Errors Using Hashes and Subroutines

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

I'm trying to become more comfortable with hashes, as well as create some toolkit code for my CGI scripts. Unfortunately, I'm running into some errors that I either don't understand or don't understand the explanations that I've found.

Consider, if you will:

#!/usr/bin/perl -wT
use strict;
$|++;

use constant ERROR_BADCONFIG => 
{ Type        => "Configuration",
  Description => "This script requires the module listed " .
                 "in the following details; please make "  .
                 "sure the module is properly installed.",
  Fatal       => 1
};

eval( "use CGI ':standard'" );
printError( $@,ERROR_BADCONFIG ) if $@;

eval( "use MIME::Lite;" );
printError( $@, ERROR_BADCONFIG ) if $@;
   
use CGI;
my $cgi = CGI->new();

print $cgi->header;
print $cgi->start_html( "Results" );
print "Configuration OK";
print $cgi->end_html;

exit 1;

sub printError
{
   my $errortext = shift;
   my ( %errorhash ) = @_;

   print "$errorhash{ 'Type' } Error Detected\n",
         "$errorhash{ 'Description' }\n",
         "Error Details: $errortext\n";
         
   if ( $errorhash{ "Fatal" } ) { die "Fatal Error Detected" };
}
[download]

As I'm sure the most experienced among you recognize that this contains a number of flaws, including the ones that Perl reports:

Reference found where even-sized list expected at errors.cgi line 42.
Use of uninitialized value in concatenation (.) at errors.cgi line 44.
Use of uninitialized value in concatenation (.) at errors.cgi line 44.

I've tried a dozen variations on the theme and have spent several hours scouring Search, Super Search, the FAQ's, the POD, and several other sources, but I'm not getting it.

Where am I going wrong? I'm trying to pass a hash and a scalar to my printError() routine (Perl 5.6.0).

Would someone mind sending this apprentice a message from the Clue server?

--f

Comment on Errors Using Hashes and Subroutines Download Code

Replies are listed 'Best First'.
Re: Errors Using Hashes and Subroutines by nardo (Friar) on Apr 17, 2001 at 23:22 UTC
ERROR_BADCONFIG is a reference. The following printError fixes your problem `sub printError { my $errortext = shift; my $errorhashref = shift; print "$errorhashref->{ 'Type' } Error Detected\n", "$errorhashref->{ 'Description' }\n", "Error Details: $errortext\n"; if ( $errorhashref->{ "Fatal" } ) { die "Fatal Error Detected" }; }` [download] Also, when you are including errors such as "Reference found where even-sized list expected at errors.cgi line 42" it is often useful to mention what line 42 is.	[reply] [d/l]

Replies are listed 'Best First'.

Re: Errors Using Hashes and Subroutines
by nardo (Friar) on Apr 17, 2001 at 23:22 UTC

sub printError
{
   my $errortext = shift;
   my $errorhashref = shift;

   print "$errorhashref->{ 'Type' } Error Detected\n",
         "$errorhashref->{ 'Description' }\n",
         "Error Details: $errortext\n";

   if ( $errorhashref->{ "Fatal" } ) { die "Fatal Error Detected" };
}
[download]

[reply]
[d/l]