Polymorphism generally refers to the ability to call the correct method on an object depending on its class. It also provides the ability to override methods in derived classes, and still be sure you're getting the one you want.

The term you're looking for is function overloading, which allows for functions of the same name in the same namespace to co-exist, provided they each have different prototypes. This can be achieved as mentioned above, by looking at @_ and if/elsif/else your way through it, or loop, or whatever you want.

What you -can't- do in perl is something like this:

sub blah($) { print "blah\n" }

sub blah($$) { print "blah\n" }
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Prototype mismatch: sub main::blah ($) vs ($$) at test.pl line 3.
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So, in a sense, you can accomplish what you want to in perl, but not the way you can in other languages such as C++. What you're doing in perl doesn't fit the definition of function overloading, since it's actually calling the same function every time, instead of choosing a function to call based on parameters.

Ahh, but see Damian Conway's wonderful Class::Multimethods in the CPAN.

-- Randal L. Schwartz, Perl hacker

Wow! Inheritance-friendly overloading for Perl...

Thanks for the tip, merlyn! :-)

Russ

P.S. CPAN seems to complain about inexact case. Try Multimethods for a temporary shortcut.

sub printheader {
    my $page = shift;

    if($page eq "index") { return printheader_index() }
    elsif($page eq "some other page")
                         { return printheader_some_other_pager() }

    # ...
}
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Polymorphism???

Anyway,
what splinky or someone was talking about is the way to pass parameters to sub's in perl.
Within a subroutine the array @_ contains the parameters passed to that subroutine.

----------------
#!/usr/bin/perl -w
&foo; # the function call to foo with no parameters
&foo(1);
&foo("How's about a piZza?!");
&foo("JAPH");
sub foo
{
  if(@_)
  {
    my $varYouPassed=$_[0];
    print "You passed the var $varYouPassed to foo.";
  }
  else
  {
    print "You passed no vars to foo"
  }
}
---------------
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I think you meant  my $varYouPassed=$_[0]; not my $varYouPassed=$_0;

Remember to use <CODE> arround your code, and not <PRE>.

Paris Sinclair    |    4a75737420416e6f74686572
pariss@efn.org    |    205065726c204861636b6572
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