__traits(getDelegate, ...)

[Andrei Alexandrescu]

On 2/4/13 12:32 AM, Steven Schveighoffer wrote:
> On Mon, 04 Feb 2013 00:20:22 -0500, Andrei Alexandrescu
> <SeeWebsiteForEmail at erdani.org> wrote:
>
>> On 2/4/13 12:14 AM, Steven Schveighoffer wrote:
>>> Turns out, it's somewhat possible to specify, but it can be
>>> painful/uintuitive:
>>>
>>> auto dg = cast(void delegate(string))&s.foo; // oops, what if I use the
>>> wrong delegate signature, or S.foo is changed later!
>>
>> void delegate(string) dg = &s.foo;
>
> That seems, ... odd. How does the lhs dictate the rhs expression type?
>
> Trying to think of a case where an expression is more handy than
> assigning to a variable first...
>
> Possibly this? Kind of a stretch.
>
> void delayedCall(D)(D dg)
> {
> // put dg as a delegate onto a message queue to call later...
> }
>
> -Steve

This is well-trodden ground. The rule has been in C++ forever and has 
worked well. It's time-proven, and there is little reason to mess with 
what works.

Andrei