weak linking
- Subject: weak linking
- From: "Gerriet M. Denkmann" <email@hidden>
- Date: Sun, 30 Mar 2008 01:32:39 +0100
- Delivered-to: email@hidden
- Delivered-to: email@hidden
I use in some Cocoa app a weak linked library.
In some class I do:
- (BOO)haveNoLibrary
{
BOOL noHave1 = weak_function == NULL ; // does NOT work - is always NO
void *dummy = weak_function;
BOOL noHave2 = dummy == NULL ; // does work - is YES if and only
library is missing
return noHave2;
}
Why is noHave1 always NO?
Next I copied some code from the Framework Programming Guide -
Frameworks and Weak Linking:
if (weak_function == NULL)
{
NSLog(@"%s weak_function %p NULL", __FUNCTION__, weak_function );
}
else
{
NSLog(@"%s weak_function %p non-NULL", __FUNCTION__, weak_function );
}
The result without library is:
... weak_function 0x0 non-NULL
10.4.11, powerpc-apple-darwin8-gcc-4.0.1. weak_function returns void.
Kind regards,
Gerriet.
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