There's nothing strictly speaking which directly ties the package namespace the contents of a module defines with the filename containing it. You could have a file Fred/Ethyl/Mertzomatic.pm which contained a line package Ricky::Lucy::Recardotron; and use Fred::Ethyl::Mertzomatic; would succeed fine so long as it parsed and returned a true value. You can also have code in several different namespaces in the same file if you like (often used to declare subclasses or subsidiary packages which are pulled in by using the top level module).

However use will look and see if the package corresponding to the name it was given has an import method and will call that method if it exists; since your example doesn't define a method dir::mod->import (directly or through inheritance; you do declare, implicitly through inheritance, mod->import though) Exporter's import is never called and so the assignment of \&mod::hello into *main::hello never occurs and you get the undefined sub error at runtime.

That clear things up?

The cake is a lie.
The cake is a lie.
The cake is a lie.

In reply to Re^3: Unabled to use exported routine by Fletch
in thread Unable to use exported routine by blakesto

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.