andvari | Event sourcing for node.js

I made a module named Module.pm in lib folder, & then named the package as package lib::Module

You're getting a little confused

When use or require is actioned, Perl will form a relative path from the package name by changing something like My::Other::Module to My/Other/Module.pm using the obvious substitutions

It will look for that relative path in the list of locations in the built-in @INC array, which contains some paths that were defined when perl was built and others that may be added at run time

Up until very recently, @INC contained the current working directory, ., so if you have your module in ./lib/My/Other/Module.pm then the Perl compiler will find it if you use lib::My::Other::Module.pm. But that's not how it's meant to work

You should add ./lib to @INC (using either use lib './lib'^[1] or by adding to the value of the environment variable PERL5LIB) and then use My::Other::Module. That will work fine because perl is looking for the .pm file in in ./lib. The name and path to the .pm file, the package statement, and the use statement should all agree about what the name is

[1] Note that it is a security risk to add relative paths to @INC. That is why . is no longer included as standard in the release client for Perl v5.26. That means you shouldn't use lib './lib' as described above. Instead you need something like use lib '/var/users/Me/Perl/source/lib'

A package name like File::MP3 is just a name. Perl's only requirement is that it has to be unique

But modules are grouped into families in CPAN, and most file-related modules begin with File::. There is also Win32::, Net::, Math:: etc.

It is also used to indicate subsidiary modules in a suite. For instance, Mojo::Message contains the code common to both Mojo::Message::Request and Mojo::Message::Response. But that is a mnemonic for the programmer's convenience only

In the case of Math::Poisson, perl will look for a file Math/Poisson.pm which should have a package declaration package Math::Poisson. If you use that package name elsewhere then anything you declare will be inserted into the module's namespace