Re: A Question on estimating +arrayWithCapacity
Re: A Question on estimating +arrayWithCapacity
- Subject: Re: A Question on estimating +arrayWithCapacity
- From: mmalc Crawford <email@hidden>
- Date: Fri, 09 Jan 2009 17:45:22 -0800
On Jan 9, 2009, at 5:40 PM, Graham Cox wrote:
On 10 Jan 2009, at 12:27 pm, Kyle Sluder wrote:
Part of the problem that was addressed in the previous thread was
that
+array is not documented to actually give you a mutable instance.
While in practice it works fine, there's no guarantee.
Isn't guaranteed by the semantics of inheritance? I've specified the
class: [NSMutableArray ... and what I want it to give me... array];
And the fact that NSMutableArray inherits NSArray ensures that
anything that array can do, NSMutableArray can do.
"The return type of an initializer method should be id.
The reason for this is that id gives an indication that the class is
purposefully not considered—that the class is unspecified and subject
to change, depending on context of invocation. For example, NSString
provides a method initWithFormat:. When sent to an instance of
NSMutableString (a subclass of NSString), however, the message returns
an instance ofNSMutableString, not NSString."
<http://developer.apple.com/documentation/Cocoa/Conceptual/ObjectiveC/Articles/chapter_4_section_4.html#//apple_ref/doc/uid/TP30001163-CH22-SW4
>
mmalc
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