If/Else or Unless Not Triggering Correctly

ljamison has asked for the wisdom of the Perl Monks concerning the following question:

Hail Monks!

I have a module with a function which should only trigger if certain conditions are true/false (depending on if I use if or unless) but the way it is currently triggering it appears that the if/unless is being ignored. I'm under the impression it has to do with the priority order of the operators but I'm not certain.

Attempt using unless:

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

########################
## unrelated code here #
########################

sub triggerNotification {
    my $data = @_; # data passed into function to be processed
    
    unless($data == 'ARCHITECH' || $data == 'CURR-LIB'
        || $data == 'MARKET_PL') {
            
            # send email notification

    }
}
[download]

Attempt using if/else:

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

########################
## unrelated code here #
########################

sub triggerNotification {
    my $data = @_; # data passed into function to be processed
    
    if(!($data == 'ARCHITECH') || !($data == 'CURR-LIB')
        || !($data == 'MARKET_PL')) {
            
            # send email notification

    }
    else {
        # do nothing
    }
}
[download]

Both of these attempts failed to prevent the email notification from being sent out and I'm not sure what I have written wrong. Thank you in advance for any advice!

Comment on If/Else or Unless Not Triggering Correctly Select or Download Code

Replies are listed 'Best First'.
Re: If/Else or Unless Not Triggering Correctly by stevieb (Canon) on Apr 21, 2016 at 14:25 UTC
Use `eq` to compare strings. `==` is for digity-type things: `unless( $data eq 'ARCHITECH' \|\| $data eq 'CURR-LIB' \|\| $data eq 'MARKET_PL +'){ ... }` [download]	[reply] [d/l] [select]
Re^2: If/Else or Unless Not Triggering Correctly by misterperl (Friar) on Apr 21, 2016 at 14:54 UTC
`else { # do nothing }` [download] is exactly the same as `# do nothing` [download] (THAT IS if an optimizer zapped this clause for you. Otherwise it's not quite the same because it wastes machine cycles)	[reply] [d/l] [select]
Re: If/Else or Unless Not Triggering Correctly by talexb (Chancellor) on Apr 21, 2016 at 17:21 UTC
As a matter of style, I prefer to use a hash to figure out whether something is in a set, or not. So your code would be simplified to the following: `sub triggerNotification { my ( $data ) = @_; my %message_classes = ( 'ARCHITECH' => 1, 'CURR-LIB' => 1, 'MARKET_PL' => 1, ); if ( not exists $message_classes{ $data } ) { # Send an E-Mail notification if the message type is not listed. } }` [download] Using 'data' has a variable name is amusing -- you can probably find a better name than that. :) Alex / talexb / Toronto Thanks PJ. We owe you so much. Groklaw -- RIP -- 2003 to 2013.	[reply] [d/l]
Re: If/Else or Unless Not Triggering Correctly by Laurent_R (Canon) on Apr 21, 2016 at 19:08 UTC
In addition to the already-mentioned fact that you should use `eq` instead of `==` operator for string comparison (or a hash lookup as suggested by talexb), this code line is also not good: `my $data = @_; # data passed into function to be processed` [download] Assigning a scalar to an array is not likely to give you what you want. Try instead: `my $data = @_[0]; # data passed into function to be processed` [download] or: `my ($data) = @_; # data passed into function to be processed` [download] or: `my $data = shift; # data passed into function to be processed` [download]	[reply] [d/l] [select]
Re: If/Else or Unless Not Triggering Correctly by Cuhulain (Beadle) on Apr 22, 2016 at 15:55 UTC
I think your Boolean logic for the "if" code is wrong. From `https://en.wikipedia.org/wiki/De_Morgan%27s_laws`: "not (A or B)" is the same as "(not A) and (not B)" Using your example, where a condition like $data eq 'ARCHITECH' is represented by letter A: `unless( A or B or C )` means the same as: `if not ( A or B or C )` which, by De Morgan's Law, is equivalent to : `if ( not-A and not-B and not-C )` But you have written the "if" code as: `if ( not-A or not-B or not-C )` which does definitely not match your "unless" code.	[reply] [d/l] [select]