[Issue 10193] Template args to UDA's

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=10193


Kenji Hara <k.hara.pg at gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |INVALID


--- Comment #1 from Kenji Hara <k.hara.pg at gmail.com> 2013-05-28 08:48:27 PDT ---
(In reply to comment #0)
> Doesn't work:
>   @attribute("target", T) void func(string T)(...);

You can write it as follows.

string attribute(string, string s) { return s; }
template func(string T)
{
    @attribute("target", T) void func() {}
}

void main()
{
    alias f1 = func!"a";
    alias f2 = func!"b";
    pragma(msg, __traits(getAttributes, f1));   // "a"
    pragma(msg, __traits(getAttributes, f2));   // "b"
    f1();
    f2();
}

----

It looks reasonable enhancement, but in general case it would introduce not
trivial semantic issue.

Based on the current D language spec, prefix attribute is just rewritten to
blocked attribute.

@attribute("target", T) void func(string T)() {}

to:
@attribute("target", T) { void func(string T)() {} }

And block attribute can contain other declarations.

@attribute("target", T) {

    enum str = T.stringof;

    void func(string T)() {}
}

Well, if the enhancement is implemented, T would be deduced by the each call of
template function foo. Then the enum value would become undeterministic.

I think it is not implementable.

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