Re: GC, plain C structs, and when to use __strong
Re: GC, plain C structs, and when to use __strong
- Subject: Re: GC, plain C structs, and when to use __strong
- From: Quincey Morris <email@hidden>
- Date: Tue, 21 Sep 2010 16:13:13 -0700
On Sep 21, 2010, at 15:37, Sean McBride wrote:
> If I have a plain C struct that contains some Obj-C object pointers like:
>
> struct {
> int boring;
> NSString* string;
> } MyStruct
>
> What must I do to be safe in GC?
>
> a) I know I must allocate my structs using NSAllocateCollectable and
> NSScannedOption.
> b) I'm pretty sure I don't need a '__strong' in my struct declaration.
> (doc say "__strong is implicitly part of any declaration of an Objective-
> C object reference type.")
> c) I'm pretty sure if I use a pointer to this struct as an ivar, I must
> tag it with __strong.
At risk of getting myself into trouble, I'd say correct, correct and correct.
> d) I'm not sure about passing pointers to this struct around. Need I
> tag all parameters and return values as __strong too? ex:
>
> void DoThing (__strong MyStruct* param) { ... }
At ditto risk, I'd say no to '__strong'. Variable 'param' is a stack variable is therefore a *root* reference, and as such the concept of strong or weak doesn't apply. (That is, AFAIK, applying '__strong' or '__weak' to a stack variable *never* has any effect on its behavior in any way.)_______________________________________________
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