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Re: Are these the same and correct?
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Re: Are these the same and correct?


  • Subject: Re: Are these the same and correct?
  • From: Chris Hanson <email@hidden>
  • Date: Mon, 14 Nov 2005 12:10:02 -0800

On Nov 14, 2005, at 11:42 AM, Sherm Pendley wrote:

But, as a matter of internal implementation details, there's no guarantee that n is autoreleased in the second case, although it quite often will be.

In the second case, you must always treat the object pointed to by "n" as autoreleased

No, you treat it as something for which you are not responsible. It might be autoreleased, it might be a constant, a singleton, or whatever - that's an implementation detail you don't need to worry about. The sole guarantee is that you don't have to release it.


"Doesn't have to be released" != "Guaranteed to be autoreleased".

There is more than just the guarantee that the developer doesn't have to release the object.


There is also the guarantee that the developer cannot rely on the the object's existence beyond the scope of the autorelease pool in which it was allocated, unless the developer explicitly retains it.

This is something that trips up people new to Cocoa. Your initial phrasing could lead people to try to "figure out" whether certain objects are autoreleased before retaining and releasing them, when in fact they always need to write their code as if these objects are autoreleased.

  -- Chris

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References: 
 >Are these the same and correct? (From: "Brian O'Brien" <email@hidden>)
 >Re: Are these the same and correct? (From: Sherm Pendley <email@hidden>)
 >Re: Are these the same and correct? (From: Chris Hanson <email@hidden>)
 >Re: Are these the same and correct? (From: Sherm Pendley <email@hidden>)

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