I was waiting for a stable version of C++17 ( standard library ) to add some features of fileSystem in C++17 to my program that wants to iterate through all files in a directory recursively.

I was thinking how could I do for implementing that and add it to my program.

Now after starting to learn D ( nearby 2 weeks so far ). I can do it in 6 lines!

void main( string[] args ){
	
	string[] all_file_name =  dirEntries( ".", SpanMode.depth, false )
         .filter!( file => !file.name.matchFirst( regex( args[ 1 ] ) ).empty() )
         .filter!( file => ( args[ 2 ] == "-f" || args[ 2 ] == "-d"  ? ( args[ 2 ] == "-f" ? !file.isDir : !file.isFile ) : ( !file.isSymlink ) ) )
	 .map!( file => file.name )
	 .array;
	foreach( string item; all_file_name ) writeln( item );
	
}

./bin-file '[A-Z]$' -f   ---> print all files that are matched against [A-Z]$

./bin-file '[A-Z]$' -d   ---> print all directory that are matched against [A-Z]$

./bin-file '[A-Z]$' "anything-else"  ---> print both files and directory that are matched against [A-Z]$

I am so happy since after more than one year practicing in C++ and putting a collection more than 2000 examples of C++ on my github, I was not sure I could do it in 6 lines.

May it is a Spam but I think it is worth it.

On Friday, 12 May 2017 at 11:10:01 UTC, k-five wrote:
> I was waiting for a stable version of C++17 ( standard library ) to add some features of fileSystem in C++17 to my program that wants to iterate through all files in a directory recursively.
>
> I was thinking how could I do for implementing that and add it to my program.
>
> Now after starting to learn D ( nearby 2 weeks so far ). I can do it in 6 lines!
>
> void main( string[] args ){
> 	
> 	string[] all_file_name =  dirEntries( ".", SpanMode.depth, false )
>          .filter!( file => !file.name.matchFirst( regex( args[ 1 ] ) ).empty() )
>          .filter!( file => ( args[ 2 ] == "-f" || args[ 2 ] == "-d"  ? ( args[ 2 ] == "-f" ? !file.isDir : !file.isFile ) : ( !file.isSymlink ) ) )
> 	 .map!( file => file.name )
> 	 .array;
> 	foreach( string item; all_file_name ) writeln( item );
> 	
> }
>
> ./bin-file '[A-Z]$' -f   ---> print all files that are matched against [A-Z]$
>
> ./bin-file '[A-Z]$' -d   ---> print all directory that are matched against [A-Z]$
>
> ./bin-file '[A-Z]$' "anything-else"  ---> print both files and directory that are matched against [A-Z]$
>
> I am so happy since after more than one year practicing in C++ and putting a collection more than 2000 examples of C++ on my github, I was not sure I could do it in 6 lines.
>
> May it is a Spam but I think it is worth it.

Shorter:

void main( string[] args ){
	dirEntries( ".", SpanMode.depth, false )
         .filter!( file => !file.name.matchFirst( regex( args[ 1 ] ) ).empty() )
         .filter!( file => ( args[ 2 ] == "-f" || args[ 2 ] == "-d"  ? ( args[ 2 ] == "-f" ? !file.isDir : !file.isFile ) : ( !file.isSymlink ) ) )
	 .map!( file => file.name )
	 .each!(string item => writeln( item ));
}

It's more memory efficient too because at no point the actual list is stored.

