Note, you would be doing all this on one such query object.

Let me try to clarify what LadyD is talking about. The script is a state machine style CGI. In some states she needs to get data in and out of a text file.

Simple, I thought, just use Data::Dumper to get strings to write out and then read and eval them to get them back. LadyD decided to read the CGI docs and found the CGI::save method which saves form input to a filehandle. The data can be retrieved when you create a new CGI object by saying $q = new CGI (FILEHANDLE). The problem is that by the time she knows which file to open, she has already had to use info from the CGI object.

I suggested she do something like this:

use CGI;
use strict;

my $q = new CGI;

if ($q->param('state') eq 'foo')
{ DoFoo($q);
} else
{ ErrorOut('Say what?') }

sub DoFoo
{   my $q = shift;
    # do some magic to pick filehandle
    open (FILEHANDLE, "<the_file") or die "Sadness: $!\n";
    my $p = new CGI ('FILEHANDLE');

    foreach ($p->param())
    {   # $q->param($_) = $p->param($_) Bad old code
        # I sure whish I could do that sort of thing, I make this erro
+r too often.
        $q->param( -name=>$_, -values=>$p->param($_) );
    }

    # do more stuff
}
sub ErrorOut
{  die shift;
}
[download]

Please note that this code is totally untested off the top of my head type material. The important bit is in the DoFoo subroutine, especially the for loop.

So, is it bad to have two CGI objects in one script? Should she just use Data::Dumper like everyone else? Should I just butt out?

Updated I fix my bad code. $q->param($_) = $p->param($_) should be $q->param( -name=>$_, -values=>$p->param($_) );

TGI says moo

#!/usr/bin/perl -Tw
use CGI;
my $cgi = new CGI;

# show current list 
print "\n\n";
print join(" ",$cgi->Vars());
print "\n";
 
if (open(FILE, "<./saved_params.txt")) {
  # add saved parameters
  while(<FILE>) {
    chomp;
    # CGI's save() ends the file 
    #  with = alone on the last line    
    last if $_ =~ /^=$/; 

    # split out the key=value pair
    my($key, $val) = split(/=/,$_,2);

    # and add them to the current list
    $cgi->param($key=>$val);
  }
}
 
# show final list
print "--\n";
print join(" ",$cgi->Vars());
print "\n\n";
 
# save final list
if (open(FILE, ">./params")) {
  $cgi->save(FILE);
  close(FILE);
}
[download]

It depends on what you need to do with the values. Basic assignment to a scalar ( $var ) will lose anything that was in there before, so if you had $var = "first" and then did $var = "second" you just lost the "first" info. In your example, there's no way to conmpare the two. So if you need to keep the info, use another variable for other info.. If you don't care what was in the variable before, then overwriting it is fine... -Syn0

use strict;
my $test = 123;
my $test = 456;
print $test;
[download]

In the code you describe your second declaration of a reference named $q masks your first declaration. The answer is, yes, you are allowed to do it.

However, the prophet Dylan said "to live outside the Law you must be honest." It says in the Talmud that "he who will not take upon himself the yoke of the Law must take upon himself the yoke of the world."

Well, it's like that in Perl also. You can live outside the Law and intentionally write programs that do not run with strict and warnings turned on. But in that case you lose the protection of the Perl gods. Then you must be honest as Dylan said, meaning that the dubious practices that -w guards against must not confuse you and induce coding errors. And you take upon yourself the yoke of the real world as the Talmudic fathers said, which means that in the real world the Perl Porters may have forgotten to test what happens to those programmers who live outside the Law, and the perl interpreter itself might have an undiscovered bug that kills your program.

It is a big world out there. There are endless opportunities to get into trouble. Why ask for trouble by living outside the Law and writing code that fails when run under the -w flag?

Consider what would have happened if Moses's mother had decided to name her son "Abraham" instead of "Moses." Then there would have been two Abrahams in the Bible, just as you have two CGI objects named 'q'. People might have become confused. "Follow Abraham out of Egypt? Abraham's dead!" The Jews might never have entered the Promised Land.

Please stop. Ask not whether thou shalt declare two references with the same variable name, for such a question is not conducive to Perl enlightenment.