ofoutput a.d -I../B b.d

and would get the same result. The former works, the latter 
does not. Is there something like this that I can use or do I 
have to pass all the files with the direct path to them? Thanks


I think that the typical model (at least in other languages) is 
to only compile one D source file at a time. Compile the b.d file 
with the -c option to create an object file. Then put the object 
file in a library file (either static (easier) or dynamic). Then 
you can use the -L compiler option to specify the directory of 
the library and the -l  compiler option to specify the library 
(library name is shortened - libb.a referenced as -lb).

Re: Passing directory as compiler argument not finding file

[Tony via Digitalmars-d-learn]

On Thursday, 12 April 2018 at 05:39:21 UTC, Jamie wrote:


Am I using the -I compiler option incorrectly?


I believe so. I think it is for finding import files, not the 
files you are compiling.


-
-I=directory
 Look for imports also in directory

Re: Packages and module import

[Tony via Digitalmars-d-learn]

On Monday, 19 March 2018 at 17:29:10 UTC, Russel Winder wrote:
I had assumed that a directory of modules was a package. So for 
example:


[...]


On Monday, 19 March 2018 at 17:29:10 UTC, Russel Winder wrote:

To my amateur eyes, first command-line build looks like a linking 
of object files into a .so. The second command-line build looks 
like compilation is taking place. Seems like the command-line 
used to compile the library is missing.

Re: how to make private class member private

[Tony via Digitalmars-d-learn]

On Sunday, 18 March 2018 at 18:04:13 UTC, Tony wrote:

On Tuesday, 13 March 2018 at 06:03:11 UTC, Mike Parker wrote:



D is not C++, C#, or Java. C++ uses friend to get around the 
issue. Java has no solution. I don't know about C#.




Java has four protection levels. If you don't explicitly 
specify [private, protected, public] the protection level is 
implicitly "package-private". That means that any class in the 
same package can access that attribute. I believe that Java 
packages are identical to D packages.


https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/accessibility-levels

C# has 6 accessibility levels:

public - Access is not restricted.
protected - Access is limited to the containing class or types 
derived from the containing class.

private - Access is limited to the containing type.
internal - Access is limited to the current assembly.
protected internal - Access is limited to the current assembly or 
types derived from the containing class.
private protected - Access is limited to the containing class or 
types derived from the containing class within the current 
assembly. Available since C# 7.2.


What is a C# Assembly? Someone says on a forum:
"An assembly is a "unit of deployment" for .NET, almost always a 
.exe or .dll.

In C# terms, it's basically a single C# project."

And also refers to
https://social.msdn.microsoft.com/Forums/en-US/088ce8ed-ef9b-4dea-88b3-ca016885e26d/what-is-an-assembly-in-terms-of-c?forum=csharplanguage
which says:
"Assemblies are the building blocks of .NET Framework 
applications; they form the fundamental unit of deployment, 
version control, reuse, activation scoping, and security 
permissions. An assembly is a collection of types and resources 
that are built to work together and form a logical unit of 
functionality. An assembly provides the common language runtime 
with the information it needs to be aware of type 
implementations. To the runtime, a type does not exist outside 
the context of an assembly."

Re: how to make private class member private

[Tony via Digitalmars-d-learn]

On Sunday, 18 March 2018 at 18:32:42 UTC, Jonathan M Davis wrote:



They're similar, but there are differences. For instance, you 
can do package(a) in D in order to do something like put the 
stuff in a.b.c in package a rather than a.b.


Is there a known situation where it makes sense to put module c 
in directory/package b - rather than directory/package a, and 
then tell the D compiler to treat it like it was in 
directory/package a?

Re: how to make private class member private

[Tony via Digitalmars-d-learn]

On Tuesday, 13 March 2018 at 06:03:11 UTC, Mike Parker wrote:



D is not C++, C#, or Java. C++ uses friend to get around the 
issue. Java has no solution. I don't know about C#.




Java has four protection levels. If you don't explicitly specify 
[private, protected, public] the protection level is implicitly 
"package-private". That means that any class in the same package 
can access that attribute. I believe that Java packages are 
identical to D packages.

Re: How to simplify nested ifs

[Tony via Digitalmars-d-learn]

On Tuesday, 13 March 2018 at 12:23:06 UTC, Ozan Süel wrote:


if (source?pool?repository?directory?users) // do something



That type of chain is sometimes referred to as a "train wreck" 
(see Law of Demeter).


If this is a common lookup it could be:

if (source && source.GotSomeUsers() )

Re: Do forum posts use any markup language?

[Tony via Digitalmars-d-learn]

On Saturday, 10 March 2018 at 18:02:48 UTC, Bogdan wrote:
I'd like to distinguish between regular text and code, maybe 
have quotes, etc.


A poster has come up with a standard way to delineate code and 
also show if multiple files are involved (along with an 
"extraction to files" program):


https://forum.dlang.org/thread/ndgdqraxjkuvfsjhe...@forum.dlang.org

This method now works at https://run.dlang.io

Re: std.traits.isBoolean

[Tony via Digitalmars-d-learn]

On Monday, 19 February 2018 at 17:22:04 UTC, Nathan S. wrote:

On Monday, 19 February 2018 at 15:12:15 UTC, Tony wrote:
But, assuming there is a use case for it, what if you want to 
restrict to a type that is either boolean, or a struct/class 
that can substitute for boolean - how do you do that without 
using the "private" BooleanTypeOf thing?



In that case you can just write `is(T : bool)`.


Thanks.

Assuming it would substitute, that should probably be used on 
this page in place of BooleanTypeOf since BooleanTypeOf is not 
supposed to be public:


https://dlang.org/library/std/traits/is_boolean.html

"enum isBoolean(T) = is(BooleanTypeOf!T) && !isAggregateType!T;"

Re: std.traits.isBoolean

[Tony via Digitalmars-d-learn]

On Monday, 19 February 2018 at 13:47:15 UTC, Basile B. wrote:



Indeed but Phobos maintainers don't want the ...TypeOf family 
to be documented.

(https://github.com/dlang/phobos/pull/5747)


Ok, thanks.

But, assuming there is a use case for it, what if you want to 
restrict to a type that is either boolean, or a struct/class that 
can substitute for boolean - how do you do that without using the 
"private" TypeOfBoolean thing?

Re: std.traits.isBoolean

[Tony via Digitalmars-d-learn]

On Sunday, 18 February 2018 at 15:12:50 UTC, Mike Parker wrote:


Generally, no. But with alias this, it can be:

=
import std.traits : BooleanTypeOf;
import std.stdio : writeln;

struct NoBool {
int x;
}

struct AliasThisBool {
bool b;
alias b this;
}

void main()
{
static if(is(BooleanTypeOf!NoBool)) writeln("NoBool");
static if(is(BooleanTypeOf!AliasThisBool)) 
writeln("AliasThisBool");

}


Thanks!

It doesn't appear that BooleanTypeof is documented on dlang.org 
(outside of it's placement on the isBooleanType page). At least 
it isn't coming up in a "BooleanTypeOf site:dlang.org" search and 
not on the traits page:


https://dlang.org/library/std/traits.html

std.traits.isBoolean

[Tony via Digitalmars-d-learn]

At
https://dlang.org/library/std/traits/is_boolean.html

it has:


enum isBoolean(T) = is(BooleanTypeOf!T) && !isAggregateType!T;

per:
https://dlang.org/library/std/traits/is_aggregate_type.html

isAggregateType is true for [struct, union, class, interface].

