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Re: using 'my'

by Anonymous Monk
on Jun 21, 2001 at 20:16 UTC ( #90435=note: print w/ replies, xml ) Need Help??


in reply to using 'my'

You don't have to 'use strict' but it certainly helps you catch those hard to see errors.

I often use strict and declare my variables global.

#!/usr/bin/perl -w

use strict;
my($dummy1,$dummy2,$dummy3);

...
Kind of lazy, but I can use the variables everywhere in the script and I still catch the errors. Heffa K


Comment on Re: using 'my'
Re: Re: using 'my'
by Hero Zzyzzx (Curate) on Jun 21, 2001 at 20:35 UTC

    I'm sorry, but those aren't global variables, they are just lexically scoped variables at the "highest level" of a script.

    Declaring variables like this is bad practice, in my mind if you're doing CGI programming, or any other perl programming that creates persistent compiled copies of perl scripts.

    This type variable sharing will give the famous "variable will not stay shared" error with mod_perl.

    If you're never going to use mod_perl, then you can keep on coding this way. A better way would be to pass all variables to your subroutines as arguments, thusly:

    first_sub('Testing, testing',' one, two, three'); sub first_sub { my ($var,$var2)=@_; second_sub($var,$var2); } sub second_sub { my ($variable,$variable2)=@_; print $variable.$variable2; }

    This more rigid, but it really helps you keep your variables in line, making for easier maintaince down the road. You can reuse the subroutine elsewhere, 'cuz you know exactly what goes in and what comes out.

    You could declare the variables as globals with the closed perl equivalent, thusly:

    use strict; use vars qw/$var1 $var2/;

    but this is bad programming practice generally, as I understand it. (why is this? Is it due strictly to memory usage?)

    Update: Of course. I must have had a brain cramp. See TGI's post below.

      Hero Zzyzzx said: You could declare the variables as globals...but this is bad programming practice generally, as I understand it. (why is this? Is it due strictly to memory usage?)

      You answered your own question as to why globals are bad, when you said You can reuse the [code] elsewhere, 'cuz you know exactly what goes in and what comes out. It has to do with modularity of code. It's a lot easier to make everything global and share data around indiscriminantly, but maintaining such code can be hellish.

      Perl, more than any other language I've used, gives you the flexibility to 'get stupid.' That's what makes Perl so great, sometimes you just need to get something done, and its easier and faster to do it if you do it 'the wrong way'.


      TGI says moo

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