[phobos] expand for std.metastrings

[Andrei Alexandrescu]

One more thing - for efficiency, instead of using to!string, I suggest 
you use formattedWrite with "%s" as format string and an appender as writer.

Andrei

On 11/2/10 5:40 AM, kenji hara wrote:
> Thanks for your response, Andrei.
>
> I applied improvements that suggested from you.
> - Identifier expression currently does not require braces.
> - Interpolation expression is converted to string implicitly (with
> std.conv.to!string(...)).
>
> It is still not renamed to 'inter' in github, but I would to do it
> when committing to Phobos.
>
> Kenji Hara
>
> 2010/11/2 Andrei Alexandrescu<andrei at erdani.com>:
>> This is great. It's funny I was thinking the same this morning before having
>> looked over this message.
>>
>> As expansion using $xxx is called interpolation in Perl and probably other
>> scripting languages I suggest we call the facility "inter".
>>
>> We can use it with writeln, which I think will be quite popular:
>>
>> int a = 2;
>> string b = "hello";
>> writeln(mixin(inter!"I told you $a times: $str!"));
>>
>> As shown above, I also suggest that we don't require {} when the expression
>> is an identifier.
>>
>> A debatable language change would allow us to eliminate "mixin", as it has
>> been discussed in the newsgroup. A simpler and less dangerous change would
>> be to make the paren optional:
>>
>> writeln(mixin inter!"I told you $a times: $str!");
>>
>>
>>
>> Andrei
>>
>> On 10/31/10 10:50 AM, kenji hara wrote:
>>>
>>> I wrote a trivial utility template for generating code string.
>>> This provides some easiness and viewability of metaprogramming.
>>> (This is currently used in my adaptTo.)
>>>
>>> http://github.com/9rnsr/scrap/blob/master/expand/expand.d
>>>
>>> Sample:
>>> ----
>>> template GenFunc(string name)
>>> {
>>>    mixin(
>>>      mixin(expand!q{
>>>        int ${name}(){ return 10; }
>>>      }));
>>>    // result of expand! is:
>>>    //   q{`int ` ~ name ~ `(){ return 10; }`}
>>> }
>>> mixin GenFunc!("test");   // generates function "test" returns int
>>> unittest{
>>>    assert(test() == 10);
>>> }
>>> ----
>>>
>>> expand!q{ codes... } parses D code string, and expands ${ expr } for
>>> embedding expr that is expression evaluated as string in compile-time.
>>>
>>> do you think?
>>>
>>> Kenji
>>> _______________________________________________
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>>
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