So BooleanTypeOf!T is true for structs, unions, classes and 
interfaces? And if yes, why is that so?

Re: std.zip size limit of 2 GB?

[Tony via Digitalmars-d-learn]

On Thursday, 15 February 2018 at 18:49:55 UTC, Steven 
Schveighoffer wrote:




I think it's inherent in the zlib API. I haven't used all of 
the library, but the portion I did use (using zstream) uses 
uint for buffer sizes.




Wouldn't using a uint for buffer size give a size limit of 
greater than 4GB? Seems like an int is in the mix somewhere.

Wiki spam

[Tony via Digitalmars-d-learn]

Don't know if there is a better place to report this, but the 
wiki attracted a spammer:


https://wiki.dlang.org/The_Search_Of_Charter_Yacht_Designer

https://wiki.dlang.org/User:MichelMeudell

Re: String Type Usage. String vs DString vs WString

[Tony via Digitalmars-d-learn]

On Monday, 15 January 2018 at 02:09:25 UTC, rikki cattermole 
wrote:




Unicode has three main variants, UTF-8, UTF-16 and UTF-32.
The size of a code point is 1, 2 or 4 bytes.


I think to be technically correct, 1 (UTF-8), 2 (UTF-16) or 4 
(UTF-32) bytes are referred to as "code units" and the size of a 
code point varies in UTF-8 and UTF-16.

Re: Rvalue references

[Tony via Digitalmars-d-learn]

On Sunday, 14 January 2018 at 00:55:27 UTC, Jonathan M Davis 
wrote:



[...]


It the simplest case, it means that the compiler does a bitwise 
copy rather than a deep copy, but in other cases, it means that 
the compiler is able to use the object in-place rather than 
creating a deep copy that it places elsewhere. If you want to 
know more on the topic, you can always look into C++ move 
constructors. They were added so that C++ could avoid a lot of 
unnecessary copies. D took the approach of requiring that 
structs be moveable (e.g. it's undefined behavior to have a 
struct contain a pointer to itself), which simplifies things 
considerably.


[...]

Thanks!

Re: Rvalue references

[Tony via Digitalmars-d-learn]

On Monday, 8 January 2018 at 23:31:27 UTC, Jonathan M Davis wrote:



auto foo(T)(auto ref T t)
{
return t;
}

foo(42);

will result in foo being instantiated as

int foo(int t)
{
return t;
}

whereas

int i;
foo(i);

will result in foo being instantiated as

int foo(ref int t)
{
return t;
}

So, by using auto ref, a function can accept both lvalues and 
rvalues. And in D, rvalues get moved, not copied.


What does it mean to "move" a variable/value instead of copying 
it?


Was "auto ref" created for anything besides structs?

DUB and lib curl (-lcurl)

[Tony via Digitalmars-d-learn]

I am on Ubuntu 16.04. I was looking at Getting Started with DUB:
http://code.dlang.org/getting_started

I did the "dub init myproject" and it worked fine. Then I added 
dependency:


' dependency "dub" version="~>1.3.0" '

as shown in the next step. This got an error:
-
dub build
Fetching dub 1.3.0 (getting selected version)...
Performing "debug" build using dmd for x86_64.
dub 1.3.0: building configuration "library"...
../../../.dub/packages/dub-1.3.0/dub/source/dub/internal/sdlang/token.d(26,2): 
Deprecation: struct core.time.FracSec is deprecated - FracSec has been 
deprecated in favor of just using Duration for the sake of simplicity
../../../.dub/packages/dub-1.3.0/dub/source/dub/internal/sdlang/token.d(26,2): 
Deprecation: struct core.time.FracSec is deprecated - FracSec has been 
deprecated in favor of just using Duration for the sake of simplicity
myproject ~master: building configuration "application"...
Linking...
/usr/bin/ld: cannot find -lcurl
collect2: error: ld returned 1 exit status
Error: linker exited with status 1
dmd failed with exit code 1.
-

I am wondering if the tutorial should caution that "you need to 
have lib curl already on your system", or if I have a bad DUB 
install (lib curl should have been installed with DUB).

Re: Error trying to build dlang.org

[Tony via Digitalmars-d-learn]

On Thursday, 4 January 2018 at 02:20:32 UTC, Seb wrote:

On Thursday, 4 January 2018 at 01:50:47 UTC, Tony wrote:

Following the instructions here on Ubuntu 16.04:

https://github.com/dlang/dlang.org/blob/master/CONTRIBUTING.md

I did the command

make -f posix.mak html

but it failed to successfully complete:
---
make[1]: Leaving directory '/home/user/dlang/dmd/src'
../dmd/generated//release//dmd -c -o- 
-Df/home/user/dlang/dlang.org/web/spec/spec.html macros.ddoc 
html.ddoc dlang.org.ddoc doc.ddoc .generated/2.078.0.ddoc  
.generated/dblog_latest.ddoc .generated/twid_latest.ddoc 
spec/spec.ddoc spec/spec.dd

make: ../dmd/generated//release//dmd: Command not found
posix.mak:466: recipe for target 
'/home/user/dlang/dlang.org/web/spec/spec.html' failed
make: *** [/home/user/dlang/dlang.org/web/spec/spec.html] 
Error 127


1) Did you clone the `dmd` repository yourself?

yes


2) Is ../dmd existent?
Try nuking ../dmd and doing a fresh clone of ../dmd

I forgot to  check, but I deleted the dlang.org directory and 
tried again starting from git clone and this time it appears to 
have worked. Guess I should have tried that first before posting.

Error trying to build dlang.org

[Tony via Digitalmars-d-learn]

Following the instructions here on Ubuntu 16.04:

https://github.com/dlang/dlang.org/blob/master/CONTRIBUTING.md

I did the command

make -f posix.mak html

but it failed to successfully complete:
---
make[1]: Leaving directory '/home/user/dlang/dmd/src'
../dmd/generated//release//dmd -c -o- 
-Df/home/user/dlang/dlang.org/web/spec/spec.html macros.ddoc 
html.ddoc dlang.org.ddoc doc.ddoc .generated/2.078.0.ddoc  
.generated/dblog_latest.ddoc .generated/twid_latest.ddoc 
spec/spec.ddoc spec/spec.dd

make: ../dmd/generated//release//dmd: Command not found
posix.mak:466: recipe for target 
'/home/user/dlang/dlang.org/web/spec/spec.html' failed
make: *** [/home/user/dlang/dlang.org/web/spec/spec.html] Error 
127

Re: How to use the -I command line switch?

