Static operator overloads

[Stuart Murray]

torhu Wrote:

> Stuart Murray wrote:
> > Hi everyone
> > I'm a newbie to D and I've spent some time in the last few days messing around, seeing how things work.
> > 
> > I noticed in a news posting that you can overload operators statically..
> > i.e.
> > 
> > ///////////////
> > 
> > class Test
> > {
> > 	private char[] memstring;
> > 	
> > 	this(char[] newstring)
> > 	{
> > 		memstring = newstring.dup;
> > 	}
> > 	
> > 	char[] toString()
> > 	{
> > 		return memstring;
> > 	}
> > 	
> > 	static Test opCat(char[] newstring)
> > 	{
> > 		return new Test(newstring);
> > 	}
> > 	
> > /+
> > 	Test opCat(char[] newstring)
> > 	{
> > 		return new Test(memstring ~ newstring);
> > 	}
> > +/
> > }
> > 
> > int main(char[][] args)
> > {
> > 	Test bob = Test ~ "hello there";
> > 	writefln(bob);
> > 	return 0;
> > }
> > 
> > ////////////////
> > 
> > Browsing through the documentation I didn't come across any mention that static member operators were supported. I was just wondering if they are in fact intentional?
> > 
> > Also:
> > I notice that having 2 member functions with the same signature, one static and one not, does not work (compiler claims it a conflicts). In particular, the above case, when the non-static opCmp is uncommented it will no longer compile.
> > 
> > Is there any notes in the documentation to this effect? because I could not find any.
> > 
> > Thanks for any reply.
> > 
> 
> I haven't seen this either.  Are you sure that your static opCat 
> actually works, and is in fact static?  That compiler allows you to put 
> 'static' in several places where it has no effect.  I know that static 
> opCall makes sense for structs, but that's about it when it comes to 
> static operator overloads.  Besides, your code won't even compile, 
> because there's no default constructor.

The above compiled immediately before I pasted into my message. The only thing missing is import std.stdio.

I am fairly sure it is being used statically. Swapping the static form for the non-static form results in a compile error (because Test~"" would need to be replaced by new Test("")~""). In the section:

Test bob = Test ~ "hello";

No constructor is invoked directly, the constructor this(char[]) is used through the static opCat overload.

At least, thats how I read it.