On Thu, May 22, 2008 at 1:34 PM, Peter Zegelin
<email@hidden> wrote:
On 22/05/2008, at 3:15 PM, mmalc crawford wrote:
On May 21, 2008, at 9:48 PM, Peter Zegelin wrote:
So my question is - is there a way to include the first label? I note
that the examples in the ObjectiveC manual seem to leave the first one out
also:
[myRect setWidth:10.0 :15.0]; ---> [myRect setWidth:10.0 height:15.0];
No, it doesn't.
[myRect setOrigin:30.0 :50.0];
Here the method name, setOrigin::, has two colons, one for each of its
arguments. The arguments are inserted after the colons. This method name
uses unlabeled arguments. Unlabeled arguments make it difficult to determine
the kind and purpose of a method's arguments. Instead, method names should
include labels describing each of their arguments. Argument labels precede
each colon in the method name. The setWidth:height: method, for example,
makes the purpose of its two arguments clear:
[myRect setWidth:10.0 height:15.0];
<http://developer.apple.com/documentation/Cocoa/Conceptual/ObjectiveC/Articles/chapter_2_section_3.html>
mmalc
Well now I'm a bit confused as I just used the same paragraph to show that
it does. Too much C++ thinking I guess. I'm thinking the method name is
setWidth with two arguments, one unlabeled and the other labeled with
'height'. Any suggestions where I should brush up on this - apart from the
manual I'm looking at already?
You're misunderstanding the docs here. It doesn't say that the two are
equivalent. Rather it says that the two are *similar*, and that the
latter is preferred because it's more verbose.
In C++, you might compare these two function names:
DoSomething()
DoSomethingWithString()
The latter gives you more information about what the function does and
what kind of parameter it takes. Even though they share a common
prefix, the compiler considers them to be unrelated. The relationship
is only for the human.
Likewise in Objective-C, the method name is the *entire* thing,
"labels" and all, so these are all different methods:
-doSomething (no parameters)
-doSomething: (one parameter)
-doSomething:withString: (two parameters)
-doSomething:withString:andInteger: (three parameters)
-doSomething:andInteger:withString: (three parameters)
-doSomething:: (two parameters)
More properly, the arguments aren't labeled, but rather they are
interleaved with the method name. This is why the whole thing is
significant, and you can't just change the order around and still
refer to the same method.
Mike
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