On Sunday 19 December 2004 20:48, JupiterHost.Net wrote:
> Hello group,
Hi,
> I'm trying to subclass a module (at least I think its what is called
> subclassing...)
I'm not sure, but I think subclassing is the appropriate term for this ;-)
> This example below works but I'd like to package GD::Image::Foo in its
> own module, how would I go about doing that? perldoc perlmod and
> perlmodlib didn't seem to address that issue unless of course I'm
> confused which is most likely the case ;p
>
I think what you want to do is to create an own class that inherits from
GD::Image. In Perl (5), a class is basically a package, so you've been on the
right track when you wrote this sub starting with
sub GD::Image::Foo {
...
Now just create a new file called Foo which you put into the folder GD/Image,
so that it can be found by perl.
This class should probably look similar to this (UNTESTED):
##############################################
#!/usr/bin/perl
# file: GD/Image/Foo.pm
# the package name is the class name
package GD::Image::Foo;
use strict;
use warnings;
use GD;
# this declares that you want to inherit from GD::Image
our @ISA = qw(GD::Image);
sub Foo {
my $self = shift;
# work with the image
}
##############################################
Now you should be able to use it instead of the usual image:
[..]
> I'd like that to be:
>
> #!/usr/bin/perl
>
> use strict;
> use warnings;
> #use GD;
I think you don't need this line any more because of the next one.
> use GD::Image::Foo; # has sub GD::Image::Foo {} in it ...
>
> # my $image = GD::Image->new(42,21);
You've got to instantiate an object of your new class instead - try:
my $image = GD::Image::Foo -> new(42,21);
> my $white = $image->colorAllocate(255,255,255);
> $image->transparent($white);
>
> $image->Foo(1,5,9);
>
> Any docs/ideas most appreciated!
>
> TIA
I'm not very experienced with OOP in perl, but I think this should be it - if
you got the Camel book at hand, take a look into the OOP chapter. It's very
comprehensible (and funny). If you do not have the camel book, give it to
yourself as a christmas present ;-)
HTH,
Philipp
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