Re^2: Program structure: subs vs modules vs Selfloader

Arunbear, thanks for the example. However, if I'm permitted, I have a follow-up question: does coding it the way you do, by "requiring" the module only if the condition is met, only load the module when it runs?

Normally I reference the module like this:

use SomeModule.pm
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at the start of my program, right after the shebang. Thanks.

Update: Well, I Googled and found this informative piece on modules, libraries, etc. I see now that Perl doesn't deal with a require until it comes across it in the code.

—Brad
"Don't ever take a fence down until you know the reason it was put up. " G. K. Chesterton

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Re^3: Program structure: subs vs modules vs Selfloader by vek (Prior) on Jun 20, 2004 at 18:31 UTC
If you `use` a module, Perl deals with it at compile time. If you `require` a module, Perl deals with it at run time. I typically like to `use` a module because it allows me to check everything via a `perl -c someprog.pl` after I've finished coding. It I used `require` instead, I wouldn't find out that something was wrong until I ran the program for the first time. YMMV, just my own personal preference. `require` is handy though if your program needs to do something based on whether you have a module installed on your system. You can test for this at runtime. `#!/usr/bin/perl -w use strict; # do we have FOO::Bar on this system? eval { require FOO::Bar }; if ($@) { # FOO::Bar not installed } else { # FOO::Bar installed }` [download] -- vek --	[reply] [d/l] [select]

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Re^3: Program structure: subs vs modules vs Selfloader
by vek (Prior) on Jun 20, 2004 at 18:31 UTC

If you use a module, Perl deals with it at compile time. If you require a module, Perl deals with it at run time.

I typically like to use a module because it allows me to check everything via a perl -c someprog.pl after I've finished coding. It I used require instead, I wouldn't find out that something was wrong until I ran the program for the first time. YMMV, just my own personal preference.

require is handy though if your program needs to do something based on whether you have a module installed on your system. You can test for this at runtime.

#!/usr/bin/perl -w

use strict;

# do we have FOO::Bar on this system?
eval { require FOO::Bar };
if ($@) {
   # FOO::Bar not installed
} else {
   # FOO::Bar installed
}
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-- vek --

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