Hi Armin, On Mon, 30 Aug 2004, Armin Rigo wrote:

Hi Richard,

On Sat, Aug 28, 2004 at 10:22:31PM +0100, Richard Emslie wrote:

...

Also BTW you can't overload c++ return types - unless you know something I don't.

That's right, but it's not necessary. The C version (genc.h) has a type code for return type too (e.g. OP_ADD_iii) but that's only so that typer.py can know what the return type will be, and convert it if needed. In general I don't think we need to overload on the return type. If we define only:

Int op_add(const Int&, const Int&) Ref op_add(const Ref&, const Ref&)

and then do:

someref = op_add(someint, someint)

then the first signature will be choosen and the return type will be automatically converted from Int to Ref, which is fine.

I get it (partially). :-). Either we only support ops which explicitly match the signature and convert the return type via a temporary or not-so-obviously let c++ create a temporary when passing in a const c++ reference (c++ : why??? if it wasn't reference then fair enuf... but *sigh*). """ Int i; Ref r; r = op_add(i, i); // calls Int op_add(const Int&, const Int&) // converts return type :-) r = op_add(i, r); // i converted to Ref as temporary :-( """ but I assume the latter is not what you mean. Actually, to make things more explicit - I would prefer to only have an assignment operator for Ref: class Ref... { ... Ref & operator= (const Int &ref) { ... return *this; } } Cheers, Richard