[Tony via Digitalmars-d-learn]

On Wednesday, 3 January 2018 at 12:21:28 UTC, tipdbmp wrote:

// C:\libs\my_module.d
module my_module;
void foo() {}

// main.d
module main;
import my_module;

void main() {
foo();
}

Running dmd with:
dmd -IC:\libs main.d my_module.d

I get:
Error: module my_module is in file 'my_module.d' which 
cannot be read

import path[0] = C:\libs
import path[1] = 
path\to\dmd\D\dmd2\windows\bin\..\..\src\phobos
import path[2] = 
path\to\dmd\D\dmd2\windows\bin\..\..\src\druntime\import


As has already been mentioned, the -I is not used for 
command-line files. Just compiling (-c option) shows that the -I 
is enough for DMD to find the import file:


dmd -c main.d -Ic:\libs

successfully compiles main.d into main.obj

To do a full compile and link of main without compiling 
my_module.d each time:


C:\libs>dmd -lib -ofmy_module.lib my_module.d

creates "my_module.lib". Then use it to link with in main.d 
compile/link:


C:\code\d\forum>dmd main.d -Ic:\libs -Llib c:\libs\my_module
OPTLINK (R) for Win32  Release 8.00.17
Copyright (C) Digital Mars 1989-2013  All rights reserved.
http://www.digitalmars.com/ctg/optlink.html
OPTLINK : Warning 9: Unknown Option : NOILIB


main.exe is created even though there is a mysterious warning.

Re: How to use the -I command line switch?

[Tony via Digitalmars-d-learn]

On Wednesday, 3 January 2018 at 18:35:21 UTC, Ali Çehreli wrote:

On 01/03/2018 09:10 AM, tipdbmp wrote:

dmd main.d C:\libs\my_module.d

That does not use the -I switch.

It compiles if I specify the full path to my_module.d:
     dmd -IC:\libs main.d C:\libs\my_module.d

I don't understand the error message though.



-I is for import directives only. imports are needed to compile 
the importing module. All other modules still need to be 
compiled themselves and added to the program either as 
individual .o files or as libraries (e.g. .a, .lib, etc.).


The method you've shown is a shorthand for "compile each to .o 
and add each to the program."


Working as expected... :)

What about the error message? If -I is only for DMD finding 
"import ..." files, and not files on the command line, why does 
DMD list what was in the -I "where to look for import directives" 
when saying that it can't find a command-line file? It says that 
it can't locate my_module.d and then lists the directory that 
my_module.d is in.

Re: Slices and Dynamic Arrays

[Tony via Digitalmars-d-learn]

On Monday, 1 January 2018 at 02:10:14 UTC, Jonathan M Davis wrote:



The DLang Tour should probably be fixed to use the term dynamic 
array though.


Or embrace both terms but take care that it is clear that they 
are synonyms and one may be preferred depending on context. As a 
beginner, I had some confusion seeing both terms used.


There is dual terminology in use outside of dlang.org. The book 
Programming In D says:


Slice: Another name for dynamic array.

When I write slice I will specifically mean a slice; and when I 
write array, I will mean either a slice or a fixed-length array, 
with no distinction.


Slices

Slices are the same feature as dynamic arrays. They are called 
dynamic arrays for being used like arrays, and are called slices 
for providing access to portions of other arrays. They allow 
using those portions as if they are separate arrays.

---

Re: How do you safely deal with range.front?

[Tony via Digitalmars-d-learn]

On Sunday, 31 December 2017 at 13:14:10 UTC, aliak wrote:

On Sunday, 31 December 2017 at 01:03:17 UTC, Tony wrote:
For me, front() should throw a pre-defined exception when 
called on an empty range in order to eliminate undefined 
behavior. It does take some time to make a check, but D does 
array bounds checking by default. Ideally the front() check 
could be turned off somehow ("-boundschecks=off") by the user 
for those who want maximum speed, but I guess there is no way 
to do that when using pre-compiled functions in a library.


That sounds like a good idea. Wouldn't the same apply to array 
bounds checking for precompiled functions though?


Yeah, seems like the standard library must be doing one or the 
other (bounds checking array indexes or not bounds checking them) 
all the time, depending on how it was compiled.


Also, is going out of array bounds well-defined behavior in D 
even with bounds check off?


I'm no expert, but I can't think of how it could be.


And any links to docs on UB in D?


This thread was the first time I have heard it used with regard 
to D.

Re: Slices and Dynamic Arrays

[Tony via Digitalmars-d-learn]

On Sunday, 31 December 2017 at 14:24:40 UTC, Jonathan M Davis 
wrote:




The D Slices article does an excellent job of explaining all of 
this. It's just that it calls the GC-allocated memory buffer 
the dynamic array instead of calling T[] the dynamic array like 
the language and spec do. Regardless, all non-null dynamic 
arrays are slices of memory.


The DLang Tour also uses the term slice to refer to T[].

"The type of arr is int[], which is also called a slice."

"A slice consists of two members - a pointer to the starting 
element and the length of the slice:"

Re: Slices and Dynamic Arrays

[Tony via Digitalmars-d-learn]

On Sunday, 31 December 2017 at 04:20:28 UTC, codephantom wrote:

On Sunday, 31 December 2017 at 03:57:17 UTC, Tony wrote:
On Sunday, 31 December 2017 at 03:08:05 UTC, Ivan Trombley 
wrote:

double[] D = [3.14159];

Can you guess what D is?  :D


It took me a while but I finally came up with "a slice of pi"


a slice of pi is irrational.


Even on special occasions?

Re: Slices and Dynamic Arrays

[Tony via Digitalmars-d-learn]

On Sunday, 31 December 2017 at 03:08:05 UTC, Ivan Trombley wrote:

double[] D = [3.14159];

Can you guess what D is?  :D


It took me a while but I finally came up with "a slice of pi"

Re: Slices and Dynamic Arrays

[Tony via Digitalmars-d-learn]

On Friday, 29 December 2017 at 23:13:20 UTC, Jonathan M Davis 
wrote:
The term "slice" is a bit overused in D, meaning a variety of 
things. It doesn't help that some folks dislike the official 
terminology. In general, a slice is a contiguous group of 
elements. A slice of memory would be a contiguous block of 
memory. A dynamic array therefore refers to a slice of memory 
and could be called a slice, but it's also the case that using 
the slice operater on a container is called slicing - e.g. 
rbt[] would give you a range over the container rbt, and that 
range is a slice of the container, but it's not an array at all.




For me, it is confusing to use "slice" and "dynamic array" as 
synonyms. My initial impression was that they must have different 
code underlying them, and different behavior. I would pick one or 
the other. It should be:


D Arrays
  - Static
  - Dynamic

or

D Arrays
   - Static
   - Slice


The DLang Tour has a section on Slices that says in bold "Slices 
and dynamic arrays are the same". I think that sentence deserves 
an explanation as to why there are two terms being utilized for 
the same thing. I would prefer that "slice" as a noun was used 
only for the time when a dynamic array was initialized from a 
slice of another array. Or better yet - slice was never used as a 
noun - only a verb or adjective: took a slice of array A to form 
a slice dynamic array B (or slice-intialized dynamic array B).


D Arrays
   - Static
   - Dynamic
  - Slice-Initialized Dynamic

Re: How do you safely deal with range.front?

[Tony via Digitalmars-d-learn]

For me, front() should throw a pre-defined exception when called 
on an empty range in order to eliminate undefined behavior. It 
does take some time to make a check, but D does array bounds 
checking by default. Ideally the front() check could be turned 
off somehow ("-boundschecks=off") by the user for those who want 
maximum speed, but I guess there is no way to do that when using 
pre-compiled functions in a library.

