What does __parameters return?

[simendsjo]

On Thursday, 12 September 2013 at 21:33:48 UTC, Andrej Mitrovic 
wrote:
> On 9/12/13, simendsjo <simendsjo at gmail.com> wrote:
>> Thanks. I just ended up using both is(__parameters and
>> is(function to fetch the parameter names. Sometimes it seems
>> things are added to D without a very thorough design phase, but
>> then again, it starts with "__", so I guess I'm on my own :)
>
> Have you tried using ParameterIdentifierTuple from std.traits?

The problem with this is that you need to supply the symbol. If 
you are located inside an overloaded function, you will get the 
first function defined when using the function name. This means 
you'll have to look at the parent, get overloads, and then find 
the correct overload (the one you're currently in) by doing some 
__parameters hacking.

And if you're in a templated function, it looks even worse. Seems 
I cannot get the "overloads" of a template.

So my solution is to use a mixin template..

The template itself defines a dummy variable (so you don't have 
to pass a symbol), use __traits(parent), and then use 
__parameters and __traits(function) to find the names.

Of course, calling ParameterIdentifierTuple!(__traits(parent ... 
in the mixin template simplifies the implementation quite a bit.

Didn't know you could call __traits(identifier for the 
__parameter values. __parameters is practically undocumented, and 
doesn't even have an example.