quote:

---

Originally posted by Jen Spinney
Hello all.

I have a subroutine that I want to send a bunch of arguments/parameters to.
I find it easier to pass a hash ref to this sub instead of comma separated
arguments because then I don't have to remember the order, and the intention
of each argument is clearer.

Within this sub, I want to check if the hash ref it was passed is complete
(ie it has all the keys it will need).

So far it looks like this (bare bones version):

use strict;
use warnings;

mySub ({
color => 'blue',
phone => '555-5555',
url => 'http://www.google.com',
someKey => 'Some Value'
});

sub mySub
{
my $hash_ref = shift;

if (!exists $hash_ref->{color} ||
!exists $hash_ref->{phone} ||
!exists $hash_ref->{url} ||
!exists $hash_ref->{someKey})
{
die "mySub not provided complete hash ref";
}

#Do stuff
}
__END__

First of all, is there a nicer/easier/prettier way to check for the
existance of all those hash keys?

But my real question is how to make it die with better information. Right
now, if I comment out one of those key/value pairs in the subroutine call,
my script will die with the message
"mySub not provided complete hash ref at line 20". But, the actual
infraction -- the thing I really care about and want to hunt down -- is at
the subroutine call.

Is there a way for mySub to know what line it was called from?

If not, should I go about this using eval blocks and throwing exceptions?

I'm looking for pointers on better perl coding style, so anything you can
throw at me is appreciated (like -- should I not even been sending a hash
ref? Should I use something else?).

Thanks for any help!
- Jen

---

code:
sub mySub
{
   my ($pkg, $file, $line) = caller;

   my $hash_ref = shift;
   my @missing;

   foreach my $key (qw[color phone url someKey])
   {
      push @missing, $key if !exists $hash_ref->{$key};
   }
   if (@missing)
   {
      die "mySub called at line $line is missing required hash key(s):".join ',', @missing;
   }
   #do stuff
}