Slices and Dynamic Arrays

[Tony via Digitalmars-d-learn]

In DLang Tour:Arrays
https://tour.dlang.org/tour/en/basics/arrays

there is:
---
int size = 8; // run-time variable
int[] arr = new int[size];

The type of arr is int[], which is a slice.
---

In "D Slices"
https://dlang.org/d-array-article.html

there is:
---
int[] a; // a is a slice


Based on those two web pages it appears that the name for a 
dynamic array  in D is "slice". That is, anytime you 
have a dynamic array (even a null reference version) it is called 
a slice. Is that correct?

DLang Tour : Functions as arguments

[Tony via Digitalmars-d-learn]

On this page:
https://tour.dlang.org/tour/en/basics/delegates

there is:

void doSomething(int function(int, int) doer) {
// call passed function
doer(5,5);
}

doSomething(add); // use global function `add` here
  // add must have 2 int parameters



I can't get it to compile unless it is:

doSomething();

Ddoc - No Documentation

[Tony via Digitalmars-d-learn]

Wondering what the rationale is for this:

https://dlang.org/spec/ddoc.html#no_documentation

No Documentation

No documentation is generated for the following constructs, even 
if they have a documentation comment:


Invariants
Postblits
Destructors
Static constructors and static destructors
Class info, type info, and module info

Re: std.range.interfaces : InputRange moveFront

[Tony via Digitalmars-d-learn]

On Thursday, 30 November 2017 at 09:50:37 UTC, Tony wrote:

On Thursday, 30 November 2017 at 09:47:14 UTC, Tony wrote:

Thanks for the reply. Probably just missing it, but in poking 
around dlang.org (Language Reference and Library Reference) I 
am having trouble finding out about the move(), front() and 
moveFront() functions, as is used here on a dynamic array.


That should just be front() and moveFront() used here. I ran 
across move() in looking at the standard library for the 
definitions of the other two.


Found a move() here:
https://dlang.org/library/std/algorithm/mutation/move.html
Function std.algorithm.mutation.move

Re: std.range.interfaces : InputRange moveFront

[Tony via Digitalmars-d-learn]

On Thursday, 30 November 2017 at 09:47:14 UTC, Tony wrote:

Thanks for the reply. Probably just missing it, but in poking 
around dlang.org (Language Reference and Library Reference) I 
am having trouble finding out about the move(), front() and 
moveFront() functions, as is used here on a dynamic array.


That should just be front() and moveFront() used here. I ran 
across move() in looking at the standard library for the 
definitions of the other two.

Re: std.range.interfaces : InputRange moveFront

[Tony via Digitalmars-d-learn]

On Thursday, 30 November 2017 at 06:36:12 UTC, Ali Çehreli wrote:



move is an operation that transfers the state of the source to 
the destination. The front element becomes its .init value and 
its previous values is returned by moveFront().


The important bit is that, the element is *not* copied:

import std.range;

struct S {
int i;
bool is_a_copy = false;
this(this) {
is_a_copy = true;
}
}

void main() {
auto r =  [S(1)];

auto a = r.front;
assert(a.is_a_copy);   // yes, a is a copy
assert(a.i == 1);  // as expected, 1
assert(r.front.i == 1);// front is still 1

auto b = r.moveFront();
assert(!b.is_a_copy);  // no, b is not a copy
assert(b.i == 1);  // state is transferred
assert(r.front.i == 0);// front is int.init
}



Thanks for the reply. Probably just missing it, but in poking 
around dlang.org (Language Reference and Library Reference) I am 
having trouble finding out about the move(), front() and 
moveFront() functions, as is used here on a dynamic array.

std.range.interfaces : InputRange moveFront

[Tony via Digitalmars-d-learn]

What does the moveFront() method do in the InputRange interface?

std.range.interfaces : InputRange.moveFront()

Re: User defined type and foreach

[Tony via Digitalmars-d-learn]

On Saturday, 18 November 2017 at 05:24:30 UTC, Tony wrote:

Forgot to handle pre-mature foreach exit:

import std.stdio : writeln;

class RefRange {
int foreach_index;
int[] items;
this(int[] src)
{
   items = src;
}

bool empty()
{
   if (foreach_index == items.length)
   {
  foreach_index = 0; // reset for another foreach
  return true;
   }
   return false;
}
int front() { return items[foreach_index]; }
void popFront() { foreach_index++; }
void resetIteration() { foreach_index = 0; }
}

void main() {

int[] ints = [1, 2, 3];
auto refRange = new RefRange(ints);

writeln("Ref 1st Run:");
foreach(i; refRange)
{
   writeln(i);
   if ( i == 2 )
   {
  refRange.resetIteration();
  break;
   }
}
assert( ! refRange.empty);
writeln("Ref 2nd Run:");
foreach(i; refRange) writeln(i); // works
}
---
Ref 1st Run:
1
2
Ref 2nd Run:
1
2
3

Re: User defined type and foreach

[Tony via Digitalmars-d-learn]

On Friday, 17 November 2017 at 17:55:30 UTC, Jonathan M Davis 
wrote:


When you have

foreach(e; range)

it gets lowered to something like

for(auto r = range; !r.empty; r.popFront())
{
auto e = r.front;
}

So, the range is copied when you use it in a foreach. In the 
case of a class, it's just the reference that's copied. So, 
both "r" and "range" refer to the same object, but with a 
struct, you get two separate copies. So, when foreach iterates 
over "r", "range" isn't mutated.


Ah, I get it now ("r=range; process r"), thanks!



So, in the general case, if you want to use a range in foreach 
without consuming the range, it needs to be a forward range, 
and you need to call save. e.g.


foreach(e; range.save)



Seems like you can make class-based ranges to work on multiple 
foreach calls without having to do save, although maybe it falls 
apart in other usage. It also doesn't appear that the compiler 
requires an @property annotation as specified in the interface :


import std.stdio : writeln;

class RefRange {
int foreach_index;
int[] items;
this(int[] src)
{
   items = src;
}

bool empty()
{
   if (foreach_index == items.length)
   {
  foreach_index = 0; // reset for another foreach
  return true;
   }
   return false;
}
int front() { return items[foreach_index]; }
void popFront() { foreach_index++; }
}

void main() {
import std.stdio;

int[] ints = [1, 2, 3];
auto refRange = new RefRange(ints);

writeln("Ref 1st Run:");
foreach(i; refRange) writeln(i);
assert( ! refRange.empty);
writeln("Ref 2nd Run:");
foreach(i; refRange) writeln(i); // works
}
--
Ref 1st Run:
1
2
3
Ref 2nd Run:
1
2
3

Re: User defined type and foreach

[Tony via Digitalmars-d-learn]

On Friday, 17 November 2017 at 07:40:35 UTC, Mike Parker wrote:



You might also find use in this article (poorly adapted from 
Chapter 6 of Learning D by the publisher, but still readable):


https://www.packtpub.com/books/content/understanding-ranges

makes a distinction about "range consumption" with regard to a 
"reference type" or a "value type" and it isn't clear to me 
why there would be a difference.


