Re: Derived properties
Re: Derived properties
- Subject: Re: Derived properties
- From: Greg Parker <email@hidden>
- Date: Wed, 11 Nov 2009 12:31:24 -0800
On Nov 11, 2009, at 11:52 AM, Christian Ziegler wrote:
> In order to reuse code I find it often very handy to write little "getters" which don't get their return value from an ivar but compute it somehow. I believe this is called derived property since it derives its value from other properties. My question is, what is the best style implementing such derived properties. With dot-notation in mind, I think the options are:
>
> 1. Only write the "getter"-method, no property, no sythesize, DON'T use dot-notation
> 2. Only write the "getter"-method, no property, no sythesize, DO use dot-notation
> 3. Write "getter"-method, write property (readonly, to justify dot-notation), sythesize
>
> A basic question here is, for any method which might as well be a property and of course doesn't have any parameters, is it ok to use dot-notation or should'nt you do that.
>
> Simple example:
>
> - (BOOL)itemsSelected {
> return [myTableView selectedRow] != -1;
> }
4. Write a getter method, @property(readonly), and no @synthesize. Use dot notation if you like.
There's no need to @synthesize since you are providing the entire property implementation (the getter method) yourself.
One reason to make it a proper @property is that Xcode's autocompletion of dot notation only looks at @properties, not methods. So `obj.i` will autocomplete to `obj.itemsSelected` only if there is an @property itemsSelected.
--
Greg Parker email@hidden Runtime Wrangler
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