Re: KVO and accessors - are they needed
Re: KVO and accessors - are they needed
- Subject: Re: KVO and accessors - are they needed
- From: "John C. Randolph" <email@hidden>
- Date: Fri, 22 Oct 2004 12:52:53 -0700
On Oct 22, 2004, at 9:21 AM, Steven Kramer wrote:
Well, YMMV of course, but Keep in mind that when KVC has to go
looking for your ivars, it has to do a bunch of wading through the
Obj-C runtime that isn't necessary if you provide accessor methods.
But the same more or less holds for method lookups, doesn't it?
Not really.
When you send a message for the first time to an instance of a given
class, it may have to recurse through the inherited method tables to
find the implementation, but it only has to do so once. After that
though, it will be in the method cache.
If you let KVC hunt for your ivars, it has to do so every time. I
haven't measured it, but since an accessor method can determine the
offset to the ivars it affects at compile time, it's going to be a lot
faster.
Now, you could argue that writing accessors is a premature
optimization, but since there are tools to autmatically generate
accessor methods, you might as well use them.
-jcr
John C. Randolph <email@hidden> (408) 974-8819
Sr. Cocoa Software Engineer,
Apple Worldwide Developer Relations
http://developer.apple.com/cocoa/index.html
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