Re: ivars and fundamental types
Re: ivars and fundamental types
- Subject: Re: ivars and fundamental types
- From: Dave Keck <email@hidden>
- Date: Tue, 12 Oct 2010 01:13:37 -0400
> Don't do that. object_getInstanceVariable() and object_setInstanceVariable()
> still assume the ivar is of an object pointer type.
As the documentation and prototypes stand, one would think that
object_getInstanceVariable() could be used like this:
double *doublePointer = nil;
object_getInstanceVariable(..., (void **)&doublePointer);
NSLog(@"%f", *doublePointer); // get ivar value
*doublePointer = 42.4242; // set ivar value (erroneously bypassing
potential GC write barriers if it were a pointer type)
... especially since outValue is documented as "On return, contains a
pointer to the value of the instance variable." In fact, I suppose it
should read "On return, contains the value of a pointer-typed instance
variable."
Furthermore, if object_getInstanceVariable() assumes an "object
pointer type" -- emphasis on _object_ -- shouldn't outValue be typed
{id *}?
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