🚀 go-pugleaf

maxtal@extro.ucc.su.OZ.AU (John MAX Skaller) writes:

>I would like to propose that if a class has virtual functions,
>then any destructor generated by the compiler will be virtual
>by default.
>
>Advantages: much safer, ensures correct deletion of objects
>by default.  Removes a source of bugs. Removes the reminder
>that its wise to do this from the FAQ.
>
>Disadvantage: might slow down destruction a little. Can be
>fixed by the programmer explicitly declaring a non-virtual
>destructor.

I think that this situation should cause a compiler warning, rather
than adding another arbitrary rule in the language for programmers to
remember. Bugs would still occur if a programmer accidentally forgot to
make the destructor virtual. A good compiler will generate a warning
in this situation anyway (eg. g++ does, I believe).

Mind you, I do believe that there is a place in the standard for
required warnings. Claims that these are a "quality of implementation"
issue ignore the social effect of standards. There are never *any*
genuinely 100% conformant compilers, no matter what it says on the
box you bought it in. (Read the fine print on the license inside :-( ). 
The truth is that standards provide a strong incentive for compiler
vendors to ship products with certain characteristics. Provided (as
with all other aspects of a standard) that they don't require an
excessive difficulty of implementation, I don't see any good reason
not to include particular required warnings as part of a standard.

[Off the topic, another situation that should have a required warning
is the (void *) to (T *) conversion. It is definitely a hole in the
type system, but making such conversion *illegal* breaks many C programs.
It broke ALL of my C programs (well, ok, except for the hello world ones :-).
A warning would have closed the hole in the type system just as well -
after all, programmers can always achieve the same effect with a cast,
so it doesn't actually "close" the hole anyway - the error message is
just like a warning, except that you have to actually modify the
program text to get it to compile.]

-- 
Fergus Henderson             fjh@munta.cs.mu.OZ.AU      
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