On Friday, 12 May 2017 at 11:41:57 UTC, cym13 wrote:
> On Friday, 12 May 2017 at 11:10:01 UTC, k-five wrote:
-------------------------------------------------------
>
> Shorter:
>
> void main( string[] args ){
> 	dirEntries( ".", SpanMode.depth, false )
>          .filter!( file => !file.name.matchFirst( regex( args[ 1 ] ) ).empty() )
>          .filter!( file => ( args[ 2 ] == "-f" || args[ 2 ] == "-d"  ? ( args[ 2 ] == "-f" ? !file.isDir : !file.isFile ) : ( !file.isSymlink ) ) )
> 	 .map!( file => file.name )
> 	 .each!(string item => writeln( item ));
> }
>
> It's more memory efficient too because at no point the actual list is stored.
---------------------------------------------------------

Thanks and the correct syntax for each! is, passing a lambda. So the:
> 	 .each!(string item => writeln( item ));
is an error:
temp.d(15): Error: found 'item' when expecting ')' following template argument list ...

and should be:
.each!( ( string item )  => writeln( item ) );

On Friday, 12 May 2017 at 11:58:23 UTC, k-five wrote:
> On Friday, 12 May 2017 at 11:41:57 UTC, cym13 wrote:
>> [...]
> -------------------------------------------------------
>> [...]
> ---------------------------------------------------------
>
> Thanks and the correct syntax for each! is, passing a lambda. So the:
>> [...]
> is an error:
> temp.d(15): Error: found 'item' when expecting ')' following template argument list ...
>
> and should be:
> .each!( ( string item )  => writeln( item ) );

Ah, yeah, my bad, I should have try compiling it instead of answering directly ;)

On Friday, 12 May 2017 at 11:10:01 UTC, k-five wrote:
> I was waiting for a stable version of C++17 ( standard library ) to add some features of fileSystem in C++17 to my program that wants to iterate through all files in a directory recursively.
>
> I was thinking how could I do for implementing that and add it to my program.
>
> Now after starting to learn D ( nearby 2 weeks so far ). I can do it in 6 lines!

Thumbs up, nice post!

Bastiaan.

12.05.2017 14:58, k-five пишет:
> On Friday, 12 May 2017 at 11:41:57 UTC, cym13 wrote:
>> On Friday, 12 May 2017 at 11:10:01 UTC, k-five wrote:
> -------------------------------------------------------
>>
>> Shorter:
>>
>> void main( string[] args ){
>>     dirEntries( ".", SpanMode.depth, false )
>>          .filter!( file => !file.name.matchFirst( regex( args[ 1 ] )
>> ).empty() )
>>          .filter!( file => ( args[ 2 ] == "-f" || args[ 2 ] == "-d"  ?
>> ( args[ 2 ] == "-f" ? !file.isDir : !file.isFile ) : ( !file.isSymlink
>> ) ) )
>>      .map!( file => file.name )
>>      .each!(string item => writeln( item ));
>> }
>>
>> It's more memory efficient too because at no point the actual list is
>> stored.
> ---------------------------------------------------------
>
> Thanks and the correct syntax for each! is, passing a lambda. So the:
>>      .each!(string item => writeln( item ));
> is an error:
> temp.d(15): Error: found 'item' when expecting ')' following template
> argument list ...
>
> and should be:
> .each!( ( string item )  => writeln( item ) );

also .each!writeln should be possible

On Friday, 12 May 2017 at 12:56:50 UTC, drug wrote:
> 12.05.2017 14:58, k-five пишет:
>> On Friday, 12 May 2017 at 11:41:57 UTC, cym13 wrote:
>>> On Friday, 12 May 2017 at 11:10:01 UTC, k-five wrote:
>> -------------------------------------------------------
> also .each!writeln should be possible
---------------------------------------------------------

