Re: Alloc/dealloc etiquette

[Sherm Pendley]

Michael Ash <mike@mikeash.com> writes:

> Override -dealloc if you have any instance variables pointing to objects 
> that you own. This all comes down to memory management; if at some point 
> you allocated, copied, or retained an object and put it in an instance 
> variablel, you should release it here.

A minor nit - I prefer to release instance variables (if they're objects)
in their accessor methods. One common way to do this is with the accessors
that can be automatically generated by Xcode:

    - (void)setFoo:(NSObject *)value {
        if (foo != value) {
            [foo release];
            foo = [value copy];
        }
    }

There are many variations on this theme of course - and at least one utility
(Accessorizer) to help manage them all. What they all share though, is the
goal of placing the retention action (a -copy in this case) in the same place
as its matching release. It's a simple pattern; if you want to refer to some-
thing later, you store a reference to it using an accessor. The accessor will,
at the same time, take care of releasing any previous references if needed.

A great deal of confusion seems to come out of not using this pattern, and
scattering memory management code everywhere - often seemingly at random -
instead.

To support this pattern, I don't use -release in -dealloc. Instead, I'd use
the accessor there as well:

    [self setFoo:nil];

sherm--

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