Re: DIP80: phobos additions

[Tofu Ninja via Digitalmars-d]

On Wednesday, 24 June 2015 at 19:04:38 UTC, Wyatt wrote:
On Wednesday, 17 June 2015 at 09:28:00 UTC, Tofu Ninja wrote:

I actually thought about it more, and D does have a bunch of 
binary operators that no ones uses. You can make all sorts of 
weird operators like +*, *~, +++, ---, *--, /++, ~~, ~-, -~,
>>>--, &++, ^^+, in++, |-, %~, ect...

void main(string[] args){
        test a;
        test b;
        a +* b;
}
struct test{
        private struct testAlpha{
                test payload;
        }
        testAlpha opUnary(string s : "*")(){
                return testAlpha(this);
        }
        void opBinary(string op : "+")(test rhs){
                writeln("+");
        }
        void opBinary(string op : "+")(testAlpha rhs){
                writeln("+*");
        }
}

Oh right, meant to respond to this.  I'll admit it took me a 
few to really get why that works-- it's fairly clever and 
moderately terrifying.  (I showed it to a friend and he opined 
it may violate the grammar.)

But playing with it a bit...well, it's very cumbersome having 
to do these overload gymnastics.  It eats away at your opUnary 
space because of the need for private proxy types, and each one 
needs an opBinary defined to support  it explicitly.  It also 
means you can't make overloads for mismatched types or builtin 
types (at least, I couldn't figure out how in the few minutes I 
spent poking it over lunch).

-Wyatt

I am thinking of writing a mixin that will set up the proxy for 
you so that you can just write.

struct test
{
     mixin binOpProxy("*");
     void opBinary(string op : "+*", T)(T rhs){
          writeln("+*");
     }
}

The hard part will be to get it to work with arbitrarily long 
unary proxies. Eg:
mixin binOpProxy("~-~");
void opBinary(string op : "+~-~", T)(T rhs){
     writeln("+~-~");
}