Okay, this clears a bit of the mist in my head. Blessing into whatever class I want is certainly, err, what I want. Your example of having an init() method is something I'll have to incorporate into my code; you're right on it being easily understandable. I also notice that you went with Utils and Utils::LowLevel rather than my Utils and LowLevelUtils - obviously I'm still learning the basics of designing a useful package hierarchy.

Now I have a question of laziness. Having re-arranged your code a bit:


#!/usr/bin/perl

{ package Utils;

sub new {
     my $class = shift;
     my $self = {};
     # Bless into the appropriate class
     my $obj = bless $self, $class;
     $obj->init(@_);
     return $obj;
}

sub init {
     # does nothing
}

1; }




{ package Utils::MidLevel;

@Utils::MidLevel::ISA = qw(Utils);

sub init {
     my $self = shift;
     my @args = @_;
     $self->SUPER::init(@args);
     # Now do initialization of object
}

1; }




{ package Utils::LowLevel;

@Utils::LowLevel::ISA = qw(Utils::MidLevel);

sub init {
     my $self = shift;
     my @args = @_;
     $self->SUPER::init(@args);
     # Now do initialization of this class
}

sub foo {
  print "foo\n"
}

1; }

print "Creating new Utils object\n";
my $util = new Utils;
#$util->foo();   # can't find method :(
print "\n";

print "Creating new Utils::MidLevel object\n";
my $mid = new Utils::MidLevel;
#$mid->foo();   # can't find method :(
print "\n";

print "Creating new Utils::LowLevel object\n";
my $low = new Utils::LowLevel;
$low->foo();
print "\n";

exit;

[download]
If I add 
sub foo { Utils::LowLevel::foo }

[download]
into Utils and Utils::MidLevel, then the $util and $mid objects can both find the foo method.

Now, if I'm pig-headed and am dead set against adding those kinds of stubs into Utils and Utils::MidLevel and similarly want to have Utils and Utils::MidLevel be able to access lower-level methods in this manner: 

sub do_highlevel_stuff {
  my $self = shift;
  my $value = $self->get_lowlevel_value;
  # ...
}

[download]
rather than

sub do_highlevel_stuff {
  my $self = shift;
  my $value = Utils::LowLevel::get_lowlevel_value($self);
  # ...
}

[download]

Well - can I have my cake and eat it too? That is, can I keep Utils aware of methods in Utils::MidLevel aware of methods in Utils::LowLevel without having to go through double-colon acrobatics (plus calling methods as regular functions)?

I'm guessing the answer to the above question is no; without stubs and without calling the methods functionally, there is no way to do what I want - just thought I'd ask on the off chance that there's a crafty way to do this. :)

Sorry if this post is hard to read due to incorrect usage of OO terminology (or other CompSci terminology for that matter)

(Good catch on extending Utils with Utils::MidLevel, btw. I have been thinking, "Gee, this really isn't really a low-level table action, nor a high-level action... it's more mid-level...")

blyman
setenv EXINIT 'set noai ts=2'

In reply to Re: Re: Faking new() method in high-level package by belden
in thread Faking new() method in high-level package by belden

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