I usually do something like this:

sub do_something {
  my $args = shift;
  my $result = 0;  # or "", or undef, or whatever
  my @errors = ();

  # Validate staff
  push @errors, "Where's the email?" unless ($args->{email});
  push @errors, "Bad email" unless ($args->{email} =~ /\@/);
  # ...

  unless (@errors) {
    # Do something here
    # ...
  }

  return $result, @errors;  
}
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This approach provides a convinient way to display errors later on, if need be, while still validating provided data and saving on processing if ugly staff was given.

sub display_status {
  my @errors = @_;
  if (@errors) {
    print "Operation failed due to following errors:\n";
    foreach my $error (@errors) {
      print "\t- $error\n";
    }
  }
  else {
    print "Operation succeded\n";
  }
}
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Now, if you need to display only errors you can do:

my ($result,@errors) = do_something(\%args);
if (@errors) {
  display_status(@errors);
}
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If you need to show to the user an OK message too, then just call display_status(@errors) unconditionally.

my two cents

Leonid Mamtchenkov aka TVSET