Beefy Boxes and Bandwidth Generously Provided by pair Networks
Clear questions and runnable code
get the best and fastest answer
 
PerlMonks  

Re: $foo->bar = 14;

by hypochrismutreefuzz (Scribe)
on Jan 04, 2003 at 10:20 UTC ( #224241=note: print w/ replies, xml ) Need Help??


in reply to $foo->bar = 14;

Another way to encapsulate a property is with a psuedo hash. The fields pragma gives the $self variable the instance variables and the new() returns a blessed reference. Then, another psuedo hash is made, $prop, that acts as a static variable that maps the property names to code references. Then the method 'property' is called thus: $obj->property('propertyname', 'value' ...);

The example I give uses a colorref type of variable that takes a red, blue, and green integer values and returns a hex value that you could put in an HTML attribute, say.
package ClassExample; use strict; use warnings; use fields qw/color texture/; my $prop = fields::phash( [qw/color texture/], [\&color_prop, \&texture_prop] ); sub create { my $class = shift; my $self = fields::new($class) unless ref($class); return $self; } sub property { my $self = shift; my ($propname, @params) = @_; $self->{$propname} = &{ $prop->{$propname} }(@params) if @params; return $self->{$propname}; } # these subroutines could be isolated in another module and imported # PRIVATE!!! keep out! sub color_prop { my %colors = @_; my $ok = 0; for (qw/red green blue/) { if (exists $colors{$_}) { next if $colors{$_} < 0; next if $colors{$_} > 0xff; $ok++; } } die "@_ is not a red/green/blue color ref" unless $ok == 3; return sprintf('%02X%02X%02X', $colors{red}, $colors{green}, $colo +rs{blue}); } sub texture_prop { my $texture = shift; my $ok = 0; for (qw/rough smooth crinkly/) { if ($texture eq $_) { $ok = 1; last; } } die "$texture is not rough/smooth/crinkly texture value" unless $o +k; return $texture; } 1; # text_example.pl #!/usr/local/bin/perl use strict; use warnings; use ClassExample; my $clex = ClassExample->create(); $clex->property('color', 'green', 0xde, 'red', 255, 'blue', 1); $clex->property('texture', 'rough'); my $printthing = <<"end_of_print"; Properties of %s: Texture: %s Color: %s end_of_print print "\n"; printf ($printthing, '$clex', $clex->property('texture'), $clex->prope +rty('color')); my $texture = $clex->property('texture', 'smooth'); my $colorref = $clex->property('color', red=>0x52, green=>0x20, blue=>0x11); printf ($printthing, '$clex', $texture, $colorref);

By running test_example.pl you get the output

e:\Borland\Programs>test_example.pl

Properties of $clex:
Texture: rough
Color:   FFDE01

Properties of $clex:
Texture: smooth
Color:   522011

I tested it using ActiveState Perl 5.8 under Windows 2000.


Comment on Re: $foo->bar = 14;
Download Code

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://224241]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others exploiting the Monastery: (8)
As of 2015-07-04 15:00 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    The top three priorities of my open tasks are (in descending order of likelihood to be worked on) ...









    Results (60 votes), past polls