I realised you were looking for callbacks, but given the number of questions here that are of the form "I want to do X, here's my solution for Y - what's wrong?", I like to give MTOWTDI - just incase what you really want is another WTDI.

Now, on to that last code snippet you quoted. I often mix my inheritance with callbacks. For example, the code I posted in Re: String expansion script is in one of my base objects from which many other object types are derived. In general usage, I call it like this: 

  my @strings = $self->expand_string($foo);

[download]
In this module, I'll have my very own expand_variable function which expands the way I want (and usually it defers to $self->SUPER::expand_variable if it can't figure it out). However, in certain cases, I want access to variables that I don't want generic access to - or, perhaps, I can't have generic access to. So I put it my own closure: 
  my @strings = $self->expand_string($foo, sub {
    /^VAR1$/ && return $blah;
    /^VAR2$/ && return @some_list;
    $self->expand_variable()
  } );

[download]
This works pretty much everywhere. $blah, @some_list, and $self are all scoped variables for the closure. And even if the current type doesn't have an expand_variable, that's ok since it is derived off the base with default variable handling.

So, from here, there's another minor point I would make with the code you started with: rather than passing in the variable, is it unreasonable to use $_? You may notice my expand_string code does that with do {local $_ = $var; $self->$func()}. I'm not sure which is faster, localising a global, or passing in a parameter. However, that's not why I'm doing it. I'm doing it because it allows your closure to be smaller because so many of perl's functions assume $_ when not given anything else - exactly why you were using "local $_ = shift" in the first place. I'm just suggesting generalising it so that all closures can gain from the behaviour.

In reply to Re^3: Seeking advice for OO-related strategy by Tanktalus
in thread Seeking advice for OO-related strategy by blazar

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.