Two things I thought would be simple

[Steven Schveighoffer]

On 3/7/18 9:20 AM, Shachar Shemesh wrote:
> import std.traits;
> import std.stdio;
> 
> void func(int a, int b=2, int c=3) {
>      return a+b+c;
> }
> 
> void func2(Parameters!func args = ParameterDefaults!func) {
>      return func(args);
> }
> 
> void main() {
>      writeln(func2(1));
>      writeln(func2(1,1));
>      writeln(func2(1,1,1));
> }
> 
> So, this does not compile. I can do that with a mixin, but I would much 
> rather not. Is there a non-Mixin method of copying not only the 
> function's signature, but also its default values?

Well, you could do it with templates, but obviously that is less desirable:

void func2(Args...)(Args args) if(is(typeof(func(args)))) { return 
func(args); }

> The second thing I thought would be simple is to refer to call a 
> struct's member.
> 
> struct S {
>      void func(int a) {
>      }
> }
> 
> unittest {
>      alias v = S.func;

This is actually a function that requires a `this` pointer. It can't be 
called unless you stuff it in a delegate:

> 
>      S s;
>      s.v(12); // No property v for type S

void delegate(int) dg;
dg.ptr = &s;
dg.funcptr = &v; // note you need the address operator

>      // UFCS to the rescue!
>      v(s, 12);

dg(12);

It would be nice if v(s, 12) worked. Related DIP: 
https://github.com/dlang/DIPs/blob/master/DIPs/DIP1011.md

-Steve