I've been working on a script that accepts some command line parameters from the user. The first few lines in the program setup the constants I want to use in the rest of the program. 
# Because of my C++ background
use constant PROJECT => $ARGV[0];
use constant ARCHIVE => $ARGV[1];

# debuggging
print "PROJECT value = " . PROJECT . "\n";
print "ARCHIVE value = " . ARCHIVE . "\n";

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Later on in the program, I want to make a decision about the parameters, so I created the following if statment: 
     if( ARCHIVE eq "") {
          warn( "No archive file was supplied.\n");
          exit 1201;
     }

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Without specifying an ARCHIVE name, I would expect the script to die. It doesn't. So I started reading my trust Camel book on use constant. It said that constant is evaluated at compile time. That makes a lot of sense but my debug output shows: 
PROJECT value = P:\Software
ARCHIVE value =

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Why is perl able to set the PROJECT value, but can't work with the lack of an ARCHIVE value? Is this an error with my copy of Perl (ActiveState 5.6.1)?

In reply to Invalid use of constant pragma? by dhable

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