http://d.puremagic.com/issues/show_bug.cgi?id=5893
Summary: Allow simple aliases for operator overloading Product: D Version: D2 Platform: All OS/Version: All Status: NEW Severity: enhancement Priority: P2 Component: DMD AssignedTo: nob...@puremagic.com ReportedBy: schvei...@yahoo.com --- Comment #0 from Steven Schveighoffer <schvei...@yahoo.com> 2011-04-26 13:04:35 PDT --- If you wish to use virtual operators in D classes, the current thinking is you would wrap a virtual function with a template function that handles the operator. This means you have to implement a template function, taking care to use the same arguments that the other function will require, and using the proper return type as well. I thought of an alternative way to do this that makes wrapping virtual functions super-easy. However, the compiler rejects it (for a strange reason). class C { void concatAssign(C other) { } void concatAssign(int other) { } // to demonstrate overloading template opOpAssign(string s) if (s == "~=") // line 6 { alias concatAssign opOpAssign; } } void main() { auto c = new C; c.opOpAssign!"~="(c); // works c.opOpAssign!"~="(1); // works c ~= 1; // line 15 } testaliasvirt.d(6): Error: template testaliasvirt.C.opOpAssign(string s) if (s == "~=") is not a function template testaliasvirt.d(15): Error: cannot append type int to type testaliasvirt.C I think the compiler should accept this code. In fact, I thought the compiler just rewrote ~= to .opOpAssign!"~=". The error message seems to suggest it does some unnecessary checking to make sure it's a function template. If it did work, this method provides not only a very efficient and backwards compatible way to do operators (no wrapper code is generated/called, no relying on inlining to make sure performance isn't hurt), but one could easily create a single mixin that forwarded all operators to the old style operators (if you didn't want to do it manually like I have). You don't even need to deal with forwarding parameters (the biggest pain of auto-wrapping functions)! I can see this being of use for opDispatch as well. Note that bug 4182 would have to be fixed for true backward compatibility (i.e. forwarding covariance with the virtual operators). But that technically is a separate issue, not a blocker. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------