With a value type, you're consuming a copy of the original 
range, so you can reuse it after. With a reference type, you're 
consuming the original range and therefore can't reuse it.




struct ValRange {
int[] items;
bool empty() @property { return items.length == 0; }
int front() @property { return items[0]; }
void popFront() { items = items[1 .. $]; }
}

class RefRange {
int[] items;
this(int[] src) { items = src; }
bool empty() @property { return items.length == 0; }
int front() @property { return items[0]; }
void popFront() { items = items[1 .. $]; }
}

void main() {
import std.stdio;

int[] ints = [1, 2, 3];
auto valRange = ValRange(ints);

writeln("Val 1st Run:");
foreach(i; valRange) writeln(i);
assert(!valRange.empty);

writeln("Val 2nd Run:");
foreach(i; valRange) writeln(i);
assert(!valRange.empty);

auto refRange = new RefRange(ints);

writeln("Ref 1st Run:");
foreach(i; refRange) writeln(i);
assert(refRange.empty);

writeln("Ref 2nd Run:");
foreach(i; refRange) writeln(i); // prints nothing
}


Thanks for the reference and the code. I will have to iterate 
over the packpub text a while consulting the docs. I see that the 
code runs as you say, but I don't understand what's going on. You 
say with regard to a "value type" : "you're consuming a copy of 
the original range" but I don't see anything different between 
the processing in the struct versus in the class. They both have 
a dynamic array variable that they re-assign a "slice" to (or 
maybe that is - that they modify to be the sliced version). 
Anyway, I can't see why the one in the struct shrinks and then 
goes back to what it was originally. It's like calls were made by 
the compiler that aren't shown.

Re: User defined type and foreach

[Tony via Digitalmars-d-learn]

On Friday, 17 November 2017 at 01:16:38 UTC, H. S. Teoh wrote:



It should be .empty, .popFront, and .front, not .pop.

Also, these methods are *range* primitives, and over time, we 
have come to a consensus that generally speaking, it's a bad 
idea to conflate containers with ranges over containers.  The 
main thing is that iterating over a range is supposed to 
consume it, which is usually not what you want with a container.


The usual idiom is to separate the two concepts, and have the 
container provide a mechanism for returning a range over its 
contents, usually via .opIndex with no arguments, or .opSlice. 
Then you would just write:


foreach (e; myContainer[]) { // [] calls .opIndex/.opSlice
...
}

Unfortunately, built-in arrays, which are also ranges, are one 
exception to this rule that, due to their ubiquity in D, also 
serve to mislead newcomers to D about when/where range 
primitives should be implemented. Generally speaking, built-in 
arrays should not be considered exemplary in this respect, but 
rather should be understood as exceptions.  The general 
convention is to separate your containers from ranges over its 
contents, and to provide .opIndex / .opSlice that constructs a 
range over the container when needed.


The other consideration is that if you don't really need range 
functionality, i.e., the only thing you want to do with your 
container is to put it in a foreach loop, then you can sidestep 
this whole mess and just implement .opApply for your container 
and call it a day.  Of course, then you won't be able to use 
generic algorithms like those in std.algorithm with your 
container, but if you didn't intend to anyway, it's not a big 
deal.



T


Thanks T! Good information, especially "iterating over a range is 
supposed to consume it". I have been reading 
dlang.org->Documentation->Language Reference, but  should have 
also read dlang.org->Dlang-Tour->Ranges. Although that page makes 
a distinction about "range consumption" with regard to a 
"reference type" or a "value type" and it isn't clear to me why 
there would be a difference.

Re: User defined type and foreach

[Tony via Digitalmars-d-learn]

On Thursday, 16 November 2017 at 18:34:54 UTC, Steven 
Schveighoffer wrote:

On 11/16/17 8:10 AM, ag0aep6g wrote:

On 11/16/2017 09:03 AM, Tony wrote:
However, when I use the class with foreach, the opindex gets 
called to create a dynamic array, rather than use the 
empty(),front(),popFront() routines. I would prefer it use 
the three methods, rather than create a dynamic array.


https://issues.dlang.org/show_bug.cgi?id=14619


I took a shot at fixing. Way more complex than I realized.



I was initially miffed that I had added empty(), popFront() and 
pop() and they weren't being used, but I don't have a problem 
with using [] instead of them. Maybe call it a feature and 
document it.


But I do have a complaint about the methods empty(), popFront() 
and pop(). I think they should have a special syntax or name to 
reflect that they are not general purpose methods. __empty() or 
preferably __forEachDone().  empty() is typically used to say if 
a container has no data,  not if you are at the end of external 
foreach loop processing. pop() and popFront() also would 
typically have different meanings with certain containers and 
their names don't reflect that they have a special "external 
foreach loop" purpose.

Re: User defined type and foreach

[Tony via Digitalmars-d-learn]

On Thursday, 16 November 2017 at 13:35:13 UTC, Tony wrote:

On Thursday, 16 November 2017 at 13:10:11 UTC, ag0aep6g wrote:

On 11/16/2017 09:03 AM, Tony wrote:
However, when I use the class with foreach, the opindex gets 
called to create a dynamic array, rather than use the 
empty(),front(),popFront() routines. I would prefer it use 
the three methods, rather than create a dynamic array.


https://issues.dlang.org/show_bug.cgi?id=14619


And also this one which was marked as a duplicate of yours

https://issues.dlang.org/show_bug.cgi?id=16374

"When lowering a foreach, the compiler gives priority to 
opSlice over front/popFront/empty, which is counter-intuitive 
(and also undocumented)."


 "opSlice" -> "opSlice or opIndex".


That should be "opSlice or opIndex-with-no-parameters"

Re: User defined type and foreach

[Tony via Digitalmars-d-learn]

On Thursday, 16 November 2017 at 13:10:11 UTC, ag0aep6g wrote:

On 11/16/2017 09:03 AM, Tony wrote:
However, when I use the class with foreach, the opindex gets 
called to create a dynamic array, rather than use the 
empty(),front(),popFront() routines. I would prefer it use the 
three methods, rather than create a dynamic array.


https://issues.dlang.org/show_bug.cgi?id=14619


And also this one which was marked as a duplicate of yours

https://issues.dlang.org/show_bug.cgi?id=16374

"When lowering a foreach, the compiler gives priority to opSlice 
over front/popFront/empty, which is counter-intuitive (and also 
undocumented)."


 "opSlice" -> "opSlice or opIndex".

Re: User defined type and foreach

[Tony via Digitalmars-d-learn]

On Thursday, 16 November 2017 at 12:56:18 UTC, Steven 
Schveighoffer wrote:

On 11/16/17 3:03 AM, Tony wrote:
I made a stack data type and created an opIndex() so it could 
be turned into a dynamic array, and created empty() 
(unfortunate name), front() and popFront() methods, which I 
read allow it to be used with foreach.


However, when I use the class with foreach, the opindex gets 
called to create a dynamic array, rather than use the 
empty(),front(),popFront() routines. I would prefer it use the 
three methods, rather than create a dynamic array.


Remove the opIndex, and see if it works. If it does, then this 
is a bug. The compiler should try to use the type as a range 
before seeing if opIndex gives it something.


Yes, if I remove opIndex() from the class, doing a foreach loop 
causes popFront(),empty(), and front() to be called and the 
foreach loop works.

Re: User defined type and foreach

[Tony via Digitalmars-d-learn]

On Thursday, 16 November 2017 at 08:26:25 UTC, Andrea Fontana 
wrote:

On Thursday, 16 November 2017 at 08:03:48 UTC, Tony wrote:
I made a stack data type and created an opIndex() so it could 
be turned into a dynamic array, and created empty() 
(unfortunate name), front() and popFront() methods, which I 
read allow it to be used with foreach.


