Here is some simple code for you to play with:

A Perl prototype is only marginally useful.
There is no "type checking".

One thing that a prototype can do is to allow you to call a user sub without () around the args...sort of mimicking a Perl built in function. I personally think this is a bad idea and use of prototype. I always enclose args in () for my functions.

Play with the below code which just shows a simple scenario with $ representing a scalar value. 

#!/usr/bin/perl -w
use strict;

some_sub(1,2);    #called too early warning error
                  #but note that the code still runs!

sub some_sub($$) #this sub requires 2 scalars
{
   my ($a,$b) = @_;
   print "$a,$b\n";
}

some_sub 6,8;      #ok,now this is just fine
some_sub 10,11,12; #too many argument error

__END__
main::some_sub() called too early to check prototype at C:\TEMP\perl33
+.pl line 6.
1,2

if you reverse order or add proto above call:
sub some_sub($$);
some_sub(1,2);

sub some_sub($$)
{
   my ($a,$b) = @_;
   print "$a,$b\n";
}
Perl will be happy, but to what effect?

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In reply to Re: subroutine prototype in Perl by Marshall
in thread subroutine prototype in Perl by pavunkumar

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