Beefy Boxes and Bandwidth Generously Provided by pair Networks
good chemistry is complicated,
and a little bit messy -LW

comment on

( #3333=superdoc: print w/replies, xml ) Need Help??
Interesting code you have there - i can't tell if it's a hack on the decorator pattern or maybe even the state pattern. At any rate, i think i see what the goal is:

You instantiate the First class and test to see if it does the job, if it doesn't, revert to the Second class. This is cool, but it's a maintenance nightmare should you decide to add a Third, or a Fourth, ... all the way to the Nth possible class.

I rewrote your code and added some tests - here is the solution domain:

0-5: fail 6-9: second handles 10-: first handles
And the code:
use strict; use Data::Dumper; package First; sub new { my $class = shift; my $self = { foo => 'bar' }; return bless $self, $class; } sub test { my $self = shift; my $arg = shift || 10; return ($arg > 9) ? "okay" : bless $self, 'Second'; } package Second; sub new { my $class = shift; my $self = { foo => 'qux' }; return bless $self, $class; } sub test { my $self = shift; my $arg = shift || 4; return ($arg > 5) ? "okay" : undef; } package main; my $arg = shift || 10; my $t = First->new(); if (ref $t->test($arg)) { warn "first failed, trying second..."; die "second failed" unless $t->test($arg); } print (ref $t, " passed\n"); print Dumper $t;
Try it out. Notice the very last expression which outputs the Dump of the object - notice how even though it might belong to package First or Second - $self is the same. That may or may not be a problem for you, because the technique to change $t from First to Second only changes it's package, not it's attributes.

In conclusion, the only two problems i see are

  1. extensibility - need to generalize First, Second, Third, etc.
  2. not inheriting attributes from oringal class - but this might your 'feature' ...
Three cheers for flexiblity!


(the triplet paradiddle)

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

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

  • Are you posting in the right place? Check out Where do I post X? to know for sure.
  • Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
    <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>
  • Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
  • Want more info? How to link or or How to display code and escape characters are good places to start.
Log In?

What's my password?
Create A New User
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others scrutinizing the Monastery: (4)
As of 2021-05-14 18:51 GMT
Find Nodes?
    Voting Booth?
    Perl 7 will be out ...

    Results (150 votes). Check out past polls.