However, when I use the class with foreach, the opindex gets 
called to create a dynamic array, rather than use the 
empty(),front(),popFront() routines. I would prefer it use the 
three methods, rather than create a dynamic array.


You can try to implement opApply().
Check:
http://ddili.org/ders/d.en/foreach_opapply.html


Thanks. Interesting that that page does not mention the behavior 
I am seeing, which is that foreach over a user-defined datatype 
can be implemented with only a 'T[] opIndex()' method.

User defined type and foreach

[Tony via Digitalmars-d-learn]

I made a stack data type and created an opIndex() so it could be 
turned into a dynamic array, and created empty() (unfortunate 
name), front() and popFront() methods, which I read allow it to 
be used with foreach.


However, when I use the class with foreach, the opindex gets 
called to create a dynamic array, rather than use the 
empty(),front(),popFront() routines. I would prefer it use the 
three methods, rather than create a dynamic array.

Re: Missing return value error not present with template

[Tony via Digitalmars-d-learn]

On Wednesday, 15 November 2017 at 11:20:24 UTC, Biotronic wrote:

Thanks Biotronic! I found this on the html documentation for 
templates: "The body of the TemplateDeclaration must be 
syntactically correct even if never instantiated. Semantic 
analysis is not done until instantiated", and that is a great 
explanation of why it is not semantically analyzed.

Missing return value error not present with template

[Tony via Digitalmars-d-learn]

This code:
class MyClass {

public:
   int SomeMethod ()
   {

   }

}


void main()
{

}

gets a compile error:
Error: function test_warnings.MyClass.SomeMethod has no return 
statement, but is expected to return a value of type int


but if I make it a template class:

class MyClass(T) {

there is no compile error. I don't know why the error isn't given 
for the template code as well.

Re: string version of array

[Tony via Digitalmars-d-learn]

On Tuesday, 14 November 2017 at 07:56:06 UTC, rikki cattermole 
wrote:

On 14/11/2017 7:54 AM, Tony wrote:
Is there an easy way to get the string representation of an 
array, as would be printed by writeln(), but captured in a 
string?


struct Foo {
int x;  
}

void main() {
Foo[] data = [Foo(1), Foo(2), Foo(3)];

import std.conv : text;
import std.stdio;

writeln(data.text);
}

---

[Foo(1), Foo(2), Foo(3)]


Thanks. That flipped function calling syntax definitely takes 
some getting used to.

string version of array

[Tony via Digitalmars-d-learn]

Is there an easy way to get the string representation of an 
array, as would be printed by writeln(), but captured in a string?

Re: core file

[Tony via Digitalmars-d-learn]

On Monday, 13 November 2017 at 07:38:14 UTC, Ali Çehreli wrote:



It is. If you search for "where is core file ubuntu" you will 
hit the output of 'man core', as well as answers like the 
following, which explains that the file may be under 
/var/cache/abrt:



https://stackoverflow.com/questions/2065912/core-dumped-but-core-file-is-not-in-current-directory


Thanks for the "man core" tip and the link.

Re: core file

[Tony via Digitalmars-d-learn]

On Monday, 13 November 2017 at 07:38:14 UTC, Ali Çehreli wrote:

On 11/12/2017 10:25 PM, Tony wrote:

>>> "Segmentation fault (core dumped)"

I've been assuming that if it says "dumped", the core is dumped.

> I am on Ubuntu 16.04. Thanks, I didn't know that "producing a
core file"
> was configurable, and it appears that it isn't.

It is. If you search for "where is core file ubuntu" you will 
hit the output of 'man core', as well as answers like the 
following, which explains that the file may be under 
/var/cache/abrt:



https://stackoverflow.com/questions/2065912/core-dumped-but-core-file-is-not-in-current-directory

Ali


My mistake. When I said "and it isn't", I was trying to say "and 
it isn't set on my system as shown by 'ulimit -a'".

Re: core file

[Tony via Digitalmars-d-learn]

On Monday, 13 November 2017 at 05:37:12 UTC, codephantom wrote:

On Monday, 13 November 2017 at 05:01:18 UTC, Tony wrote:

I am getting the message from my program execution:

"Segmentation fault (core dumped)"

But I don't see a core file in the current directory or in my 
home directory. Is there one somewhere? Would I be able to do 
anything meaningful with it if it exists?


More info than that is needed.

What platform are you on?

Do you have core dumps enabled/disabled?

If you have it enabled...where does it put them?

And yes, core dumps are potentially useful for debugging.

However, given you're asking that question, and getting core 
dumps, then it might be easier for you to use the -g option 
when you compile, and then run your executable (or a.out) 
through a debugger:


https://www.youtube.com/watch?v=vcVmWbYEIsk


I am on Ubuntu 16.04. Thanks, I didn't know that "producing a 
core file" was configurable, and it appears that it isn't.

core file

[Tony via Digitalmars-d-learn]

I am getting the message from my program execution:

"Segmentation fault (core dumped)"

But I don't see a core file in the current directory or in my 
home directory. Is there one somewhere? Would I be able to do 
anything meaningful with it if it exists?

Re: Conditional compilation of array of structs initializer

[Tony via Digitalmars-d-learn]

Thanks Mike!

Conditional compilation of array of structs initializer

[Tony via Digitalmars-d-learn]

Doing a port of some C code that has an #ifdef in the middle of 
an initialization for an array of structs. I am getting a compile 
error trying to get equivalent behavior with "static if" or 
"version". Is there a way to achieve this other than making two 
separate array initialization sections?


struct a {
   int y;
   int z;
}

immutable string situation = "abc";

int main()
{
   a[] theArray = [
  { 10, 20 },
// version(abc)
static if (situation == "abc")
{
  { 30, 40 },
}
  { 50, 60 }
  ];
   return 0;
}

Re: Any book recommendation for writing a compiler?

[Tony via Digitalmars-d-learn]

Author Allen Holub has made his out-of-print book, Compiler 
Design in C, available as a free pdf download:


http://holub.com/compiler/


And Torben Mogensen is doing the same with his more recent Basics 
of Compiler Design:


http://www.diku.dk/~torbenm/Basics/

Cyclic dependency error

[Tony via Digitalmars-d-learn]

My program compiled, but when I ran it I got this error message:

object.Error@src/rt/minfo.d(371): Cyclic dependency between 
module variable and main

variable* ->
misc ->
main* ->
variable*


I take it that the -> represents a dependency from the module on 
that line, to the module on the line below. My question is what 
do the asterisks represent?

fputs, stdout

[Tony via Digitalmars-d-learn]

There is a fputs/stdout in core.stdc.stdio.  std.stdio "public 
imports" that:


"public import core.stdc.stdio;"

Wondering why:

import core.stdc.stdio : fputs;
import core.stdc.stdio : stdout;

void main()
{
   fputs( cast(const char *)"hello world\n",stdout);
}

compiles and runs, but if I change the imports to:

import std.stdio : fputs;
import std.stdio : stdout;

I get this compile error:

fputs_test.d(11): Error: function core.stdc.stdio.fputs (scope 
const(char*) s, shared(_IO_FILE)* stream) is not callable using 
argument types (const(char*), File)

Re: Associative arrays with keys containing mutable indirections

[Tony via Digitalmars-d-learn]

I prefer the built-in associative array over using some template 
library. It has the clean look and ease-of-use that you get with 
a similar data structure in dynamic languages like Python. I 
consider it a top feature of D.

