Re: -w in production environment

You actually want this:

if (exists $USER{coffee} && $USER{coffee} > 5){$msg='You drink too muc
+h coffee'}
[download]

It checks that the coffee key exists in %USER. You can just use

if ($USER{coffee} && $USER{coffee} > 5){$msg='You drink too much coffe
+e'}
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It will get rid of the warning, but won't actually do anything useful. exists checks that the coffee key was created. This check actually tells you a potentially relevant piece of information. e.g

if (! exists $USER{coffee}){
    $msg = 'You drank no coffee?!?!';
}
elsif ($USER{coffee} > 5){
    $msg='You drink too much coffee';
}
else {
    $msg='You drank a moderate amount of coffee';
}
[download]

There is no point in adding code just to get rid of a warning if the new code does nothing useful! It is a poor practice to get into and can be confusing to the people that have to maintain you application. Like Abigail said check your input to make sure no one made a mistake inputting a value (or is pulling a fast one on you).

This doesn't seem to be the behaviour that you want.

HTH,
Clayton

Update:
I removed a section that said testing if a non exsistant key was defined would autovivify it and added my support for Abigail's answer. I swear with God as my witness...

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Re: Re: -w in production environment by arturo (Vicar) on Jul 06, 2001 at 01:45 UTC
If you used defined $USER{coffee} as a check it will actually autovivify (automatically create) the coffee key as it does when you do your current test. That's not true: `use warnings; use strict; my %c = ( hey=>'Joe', where=>'you goin\'', with=>'that gun in your hand'); if (defined $c{Hendrix}) { print "Jimi is alive and well\n"; } foreach ( sort keys %c ) { print "Key : $_ => $c{$_}\n"; }` [download] This does not print "Hendrix" and yield up a warning on the loop that goes through the keys (Perl 5.6.1, Win32). Of course `defined $hash{key}` and `exists $hash{key}` do test for different things: `$hash{key} = undef; #defined $hash{key} false, exists $hash{key} true` [download] `perl -e 'print "How sweet does a rose smell? "; chomp ($n = <STDIN>); +$rose = "smells sweet to degree $n"; other_name = rose; print "$oth +er_name\n"'` [download]	[reply] [d/l] [select]

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Re: Re: -w in production environment
by arturo (Vicar) on Jul 06, 2001 at 01:45 UTC

If you used defined $USER{coffee} as a check it will actually autovivify (automatically create) the coffee key as it does when you do your current test.

That's not true:

use warnings;
use strict;

my %c = ( hey=>'Joe',
      where=>'you goin\'',
      with=>'that gun in your hand');

if (defined $c{Hendrix}) {
    print "Jimi is alive and well\n";
}

foreach ( sort keys %c ) {
    print "Key : $_ => $c{$_}\n";
}
[download]

This does not print "Hendrix" and yield up a warning on the loop that goes through the keys (Perl 5.6.1, Win32).

Of course defined $hash{key} and exists $hash{key} do test for different things:

$hash{key} = undef; #defined $hash{key} false, exists $hash{key} true
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perl -e 'print "How sweet does a rose smell? "; chomp ($n = <STDIN>); 
+$rose = "smells sweet to degree $n"; *other_name = *rose; print "$oth
+er_name\n"'
[download]

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