Using a macro for a function signature

[ag0aep6g via Digitalmars-d-learn]

On 05.04.2016 13:35, pineapple wrote:
> alias somelongsignature = int(in int x);

alias somelongsignature = int function(in int);

Or if you want to accept methods and such:

alias somelongsignature = int delegate(in int);

You can name the parameter, but it won't be part of the type.

> int examplefunc0(in int x){
>      return x * 2;
> }
>
> somelongsignature testfunc0 = examplefunc1;

somelongsignature testfunc0 = &examplefunc0;

Note the ampersand.

> somelongsignature testfunc1 = somelongsignature {return x + 3};

I don't think there's a way to do this as nicely as you want.

One thing you can do is declare the parameters without types:

somelongsignature testfunc1 = (x) {return x + 3;};

Saves you some typing, especially with complicated parameter types.

Another thing is std.traits.Parameters:

alias F = int function(int, float, string, void*);
import std.traits: Parameters;
F testfunc2 = (Parameters!F args) {return args[0] + 3;};

This way you don't have to type out a long list of parameters, but 
`args[0]` isn't as nice as `x`, of course.

There may be a way to transfer the parameter names as well, but I 
suspect that's going to be a little more fiddly.