Re: Garbage Collector profiling and the dynamic array reserve() function

[Tony via Digitalmars-d-learn]

On Tuesday, 17 October 2017 at 13:27:24 UTC, Steven Schveighoffer 
wrote:




I don't know what "allocations" represents, but reserve 
actually calls gc_malloc, and the others do not (the space is 
available to expand into the block). There should be only one 
allocation IMO.


-Steve


So there should be a bug report written for this?

Garbage Collector profiling and the dynamic array reserve() function

[Tony via Digitalmars-d-learn]

Found this unanswered question on StackOverflow.

This program:

import std.stdio;

void add(ref int[] data)
{
data ~= 1;
data ~= 2;
}

void main()
{
int[] a;
writeln("capacity:",a.capacity);
auto cap = a.reserve(1000); // allocated may be more than 
requested

assert(cap >= 1000);
assert(cap == a.capacity);
writeln("capacity:",a.capacity);
a.add();
writeln(a);

}

compiled with "dmd -profile=gc"

has this output in profilegc.log

bytes allocated, allocations, type, function, file:line
  4   1 int[] profiling.add profiling.d:8
  4   1 int[] profiling.add profiling.d:7

The question is: why doesn't using reserve() cause an allocation 
to be shown?

Re: @property with 2 arguments

[Tony via Digitalmars-d-learn]

On Sunday, 1 October 2017 at 07:11:14 UTC, bitwise wrote:

On Sunday, 1 October 2017 at 05:57:53 UTC, Tony wrote:

"@property functions can only have zero, one or two parameters"

I am looking for an example of an @property function defined 
with two parameters and the syntax for how it is accessed 
without ().


And also this, which probably shouldn't actually work:

struct S {
@property void prop(int a, int b){}
}

int main(string[] argv)
{
S s;
s.prop = AliasSeq!(1, 2);
return 0;
}


Thanks! I was thinking it was something that looked like that, 
although the limitation to two items was puzzling.

Re: @property with 2 arguments

[Tony via Digitalmars-d-learn]

On Sunday, 1 October 2017 at 06:34:56 UTC, Jonathan M Davis wrote:
On Sunday, October 01, 2017 05:57:53 Tony via 
Digitalmars-d-learn wrote:

"@property functions can only have zero, one or two parameters"

I am looking for an example of an @property function defined 
with two parameters and the syntax for how it is accessed 
without ().


If it has two parameters, then it's a free function that can be 
used as a setter. e.g.


@property void foo(ref T t, int i)
{
...
}

myT.foo = 42;

- Jonathan M Davis


Thanks!

@property with 2 arguments

[Tony via Digitalmars-d-learn]

"@property functions can only have zero, one or two parameters"

I am looking for an example of an @property function defined with 
two parameters and the syntax for how it is accessed without ().

Re: Creating a dynamic library

[Tony via Digitalmars-d-learn]

On Saturday, 30 September 2017 at 10:09:43 UTC, Mike Wey wrote:

On 30-09-17 03:27, Tony wrote:
One thing I picked up from SCons is creating dynamic object 
files with a .os extension and static object files with the 
standard .o extension. That way they can be compiled in the 
same directory in the same build step. But dmd rejects the 
files that are named *.os. Is there an extension besides .o 
that dmd would accept for the dynamic object files?


I've been using .pic.o so it still ends with .o for dmd.


Thanks for the suggestion!

I was thinking that this might be a linker function only and 
tried to use g++ and gcc for the .so creation but, while they 
both create the same size file as each other, it is different 
than what dmd does when called with -shared.

Re: core.stdc.time

[Tony via Digitalmars-d-learn]

On Saturday, 30 September 2017 at 07:45:27 UTC, Jacob Carlborg 
wrote:

On 2017-09-30 08:56, Tony wrote:

The documentation says:
--
This module contains bindings to selected types and functions 
from the

standard C header . Note that this is not automatically
generated, and may omit some types/functions from the original 
C header.

---

It says "this is not automatically generated". I am seeing it 
on my
Ubuntu Linux system. What would cause it to not be generated 
and what

would be the solution?


It means that it's manually translated from C to D and not 
translated automatically using some tool.


Thanks!

core.stdc.time

[Tony via Digitalmars-d-learn]

The documentation says:
--
This module contains bindings to selected types and functions 
from the standard C header . Note that this is not 
automatically generated, and may omit some types/functions from 
the original C header.

---

It says "this is not automatically generated". I am seeing it on 
my Ubuntu Linux system. What would cause it to not be generated 
and what would be the solution?

Re: Creating a dynamic library

[Tony via Digitalmars-d-learn]

On Saturday, 30 September 2017 at 01:02:08 UTC, Elronnd wrote:

dmd bla.d bla2.d -shared -fPIC -oflibbla.so


Thanks. I don't normally compile right into a .so, but I think 
this is OK:


dmd my_file.o my_other_file.o  -shared   -of=libutest.so


One thing I picked up from SCons is creating dynamic object files 
with a .os extension and static object files with the standard .o 
extension. That way they can be compiled in the same directory in 
the same build step. But dmd rejects the files that are named 
*.os. Is there an extension besides .o that dmd would accept for 
the dynamic object files?

Creating a dynamic library

[Tony via Digitalmars-d-learn]

I would like to know that command line (I am on Linux) I would 
use to compile a D file and create an object file that is 
suitable for a Linux dynamic library (.so).


I believe it is probably

dmd -c -fPIC my_file.d

Also, what is the command line to create a dynamic library from 
one or more object files that have been compiled for dynamic 
invocation?


dmd ??? -shared ???

Re: Coverage (-cov)

[Tony via Digitalmars-d-learn]

On Sunday, 24 September 2017 at 05:48:32 UTC, Tony wrote:
I am compiling a module (utils) with one function in it with 
the -cov compiler option on Ubuntu 14.04 with DMD v2.073.2. I 
then compile a "main module" with -cov that imports the "utils 
module" and calls the one function. The *.lst output file shows 
lines that executed in the "main module". I would like it to 
also show lines that executed in the module that was imported. 
Is this possible?


Oops. Never mind. I just noticed the utils.lst output file.

Coverage (-cov)

[Tony via Digitalmars-d-learn]

I am compiling a module (utils) with one function in it with the 
-cov compiler option on Ubuntu 14.04 with DMD v2.073.2. I then 
compile a "main module" with -cov that imports the "utils module" 
and calls the one function. The *.lst output file shows lines 
that executed in the "main module". I would like it to also show 
lines that executed in the module that was imported. Is this 
possible?

How to set connect timeout on a blocking socket?

[tony via Digitalmars-d-learn]

Help me! How to set connect timeout on a blocking socket?

