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Re: Exception when using GSDictionary in corebase
From: |
Dr. H. Nikolaus Schaller |
Subject: |
Re: Exception when using GSDictionary in corebase |
Date: |
Fri, 20 May 2011 19:44:06 +0200 |
Am 20.05.2011 um 19:13 schrieb David Chisnall:
> On 20 May 2011, at 17:20, Dr. H. Nikolaus Schaller wrote:
>
>> Why aren't you using a NSArray/CFArray to simulate a NSSet? They are much
>> more similar than
>> dictionaries and sets.
>
>
> Not really. A dictionary is just a set of pairs, where equality is defined
> by comparing just the first elements of the pairs. An array is an ordered
> collection where an elements can occur multiple times. A set is an unordered
> collection where elements may occur at most once. They have very little in
> common.
It is easy to use an array like a set by:
a) ignoring that an array has an index
b) and just checking if a new value is already stored to avoid duplicates.
Both have a count, can be enumerated, copied, extended by new objects, checked
if some object is contained.
I.e. exactly 2 differences and at least 5 commonalities... Makes at least 71%
similarity :)
One can live wihout NSSet, but you can't without NSArray and NSDictionary...