Re: Understanding the "declaration of instance variables in the interface is deprecated" warning.
Re: Understanding the "declaration of instance variables in the interface is deprecated" warning.
- Subject: Re: Understanding the "declaration of instance variables in the interface is deprecated" warning.
- From: Bernard Desgraupes <email@hidden>
- Date: Wed, 03 Jun 2015 17:27:04 +0200
What about the @property declarations in the new scheme ?
Le 3 juin 2015 à 17:15, Mark Wright <email@hidden> a écrit :
> Sorry, yes, I misread the initial paragraph that mentions the @implementation block. I actually meant implementation *file* since that’s typically where the class extension @interface is declared (it extends the class internally).
>
> However, as you’ve surmised, all this talk of clang warnings regarding this is directly related to the primary *class interface* which is typically declared in the header file. This is the class interface:
>
> @interface SubClass : ParentClass
> ….
> @end
>
> The idea is to end the old ways of declaring ivars in the header and move them into the implementation where they belong (they’re private to the class).
>
>
>
>
>> On 03 Jun 2015, at 16:02, Alex Zavatone <email@hidden> wrote:
>>
>>
>> On Jun 3, 2015, at 10:41 AM, David Duncan wrote:
>>
>>> There are 3 ways to add ivars to a class. The traditional way:
>>>
>>> @interface Foo {
>>> id _bar;
>>> }
>>>
>>> And 2 new ways:
>>>
>>> @interface Foo() { // Class extension, note the ()
>>> id _baz;
>>> }
>>
>> Ahhhhhhh. Completely missed that. Haven't seen it explained that clearly in a morning of surfing.
>>
>> So, running a quick test using the clang pragma for -Wobjc-interface-ivars, in both the .h and .m files of a class this clarifies the Apple and Clang documentation quite a bit.
>>
>> In the 3 cases you outlined for declaring iVars, Clang ONLY warns about declaring the ivars within the @interface parens of @interface which is generally within the header file.
>>
>> Both other cases (the two new ways of class extension, @interface stuff() {} and @implementation stuff {} ) do not upset Clang at all.
>>
>> So, generally, the rule comes down to "don't declare ivars within the @interface that is probably within your .h file but if you need to (you should use properties instead), you can within the class extension and @implementation."
>>
>> Does this sound like a proper explanation?
>>
>> Thanks much, David.
>>
>>
>>> @implementation Foo { // Implementation block.
>>> id _faz;
>>> }
>>>
>>
>>
>>>> On Jun 3, 2015, at 7:32 AM, Alex Zavatone <email@hidden> wrote:
>>>>
>>>> Maybe I should have included the text above it.
>>>>
>>>> "It's also possible to use a class extension to add custom instance variables. These are declared inside braces in the class extension interface."
>>>>
>>>> So, I don't know how you see that it goes in the @implementation block since the code I pasted and the line above it say it goes in the @interface.
>>>>
>>>> Page 73 of
>>>> https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/ProgrammingWithObjectiveC/ProgrammingWithObjectiveC.pdf
>>>>
>>>> On Jun 3, 2015, at 10:22 AM, Mark Wright wrote:
>>>>
>>>>> That’s a ‘Class Extension’. Furthermore, it’s under the title "Class Extensions Extend the Internal Implementation”. It also mentions that it goes in the @implementation block…
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>> On 03 Jun 2015, at 15:11, Alex Zavatone <email@hidden> wrote:
>>>>>>
>>>>>> Apple's Programming with Objective-C reference document © 2014
>>>>>>
>>>>>> https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/ProgrammingWithObjectiveC/ProgrammingWithObjectiveC.pdf
>>>>>>
>>>>>>
>>>>>> Page 73
>>>>>>
>>>>>> @interface XYZPerson () {
>>>>>> id _someCustomInstanceVariable;
>>>>>> }
>>>>>> ...
>>>>>> @end
>>>>>>
>>>>>> Uhhhhhh.
>>>>>>
>>>>>> Doesn't this violate Clang's own mention that "declaration of instance variables in the interface is deprecated" in Apple's own recommendations and documentation?
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>>>>>
>>>>
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>>>
>>> --
>>> David Duncan
>>>
>>
>
>
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