Re: [Vala] Operator overloading

["A. Walton" <awalton gnome org>]

2009/3/23 James Cox <jamescox84 googlemail com>:
> I personally think operator overloading is a good feature, and that the only
> arguments for and against it are personal preference.  There is no technical
> reason not to include them, allowing those who like and understand operator
> overloading to use the feature.

There's an enormous technical reason. One of Vala's main goals is to
write libraries. Operator overloading means public symbols with
mangled names, which are virtually unusable from C (and thusly, any
other language save Vala). You could help this by mangling them with a
transform like operator+()->_add(), but then you run the obvious risk
of symbols colliding and making the C api completely unusable.

(All of that, and I'd love to see the Vala-style generated C code for
doing a complex math operation on a vector complete with Vala's
copious use of side effects... man that would be nasty. :)

> I think it would be a shame not to
> implement them just because we were scare of what some programmers might do
> with them.

This is a very common software design problem, and it has been solved
time and time again, usually the same way: If there are more occasions
to use a feature incorrectly than correctly, you should opt on the
side of leaving that feature out whenever possible.

The only valid use case presented in this thread has been to reduce
typing in the case of vector types, and the counter-cases of it being
used incorrectly are staggering (just read any C++ library horror
story, they usually start with either templates or
operator-overloading, or for the very unfortunate, both). This also
includes C#/Vala's own usage of overloading with anonymous functions;
unfortunately it can't realistically be fixed in Vala since it's
trying to stay somewhat C#-like.

Besides, any good IDE/editor with autocomplete can help reduce the
typing for you in the non-overloaded case.

-A. Walton

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