Yes. Worked. Thanks

On Friday, 12 May 2017 at 11:10:01 UTC, k-five wrote:
> I was waiting for a stable version of C++17 ( standard library ) to add some features of fileSystem in C++17 to my program that wants to iterate through all files in a directory recursively.
>
> I was thinking how could I do for implementing that and add it to my program.
>
> Now after starting to learn D ( nearby 2 weeks so far ). I can do it in 6 lines!
>
> void main( string[] args ){
> 	
> 	string[] all_file_name =  dirEntries( ".", SpanMode.depth, false )
>          .filter!( file => !file.name.matchFirst( regex( args[ 1 ] ) ).empty() )
>          .filter!( file => ( args[ 2 ] == "-f" || args[ 2 ] == "-d"  ? ( args[ 2 ] == "-f" ? !file.isDir : !file.isFile ) : ( !file.isSymlink ) ) )
> 	 .map!( file => file.name )
> 	 .array;
> 	foreach( string item; all_file_name ) writeln( item );
> 	
> }
>
> ./bin-file '[A-Z]$' -f   ---> print all files that are matched against [A-Z]$
>
> ./bin-file '[A-Z]$' -d   ---> print all directory that are matched against [A-Z]$
>
> ./bin-file '[A-Z]$' "anything-else"  ---> print both files and directory that are matched against [A-Z]$
>
> I am so happy since after more than one year practicing in C++ and putting a collection more than 2000 examples of C++ on my github, I was not sure I could do it in 6 lines.
>
> May it is a Spam but I think it is worth it.

------------------------------------------------------------------

May it has worth it to be an example on how great D is, in somewhere like, in the tour section or std.file or std.regex to attract others.

A full version that I just added to my gitgub: https://github.com/k-five/dren

On Friday, 12 May 2017 at 15:24:52 UTC, k-five wrote:
> On Friday, 12 May 2017 at 11:10:01 UTC, k-five wrote:
>> I was waiting for a stable version of C++17 ( standard library ) to add some features of fileSystem in C++17 to my program that wants to iterate through all files in a directory recursively.
>>
>> I was thinking how could I do for implementing that and add it to my program.
>>
>> Now after starting to learn D ( nearby 2 weeks so far ). I can do it in 6 lines!
>>
>> void main( string[] args ){
>> 	
>> 	string[] all_file_name =  dirEntries( ".", SpanMode.depth, false )
>>          .filter!( file => !file.name.matchFirst( regex( args[ 1 ] ) ).empty() )
>>          .filter!( file => ( args[ 2 ] == "-f" || args[ 2 ] == "-d"  ? ( args[ 2 ] == "-f" ? !file.isDir : !file.isFile ) : ( !file.isSymlink ) ) )
>> 	 .map!( file => file.name )
>> 	 .array;
>> 	foreach( string item; all_file_name ) writeln( item );
>> 	
>> }
>>
>> ./bin-file '[A-Z]$' -f   ---> print all files that are matched against [A-Z]$
>>
>> ./bin-file '[A-Z]$' -d   ---> print all directory that are matched against [A-Z]$
>>
>> ./bin-file '[A-Z]$' "anything-else"  ---> print both files and directory that are matched against [A-Z]$
>>
>> I am so happy since after more than one year practicing in C++ and putting a collection more than 2000 examples of C++ on my github, I was not sure I could do it in 6 lines.
>>
>> May it is a Spam but I think it is worth it.
>
> ------------------------------------------------------------------
>
> May it has worth it to be an example on how great D is, in somewhere like, in the tour section or std.file or std.regex to attract others.
>
> A full version that I just added to my gitgub: https://github.com/k-five/dren

Is it safe to say that these 40 lines of D do the same as your 324 lines of C++ [1]? This, and your comments on the difficulties of building renrem [2] versus doing "rdmd", and the steepness of the learning curve (1 year C++ vs 2 weeks D), and the productivity (2 hours D vs ?? C++) I think are plenty material for a nice little blog.

Mike Parker runs the D blog, and I think he might be interested. No need to worry about the english language, you are safe with Mike. I'll see if I can get you his attention.

[1] https://github.com/k-five/renrem
[2] https://github.com/k-five/renrem/blob/master/src/README.md
[3] https://dlang.org/blog/

On Friday, 12 May 2017 at 15:24:52 UTC, k-five wrote:
> A full version that I just added to my gitgub: https://github.com/k-five/dren

You may like getopt[1] for command line argument parsing.

https://dlang.org/phobos/std_getopt.html