After reading about rdmd and --eval, I tried this:

rdmd --eval='auto f=File("ddoc.html");foreach(line;f.byLine) if(line.length<10) writeln(line);f.close'

and worked!

Now I am wonder if there is a way to pass "ddoc.html" to this one-liner? that can work with --loop.

I mean:
// --loop by default has foreach(line ...
// like perl -n
rdmd --loop='if( line.length < 10 ) writeln( line );' ddoc.html

but it is an error in syntax and rdmd says:
Cannot have both --eval and a program file ('ddoc.html')

On Sunday, 7 May 2017 at 10:49:25 UTC, k-five wrote:
> After reading about rdmd and --eval, I tried this:
>
> rdmd --eval='auto f=File("ddoc.html");foreach(line;f.byLine) if(line.length<10) writeln(line);f.close'
>
> and worked!
>
> Now I am wonder if there is a way to pass "ddoc.html" to this one-liner? that can work with --loop.
>
> I mean:
> // --loop by default has foreach(line ...
> // like perl -n
> rdmd --loop='if( line.length < 10 ) writeln( line );' ddoc.html
>
> but it is an error in syntax and rdmd says:
> Cannot have both --eval and a program file ('ddoc.html')

Currently it's not possible:

On Sunday, 7 May 2017 at 11:11:05 UTC, Vladimir Panteleev wrote:
> Currently it's not possible:

https://issues.dlang.org/show_bug.cgi?id=13345

On Sunday, 7 May 2017 at 11:11:05 UTC, Vladimir Panteleev wrote:
> On Sunday, 7 May 2017 at 10:49:25 UTC, k-five wrote:
>> After reading about rdmd and --eval, I tried this:
>>
>> rdmd --eval='auto f=File("ddoc.html");foreach(line;f.byLine) if(line.length<10) writeln(line);f.close'
>>
>> and worked!
>>
>> Now I am wonder if there is a way to pass "ddoc.html" to this one-liner? that can work with --loop.
>>
>> I mean:
>> // --loop by default has foreach(line ...
>> // like perl -n
>> rdmd --loop='if( line.length < 10 ) writeln( line );' ddoc.html
>>
>> but it is an error in syntax and rdmd says:
>> Cannot have both --eval and a program file ('ddoc.html')
>
> Currently it's not possible:

It should be possible!
rdmd --eval=, without accepting argument is useless.

On Sunday, 7 May 2017 at 11:29:30 UTC, k-five wrote:
> It should be possible!
> rdmd --eval=, without accepting argument is useless.

FWIW, you can still pass input through stdin.

On Sunday, 7 May 2017 at 13:45:37 UTC, Vladimir Panteleev wrote:
> On Sunday, 7 May 2017 at 11:29:30 UTC, k-five wrote:
>> It should be possible!
>> rdmd --eval=, without accepting argument is useless.
>
> FWIW, you can still pass input through stdin.

Well how about --build-only?
with this argument it would be better to create executable file in the current directory not in the /tmp/.rddmd-1000/ and with a name like: eval.E201596D1C1E063AACF70666A4DBE264
This is a very useful tool if had some feature of awk and some of perl

Unfortunately I only for a two weeks long got involved with leaning D, if I had experience with D I make it so nicer.
-e is better than --eval
-n is better than --loop
because a one-liner should be as short as possible.

Anyways thanks for replay.
Also your website: http://thecybershadow.net/d/dconf2016/ was so nice.