Subject: Re: clarification regarding properties
On Mar 27, 2009, at 09:24, WT wrote:
If I understand correctly, there *is* a difference between using
self.foo and just foo, where foo is a property, right?
foo = whatever
just sets the value of foo to the value of whatever, but
self.foo = whatever
actually calls the method setFoo: with whatever as its argument.
This difference is important because the setter method might do some
necessary memory management which the simple unqualified assignment
Is my understanding correct?
You got a "correct" response, and I'm going to add an "incorrect"
The 'foo' in 'self.foo' is a property. The 'foo' in 'just foo' is
*not* a property, but an instance variable. It's really important to
know that the two are entirely different things, even when they are
named the same. Whether the property foo even uses an instance
variable foo is an implementation detail of your class. A property
*may* be implemented using an instance variable for its storage
requirements, and the instance variable *may* have the same name as
the property, but neither of those things are requirements.
Incidentally, the syntactic equivalent of Java's 'this.foo' is
probably Objective-C's 'self->foo', which *is* is the same thing as
just plain 'foo'. Any resemblance between 'this.foo' and 'self.foo'
is an optical illusion. ;)
Incidentally (again), I believe the current recommendation is
generally *not* to use property accessors (setters and getters) inside
initializers (init... methods) and dealloc methods. But that seems to
be a somewhat hot topic, so you might see differing opinions on it.
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