Rather than hardcoding the fallback into the class itself, why not implement a dispatcher object, which, given the current class (available through caller()) and the kind of failure (?) does a lookup to determine the next class to try, to wit:

my %FSM = ( First => { fail_a => 'Second',
                       fail_b => 'Third',
                       pass   => undef },  # we're done
            Second =>{ fail_c => 'Third',
                       pass   => undef ) );

[download]

Rather like a sparse-matrix.

Then the code within any of the classes 'First', "Second' or 'Third' would merely consult the %FSM hash for what to do next. This brings up the problem of how (where?) to scope the %FSM hash. This should probably be a member within a common base-class:

package Base;

sub new {
    my $class = shift;
    my $self = { FSM => {First => { fail_a => 'Second',
                                    fail_b => 'Third',
                                    pass   => undef },  # we're done
                         Second =>{ fail_c => 'Third',
                                    pass   => undef )} };
    bless $self, $class;
    return $self;
}

package First;
use base qw( Base );

sub new {
  # ...
}

package Second;
use base qw( Base );

sub new {
  # ...
}

# ... and so on

[download]

Any of the derived classes could access it as $self->{FSM}.

dmm

You can give a man a fish and feed him for a day ...
Or, you can teach him to fish and feed him for a lifetime

In reply to Re(2): Replacing namespaces by dmmiller2k
in thread Replacing namespaces by smferris

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.