Re: Q: Unused local variables

[Benoît Minisini <benoit.minisini@xxxxxxxxxxxxxxxx>]

Le 12/08/2026 à 09:10, BB a écrit :
> Does having unused local variables in a method actually have an effect?
>
> I've never worried about it until today. My theory is that the only 
> effect would be the execution of the command to allocate some space on 
> the local heap when the method is activated, which would then be freed 
> when the method exits. That is, approximately 1 malloc and 1 free.
>
> But is this what actually happens? Or since the variable is unused is 
> the compiler smart enough to ignore it altogether?
>
> regards
>
> b

If your unused variables are not initialized at all, then they just take 
a stack slot.

And there is no malloc() / free() involved in stack allocation.

In Gambas, the entire stack is allocated by a memory mapping of its 
maximum size ("man mmap"). That means that the memory is only actually 
allocated at first use, i.e. as the stack is growing (at least on Linux).

I admit that the compiler could ignore unused local variables so that 
nothing is allocated at all. But he is dumb. :-)

Regards,

--
Benoît Minisini.