Re: 'selector not recognized' ?
Re: 'selector not recognized' ?
- Subject: Re: 'selector not recognized' ?
- From: Shawn Erickson <email@hidden>
- Date: Thu, 22 Jul 2004 11:08:40 -0700
On Jul 22, 2004, at 10:20 AM, Fritz Anderson wrote:
NSView * myParent = [self superview];
// Do things with myParent
// Stop doing things with myParent
NSString * scratch;
[scanner scanString: @"foo" intoString: &scratch];
Both myParent and scratch will appear in the debugger's list of local
variables, even though the same storage (or, likelier, register) is
allocated to both. The debugger, being whizzy, tries to display the
string value of scratch. But in the early part of the function, that
register is filled with a pointer to an NSView, which doesn't respond
to messages like "length". Whereupon the debugger belches loudly (***
-[NSView length]: selector not recognized) and refuses to be useful
any more.
In an unoptimized executable (not compiler optimized) while in the same
block of code myParent and scratch variables will be held in different
memory slots on the stack, they will not share the same storage (even
in optimized code they likely will be held in different slots).
Now both myParent and scratch pointers could point to the same location
in memory either because on isn't initialized, explicit assignment, or
the memory location they point at got reused.
I personally have not seen, at least noticed, the debugger issue you
outline above when debugging an unoptimized executables but if it
exists and prevents further use of the debugger in that session make
sure to file a defect about it.
-Shawn
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