[cairo] Re: cairo c++ bindings

[Bill Spitzak]

Murray Cumming wrote:

> An if(somebool) will not add a significatn amount of run-time overhead.
> I'd be happy to add a Cairo::set_ignore_errors(bool) function.

Actually it will if the code is inlined, as it can add significant size 
to the code and thus make things not fit in caches. A quick test reveals 
that this triples the size of the inlined code (for a phony test with 
one argument passed to the other function).

A more serious problem is that inlinining a single function call is an 
obvious win in speed (no matter how tiny) and the same size in code. But 
a function that has an if and a call, it is impossible to be certain 
which is better. It would be preferrable that the C++ wrapper be 
unquestionable for the majority of Cairo calls.

My preference would be for the C++ wrapper to not test anything or throw 
any exceptions, and to just wrap the "test status" call like every other 
Cairo interface. Calling code can do "if (cairo_c->error()) throw 
exception;"

The ideas mentioned below for using templates to make a different class 
that does throw exceptions may be a good idea, though, as long as the 
header files are still readable.