[phobos] expand for std.metastrings

[Andrei Alexandrescu]

Indeed, sorry.

I think expand is fine with me too.

Simen - I think a good motivation can be found in Terence Parr's 
StringTemplate documentation, for example:

http://www.antlr.org/wiki/display/ST/Introduction

Andrei

On 11/2/10 11:05 AM, kenji hara wrote:
> 1) Appender does not work at compile time.
> 2) I assume that interp is mainly used for code generation.
>      So, I think the cost of implementing and the purpose are incongruous.
>
> Kenji
>
> 2010/11/2 Andrei Alexandrescu<andrei at erdani.com>:
>> 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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