Chady has asked for the wisdom of the Perl Monks concerning the following question:

fellow monks, here's the set-up:

index.pl is running and at a time it will gather and eval the string:

$string = 'require ./scripts/eliza.pl';
eval "$string";

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now at eliza.pl I have this:

$|++;

use Chatbot::Eliza;

## do something with eliza...

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Now if I run this I get the following warning message:

[Sat Mar 16 21:44:55 2002] C:\Inetpub\wwwroot\index.pl: (in cleanup) C
+an't access `DESTROY' field in object of class Chatbot::Eliza : [Sat 
+Mar 16 21:44:55 2002] C:\Inetpub\wwwroot\index.pl: at ./scripts/eliza
+.pl line 34

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the problem goes away if I remove the autoflush $|++ line. Can someone explain to me why is this happening?

He who asks will be a fool for five minutes, but he who doesn't ask will remain a fool for life.

Chady | http://chady.net/

Replies are listed 'Best First'.
Re: autoflush and 'DESTROY'
by tachyon (Chancellor) on Mar 16, 2002 at 20:44 UTC

    Add the line: 

    sub DESTROY {}

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    to the Chatbot::Eliza code to fix the warning. For some background on DESTROY see Object scope and DESTROY

    From perlman:perltoot:

    Destruction happens automatically via Perl's garbage collection (GC) system, which is a quick but somewhat lazy reference-based GC system. To know what to call, Perl insists that the destructor be named DESTROY. Perl's notion of the right time to call a destructor is not well-defined currently, which is why your destructors should not rely on when they are called.

    Evidently autoflush is altering when DESTROY is called. I recall reading somewhere that you should include a DESTROY() method to avoid warnings like this but can't remember where for the life of me.

    cheers

    tachyon

    s&&rsenoyhcatreve&&&s&n.+t&"$'$`$\"$\&"&ee&&y&srve&&d&&print

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[d/l]

      to the Chatbot::Eliza code to fix the warning.

      You don't have to modify the module itself for this. Changing the module will bite you when upgrading it. 

      sub Chatbot::Eliza::DESTROY { }

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      U28geW91IGNhbiBhbGwgcm90MTMgY
W5kIHBhY2soKS4gQnV0IGRvIHlvdS
ByZWNvZ25pc2UgQmFzZTY0IHdoZW4
geW91IHNlZSBpdD8gIC0tIEp1ZXJk

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[d/l]

        Or perhaps the more obscure 

        *{Chatbot::Eliza::DESTROY} = sub {};

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        Have you considered a job with M$ ? Patching the source of the problem and informing the author is better than working around the error IMHO

        cheers

        tachyon

        s&&rsenoyhcatreve&&&s&n.+t&"$'$`$\"$\&"&ee&&y&srve&&d&&print

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[d/l]

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