Little demo of allowing basic types to implement interfaces.

[Rory McGuire]

On Wednesday, 4 September 2013 at 00:56:55 UTC, Rory McGuire 
wrote:
> I was wondering if its possible to do interfaces the way 
> #golang does it
> but in #dlang.
>
> Here is my first try: https://gist.github.com/rjmcguire/6431542.
>  Any help on making this smaller would be awesome.
>
> Cheers,
> R

Here is another example use, checking if a type can convert 
itself to ubyte[]:
void main() {
	int i = 0x34342343;
	writebytes(i);
}

interface IRawBytes { ubyte[] bytes(); }
void writebytes(T)(T item) if (Implements!(T, IRawBytes)) {
	import std.stdio : writeln;
	writeln(item.bytes);
}
ubyte[] bytes(ref int i) {
	ubyte* ptr;
	ptr = cast(ubyte*)&i;
	return ptr[0..i.sizeof];
}


In the above example you get a nice error message if int does not 
have the "bytes" ufcs function.

missing: ubyte[] int.bytes()
int, does not implement interface: traits.IRawBytes
traits.d(18): Error: template traits.writebytes does not match 
any function template declaration. Candidates are:
...