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Editorial Team
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Asked: 2026-06-03T13:33:08+00:00

I have a script that I would like to convert to a module and

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I have a script that I would like to convert to a module and call its functions from a Perl script as I do with CPAN modules now. My question is how would others design the module, I’d like to get some idea how to proceed as I have never written a module before. The script, as written now does this:

1) Sets up logging to a db using am in house module
2) Establishes a connection to the db using DBI
3) Fetch a file(s) from a remote server using Net::SFTP:Foreign
4) Process the users in each file and add the data to the DB

The script currently takes command line options to override defaults using Getopt::Long.

Each file is a pipe delimited collection of user data, ~4000 lines, which goes in to the db, provided the user has an entry in our LDAP directory.

So more to the point:
How should I design my module? Should everything my script currently does be moved into the module, or are there some things that are best left in the script. For example, I was thinking of designing my module, so it would be called like this:

use MyModule;

$obj = MyModule->new; // possibly pass some arguments

$obj->setupLogging;

$obj->connectToDB;

$obj->fetchFiles;

$obj->processUsers;

That would keep the script nice and clean, but is this the best idea for the module? I was thinking of having the script retrieve the files and then just pass the paths to the module for processing.
Thanks

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1 Answer

  1. Editorial Team

    I think the most useful question is “What of this code is going to be usable by multiple scripts?” Surely the whole thing won’t. I rarely create a perl module until I find myself writing the same subroutine more than once.

    At that stage I generally dump it into something called “Utility.pm” until that gathers enough code that patterns (not in the gang of four sense really) start to suggest what belongs in a module with well-defined responsibilities.

    The other thing you’ll want to think about is whether your module is going to represent an object class or if it’s going to be a collection of library subroutines.

    In your example I could see Logging and Database connection management (though I’d likely use DBI) belonging in external modules.

    But putting everything in there just leaves you with a five line script that calls “MyModule::DoStuff” and that’s less than useful.

    Most of the time 😉

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