[Issue 7135] [tdpl] Multiple delegate-related issues (literal syntax, @system deduction)

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=7135



--- Comment #8 from Kenji Hara <k.hara.pg at gmail.com> 2012-01-01 05:56:47 PST ---
(In reply to comment #7)
> One more thing - the example in the book reads:
> 
>   obj.addMethod("sayHello",
>       Variant(Dynamic, Variant[]...) {
>         writeln("Hello, world!");
>         return Variant();
>      });
> 
> That doesn't work. The compilable version reads:
> 
> obj.addMethod("sayHello",
>       delegate Variant(Dynamic, Variant[]...) {
>         writeln("Hello, world!");
>         return Variant();
>      });
> 
> Can we arrange things such that the "delegate" or "function" keywords aren't
> require in the literal definition?

>From past, omission of delegate keyword +  specification of return type has
been wrong syntax. So Variant(Dynamic, Varinat[]...) { ... } couldn't compile.

And recent commit

https://github.com/D-Programming-Language/dmd/commit/c50eb5f5726a65efa1224ff0f0fd60acbb6e3027

has been disallowed optional parameter names, because of parameter type
inference.

>From these matters, current TDPL code never become valid.

----

Today, following literal notations has been allowed with current dmd.

delegate Variant(Dynamic self, Variant[] args...) {...}
delegate (Dynamic self, Variant[] args...) {...}
(Dynamic self, Variant[] args...) {...}

----

Note: Unfortunately, current dmd does not support parameter type inference +
type-safe variadisc like follows.

//delegate (self, args...) {...}
//(self, args...) {...}

Because args could have three kind of infer targets.

T[N] args...    // T is the element type of args
T[] args...     // T is the element type of args
T args...       // T is class type, and args is translated to new T(args)

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