Beefy Boxes and Bandwidth Generously Provided by pair Networks RobOMonk
Your skill will accomplish
what the force of many cannot
 
PerlMonks  

resolved: Shorter than ternary?

by Spidy (Chaplain)
on Nov 15, 2007 at 21:04 UTC ( #651075=perlquestion: print w/ replies, xml ) Need Help??
Spidy has asked for the wisdom of the Perl Monks concerning the following question:

Greetings, fellow monks.

I have a module I'm working on that accepts a hash of arguments to one of its functions. If no hash is supplied, it fills in the arguments itself. This is the code I am using:

    my $defaults = {
        requires_login         => $_{'requires_login'} ? $_{'requires_
+login'} : 0,
        template_file         => $_{'template_file'} ? $_{'template_fi
+le'} : 'template.tmpl',
        inner_template => '',
    };

[download]

However, there are a lot of defaults I need to do this for. Is there any way to write this in a shorter form and have it work?

Thanks,

Spidy



Edit: I ended up just hacking a piece of HTML::Template to suit my needs:

sub loadOptions {
    my $argsref = shift;
    my $options = shift;
    for(my $i = 0; $i < @{$argsref};$i+=2) {
        $options->{lc(${$argsref}[$i])} = ${$argsref}[($i+1)];
    }
    return $options;
}

[download]

And then it's called using:

$defaults = loadOptions([@_],$defaults);

[download]
website army

Comment on resolved: Shorter than ternary?
Select or Download Code
Re: Shorter than ternary?
by FunkyMonk (Abbot) on Nov 15, 2007 at 21:12 UTC
    What about... 
    my $defaults;
$defaults->{$_} = $_{$_} ? $_{$_} : 0
    for qw/ requires_login template_file /;
$defaults->{inner_template} = '',

    [download]

[reply]
[d/l]
[select]
Re: Shorter than ternary?
by jhourcle (Prior) on Nov 15, 2007 at 21:12 UTC

    Please define 'shorter'. If you just want less typing, use a subroutine:

    #nvl : a common pl/sql command
sub nvl { defined ($_[0]) ? $_[0] : $_[1] }

    [download]

    Or, you can use the fact that perl will use the second occurance of items in the assignment, but it might be less obvious, and they can override anything:

    my $defaults = {
    requires_login => 0,
    template_file => 'template.tmp',
    inner_template => '',
    %_
}

    [download]
[reply]
[d/l]
[select]
Re: Shorter than ternary?
by kyle (Abbot) on Nov 15, 2007 at 21:12 UTC

    Something like this? 

    use Data::Dumper;

sub_with_defaults( { foo => 'real_foo' } );

sub sub_with_defaults {
    my %DEFAULTS = ( foo => 'default_foo',
                     bar => 'default_bar',
                     );
    my %params = ( %DEFAULTS, %{shift @_} );

    print Dumper( \%params );
}
__END__
$VAR1 = { 
          'bar' => 'default_bar',
          'foo' => 'real_foo'
        };

    [download]
[reply]
[d/l]
Re: resolved: Shorter than ternary?
by gamache (Friar) on Nov 15, 2007 at 21:58 UTC
    To allow defaults and/or enforce mandatory values in a hashref: 
    my %args = (
    key1    =>  'specified 1',
    key3    =>  'THIS SPACE FOR RENT'
);

my $hr = {
    key1    =>  'default 1',
    key2    =>  'default 2',

    %args,

    key3    =>  'enforced 3'
};

## now:
##  $hr->{key1} == 'specified 1'
##  $hr->{key2} == 'default 2'
##  $hr->{key3} == 'enforced 3'

    [download]
    In English: when building a hash, key => value pairs override the previous value for the given key. And tossing a %hash (or @array, if it looks like a hash) in the mix will just expand itself to a list of key, value, key, value...
[reply]
[d/l]
[select]

Back to Seekers of Perl Wisdom

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: perlquestion [id://651075]
Approved by philcrow
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others meditating upon the Monastery: (7)
As of 2013-05-23 01:48 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    The best material for plates (tableware) is:









    Results (473 votes), past polls