Re: Attempt to free unreferenced scalar...

The only time I have seen this error was in doing perl Gtk programming and it was usually a result of destroying an object without destroying the embedded objects first, ie, I would destroy the top window without destroying all the widgets I had embedded in it.

When perl then went to DESTROY these objects when they went out of scope, it got very unhappy about attempting to free ( the embedded object ) an unreferenced scalar ( since the referencing object was already gone ).

I am not claiming this isn't a bug, nor am I claiming this is your problem. I am merely offering my past experience hoping it may help.

Mik
mikfire

Comment on Re: Attempt to free unreferenced scalar...

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Re^2: Attempt to free unreferenced scalar... by Anonymous Monk on Sep 22, 2010 at 23:35 UTC
I was getting this bug today and none of the pages I read helped so I figured I should post now that I figured out the problem. All pages I read indicate it's probably a perl bug itself. But for me it was due to having a foreach loop like this: foreach $key (keys %hash) { } with another foreach loop inside using the same variable name and same hash foreach $key (keys %hash) { foreach $key (keys %hash) { } } Incidentally, this only caused the problem in strict mode. I'm not saying this simple loop would replicate the problem, I got it down to about 20 lines and still throwing the error. But if you're getting this error message, look for a nested thing like that, it might be what's causing it. Perl should maybe throw a warning when a loops are nested like that with the same variables, because otherwie it was pretty hard to track down in my 1000 line program, I had to remove piece by piece until it became evident.	[reply]

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Re^2: Attempt to free unreferenced scalar...
by Anonymous Monk on Sep 22, 2010 at 23:35 UTC

foreach $key (keys %hash) {

}

with another foreach loop inside using the same variable name and same hash

foreach $key (keys %hash) {
foreach $key (keys %hash) {

}
}

Incidentally, this only caused the problem in strict mode. I'm not saying this simple loop would replicate the problem, I got it down to about 20 lines and still throwing the error. But if you're getting this error message, look for a nested thing like that, it might be what's causing it. Perl should maybe throw a warning when a loops are nested like that with the same variables, because otherwie it was pretty hard to track down in my 1000 line program, I had to remove piece by piece until it became evident.

[reply]