[tpm] Perl module question

Richard Dice rdice at pobox.com
Fri Sep 7 09:58:16 PDT 2007


The reason why you are experiencing this is because you are confusing
procedural syntax & semantics with object-oriented syntax and semantics.

Here is object-oriented.

use My::Module;
my $object = My::Module->new;
my $result = $object->method(@args);

Internally within My/Module.pm it probably looks something like:

package My::Module;

sub new {
  my $class = shift;
  return bless {}, $class;

sub method {
  my $self = shift;
  my @params = @_;
  ... # do stuff here
  return $value;

Notice the "my $self = shift;" and the "my $class = shift;" lines.  You need
to understand what "->" means.

I could write up a huge email on this subject but really that's a waste of
effort when merlyn has already done it.  Please read:


It is exactly about these concepts.

Also, do you really want to do OO perl?  Maybe procedure Perl modules would
work for your purposes.


On 9/7/07, Madison Kelly <linux at alteeve.com> wrote:
> Hi all,
>    I am quite the module n00b, so please be gentle. :)
>    I've got a few small, simple modules I've written that handle some
> simple functions I use often. What I want to be able to do though is:
> my $foo=My::Module->new();
>    Then be able to call the function/subroutines in there like this:
> my $value=$foo->function($var1, $var2);
>    I had tried to do:
> my $value=My::Module->function($var1, $var2);
>    But the first value picked up in the function is the module name... I
> don't think I should have to say in the module
> sub function
> {
>         my ($null, $var1, $var2)=@_;
>         ...
> }
>    In order to do this. I don't like just calling the function name (as
> I currently do) because some of the funtion names are ambiguous. For
> example, one module is used to validate form values. So the function
> 'phone', 'int_num', 'real_num' and so on are provided by 'NV::Validate'.
> If I want to validate the phone number then, I'd call:
> my ($valid)=phone($form_phone_num);
>    This is fairly ambiguous, and I'd much rather say either:
> my $validate=NV::Validate->new();
> my ($value)=$validate->phone($form_phone_num);
>    Or
> my ($value)=NV::Validate->phone($form_phone_num);
>    But not have the first variable passed being the module name.
> Any tips, pointers or such? Would it help to show some code samples from
> my module?
>    Thanks!
> Madison
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