Re: Trying to compile weather program

[Tony via Digitalmars-d-learn]

I happened to notice that among my libcurl*s

libcurl-gnutls.so.3
libcurl-gnutls.so.4
libcurl-gnutls.so.4.3.0
libcurl.so.3
libcurl.so.4
libcurl.so.4.3.0

none were just libcurl.so. So I made a link for libcurl.so to the 
latest version and now I am getting the same link errors I got 
after downloading the -dev version. So apparently my can't find 
-lcurl was because I didn't have a non-versioned libcurl.so 
available as it went away when I created one (and there was 
probably one created by the -dev download).

Re: Trying to compile weather program

[Tony via Digitalmars-d-learn]

On Monday, 24 August 2015 at 06:28:34 UTC, Yazan D wrote:

On Sun, 23 Aug 2015 16:00:16 +, Tony wrote:

Thanks for the replies. It compiles OK with just. However, it 
isn't linking:


/usr/bin/ld: cannot find -lcurl


I do have some versions of libcurl on my system:

/usr/lib/x86_64-linux-gnu/libcurl.so.3 
/usr/lib/x86_64-linux-gnu/libcurl.so.4.3.0 
/usr/lib/x86_64-linux-gnu/libcurl.so.4


I see there is a -L option to pass things to the linker

-Llinkerflag   pass linkerflag to link

but I am not sure how to use it.


I've had the same problem recently. What I did was that I ran 
`dmd main.d
-L-L/usr/lib/x86_64-linux-gnu/ -L-lcurl -v`. It would still 
fail to link,
but I can find the linking command from the verbose output. It 
was
something like this: `gcc main.o -o main -m64 
-L/usr/lib/x86_64-linux-
gnu/ -lcurl -L/usr/lib/x86_64-linux-gnu -Xlinker 
--export-dynamic -

l:libphobos2.a -lpthread -lm -lrt`.
As you can see, -lcurl is there, but it still needs to be added 
again
after -l:libphobos2.a. So just add it again so the command 
becomes:
`gcc main.o -o main -m64 -L/usr/lib/x86_64-linux-gnu/ -lcurl 
-L/usr/lib/
x86_64-linux-gnu -Xlinker --export-dynamic -l:libphobos2.a 
-lpthread -lm -

lrt -lcurl`. And it links and runs.


I  had an additional -lcurl in already in my output, but added 
another at the end:


gcc weather_report.o -o weather_report -m64 
-L/usr/lib/x86_64-linux-gnu/ -lcurl -L/usr/lib/x86_64-linux-gnu 
-Xlinker --export-dynamic -lcurl -l:libphobos2.a -lpthread -lm 
-lrt -lcurl


but it still complains that it cannot find -lcurl.  It even does 
it if I add -lcurl everywhere:


gcc weather_report.o -o weather_report -m64 
-L/usr/lib/x86_64-linux-gnu/ -lcurl -L/usr/lib/x86_64-linux-gnu 
-Xlinker --export-dynamic -lcurl -l:libphobos2.a -lcurl -lpthread 
-lcurl -lm -lrt -lcurl


As an aside, I remember having to add additional mentions of a 
library in a link line years ago on Unix. I am surprised they 
haven't changed the way it works so that you only have to mention 
it once.

Re: Trying to compile weather program

[Tony via Digitalmars-d-learn]

On Sunday, 23 August 2015 at 16:20:04 UTC, Gerald Jansen wrote:

On Sunday, 23 August 2015 at 16:00:19 UTC, Tony wrote:

/usr/bin/ld: cannot find -lcurl


Just the other day I had a similar problem (compiling vibenews, 
ld complained of missing -levent and -lssl), which I managed to 
solve simply by installing the development versions of the 
libraries (i.e. libevent-dev and libssl-dev). Maybe if you 
install libcurl-dev you will have the same luck I had. (But 
hopefully someone will give a more enlightened reply.)


Synaptic gave me a choice of 3 libcurl*
libcurl4-nss-dev (NSS flavour)
libcurl4-gnutls-dev (GnuTLS flavour)
libcurl4-openssl-dev (OpenSSL flavour)

Confusing that there are 3 choices.

I downloaded the OpenSSL one and the can't find lcurl has gone 
away. But I am now getting linking errors with regard to curl 
certain curl functions not being found.

Re: Trying to compile weather program

[Tony via Digitalmars-d-learn]

On Sunday, 23 August 2015 at 16:00:19 UTC, Tony wrote:
Thanks for the replies. It compiles OK with just. However, it 
isn't linking:


/usr/bin/ld: cannot find -lcurl


I do have some versions of libcurl on my system:

/usr/lib/x86_64-linux-gnu/libcurl.so.3
/usr/lib/x86_64-linux-gnu/libcurl.so.4.3.0
/usr/lib/x86_64-linux-gnu/libcurl.so.4

I see there is a -L option to pass things to the linker

-Llinkerflag   pass linkerflag to link

but I am not sure how to use it.


I tried

ld weather_report.o -lcurl -L/usr/lib/x86_64-linux-gnu

and

ld weather_report.o -lcurl -L /usr/lib/x86_64-linux-gnu

but it also says it can't find libcurl:

ld: cannot find -lcurl

Re: Trying to compile weather program

[Tony via Digitalmars-d-learn]

Thanks for the replies. It compiles OK with just. However, it 
isn't linking:


/usr/bin/ld: cannot find -lcurl


I do have some versions of libcurl on my system:

/usr/lib/x86_64-linux-gnu/libcurl.so.3
/usr/lib/x86_64-linux-gnu/libcurl.so.4.3.0
/usr/lib/x86_64-linux-gnu/libcurl.so.4

I see there is a -L option to pass things to the linker

-Llinkerflag   pass linkerflag to link

but I am not sure how to use it.

Trying to compile weather program

[Tony via Digitalmars-d-learn]

I found this weather program on the main page (it seems to rotate 
what it here):


// Get your local weather report
pragma(lib, curl);
import std.functional, std.json, std.net.curl,
std.stdio, std.string;

alias getJSON = pipe!(get, parseJSON);
auto K2C = (float f) = f - 273.15;
auto K2F = (float f) = f / 5 * 9 - 459.67;

void main()
{
auto loc = getJSON(ipinfo.io/)[loc]
.str.split(,);
auto resp = getJSON(
api.openweathermap.org/data/2.5/weather ~
?lat= ~ loc[0] ~ lon= ~ loc[1]);

auto city = resp[name].str;
auto country = resp[sys][country].str;
auto desc = resp[weather][0][description].str;
auto temp = resp[main][temp].floating;

writefln(`
+-+
|%s|
+-+
|  weather  |  %-23s|
+-+
|  temperature  |  %.2f°C (%.2f°F)  |
+-+
`.outdent,
centerJustifier(city ~ ,  ~ country, 41),
desc, temp.K2C, temp.K2F);
}

I am compiling on Ubuntu 14.02 with DMD v2.066.1

I get this compile error:

weather_report.d(32): Error: undefined identifier centerJustifier

main() return code.

[Tony via Digitalmars-d-learn]

Why is it acceptable to specify main as returning void (in 
addition to returning int)?

website update

[Tony via Digitalmars-d-learn]

It looks like this page:

http://dlang.org/hash-map.html

Should have the override keyword added the the member functions 
in Foo:


class Foo
{
int a, b;

size_t toHash() { return a + b; }

bool opEquals(Object o)
{
Foo foo = cast(Foo) o;
return foo  a == foo.a  b == foo.b;
}
}