CGI... uninitialized value... which variables?

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

Quick question, if I may:

CGI script. Perl 5.6.x

I get errors such as Use of uninitialized value in concatenation (.) or string at /blah/mycode.pm line 488. When I look at the line it has maybe 5 variables listed on it. Is there a way to get it to tell me which are not initialised?

I'd rather make the minimum changes - I just want to know the names of the symbols...

Thanks... M.

Thanks for the answers: Just to clarify - anytime that error occurs, no matter where, I want to know the variable name. Sure I can do prints, etc, around a particular instance but I'd rather change the error reporting system.

Comment on CGI... uninitialized value... which variables?

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Re: CGI... uninitialized value... which variables? by Roger (Parson) on Sep 29, 2004 at 11:59 UTC
You could use the Data::Dumper module. `use Data::Dumper; ... my ($a, $b, $c, $d); $a = 1; $b = 2; $d = 4; print Dumper([ $a, $b, $c, $d ]);` [download] And check for variable with 'undef' value...	[reply] [d/l]
Re^2: CGI... uninitialized value... which variables? by mrjcleaver (Initiate) on Sep 29, 2004 at 14:34 UTC
Thanks... see above - am looking for a generic solution	[reply]
Re: CGI... uninitialized value... which variables? by amt (Monk) on Sep 29, 2004 at 13:05 UTC
If you are looking to debug, you can add this block: `print '$var1' unless($var1); print '$var2' unless($var2);` [download] amt. perlcheat	[reply] [d/l]
Re^2: CGI... uninitialized value... which variables? by mrjcleaver (Initiate) on Sep 29, 2004 at 14:36 UTC
Thanks... see above - am looking for a generic solution...	[reply]
Re: CGI... uninitialized value... which variables? by kutsu (Priest) on Sep 29, 2004 at 16:49 UTC
For the varies errors and warnings I get from CGI, I like to have a semi-generic module I can call to print to a logfile with the basic information (variable data, short descriptive error message, time/date, line number, some error code/variable to send to HTML::Template (for the user to see), and etc. Note this will not replace Data::Dumper for debugging errors nor die for serious errors, but is very helpful for errors like a param being empty or invalid (esp. if it is in a sub that you can call like this: `error() unless defined $someparam;`). Just my way of doing things. "Cogito cogito ergo cogito sum - I think that I think, therefore I think that I am." Ambrose Bierce	[reply] [d/l]
Re^2: CGI... uninitialized value... which variables? by mrjcleaver (Initiate) on Sep 30, 2004 at 09:55 UTC
Thanks. Do you have a mechanism to make it get called during die? That would be a great way of getting CGI to spit out the context information needed to make sense of why trouble had occurred. Is the code available anywhere?	[reply]