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Re: objc_exception_throw


El 30/06/2008, a las 0:11, Chris Espinosa escribió:

On Jun 29, 2008, at 12:53 PM, Jens Alfke <email@hidden> wrote:


On 29 Jun '08, at 12:20 PM, Joan Lluch (casa) wrote:

By setting a Breakpoint at objc_exception_throw or [NSException raise] I am able to stop my program when (for example) an out of range exception is thrown. However the call stack trace on the debugger window or the 'bt' command only shows a single line. For example:

I've also had this happen occasionally with various breakpoints (not just objc_exception_throw); I'm not sure what causes it or how to prevent it.

Is this in a debug or a release build of your app? Optimized code can sometimes lead to confused backtraces, although it should never get this bad.

A common cause of a truncated backtrace on exception handling is if your function somehow corrupted the return stack, which may also have caused the exception in the first place.  A buffer overrun or bad cast on a function local is a common cause of this.

Chris

Thanks to all for your replies. I actually have all sorts of problems related to the call stack with the debugger, for example the step over command usually does not work, and it performs a step into instead. This is annoying because it turns de debugger completely useless, without the ability to see the stack trace or to run the app step by step.

I am using XCode 3.0 and yes, I compile the app as debug with compiler optimisation turned off and debug symbols generation enabled. I start to get frustrated about it because I don't get it. 

The exception that is thrown is a simple out of range access to an NSArray, which does not crash or hangs the app, so I am still more confused about it.  I tend to think that the problem must be related to some misconfiguration of XCode or the debugger. By setting lots of breakpoints in my app I figured out that the origin of the problem is in the observeValueForKeyPath method of one of my controller objects, but again, breakpoints set in that method do not show any stack trace at all. Please help !

Joan Lluch.
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References: 
 >objc_exception_throw (From: "Joan Lluch (casa)" <email@hidden>)
 >Re: objc_exception_throw (From: Jens Alfke <email@hidden>)
 >Re: objc_exception_throw (From: Chris Espinosa <email@hidden>)



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