I found the docs on GET_PROPERTY/SET_PROPERTY a little hard going at
first. I wonder if it could be expanded a bit, perhaps like the
following (formatted for readability, diff below).
GET_PROPERTY $self, $pspec [not a method]
SET_PROPERTY $self, $pspec, $newval [not a method]
"GET_PROPERTY" and "SET_PROPERTY" are called whenever somebody does
"$object->get ($propname)" or "$object->set ($propname => $newval)"
(from other languages, too). The default implementations hold
property values in the object hash, equivalent to
sub GET_PROPERTY {
my ($self, $pspec) = @_;
my $pname = $pspec->get_name;
return (exists $self->{$pname} ? $self->{$pname}
: $pspec->get_default_value); # until set
}
sub SET_PROPERTY {
my ($self, $pspec, $newval) = @_;
$self->{$pspec->get_name} = $newval;
}
Because "$pspec->get_name" converts hyphens to underscores, a prop-
erty "line-style" is in the hash as "line_style".
These methods let you store/fetch properties in any way you need
to. They don't have to be in the hash, you can calculate some-
thing, read a file, whatever.
Most often you'll write your own "SET_PROPERTY" so you can take
action when a property changes, like redraw or resize a widget.
Eg.
sub SET_PROPERTY {
my ($self, $pspec, $newval) = @_;
my $pname = $pspec->get_name
$self->{$pname} = $newval; # ready for default GET_PROPERTY
if ($pname eq 'line_style') {
$self->queue_draw; # redraw with new lines
}
}
"GET_PROPERTY" is different from a C get_property method in that
the perl method returns the retrieved value. For symmetry, the
$newval and $pspec args on "SET_PROPERTY" are swapped from the C
usage.
--- Subclass.pm 02 Jul 2005 10:35:15 +1000 1.13
+++ Subclass.pm 21 Apr 2008 11:12:33 +1000
@@ -141,31 +141,47 @@
=item GET_PROPERTY $self, $pspec [not a method]
-Get a property value, see C<SET_PROPERTY>.
-
-The default implementation looks like this:
-
- my ($self, $pspec) = @_;
- return ($self->{$pspec->get_name} || $pspec->get_default_value);
-
=item SET_PROPERTY $self, $pspec, $newval [not a method]
C<GET_PROPERTY> and C<SET_PROPERTY> are called whenever somebody does
C<< $object->get ($propname) >> or C<< $object->set ($propname => $newval) >>
-(from other languages, too). This is your hook that allows you to
-store/fetch properties in any way you need to (maybe you have to calculate
-something or read a file).
+(from other languages, too). The default implementations hold property
+values in the object hash, equivalent to
+
+ sub GET_PROPERTY {
+ my ($self, $pspec) = @_;
+ my $pname = $pspec->get_name;
+ return (exists $self->{$pname} ? $self->{$pname}
+ : $pspec->get_default_value); # until set
+ }
+ sub SET_PROPERTY {
+ my ($self, $pspec, $newval) = @_;
+ $self->{$pspec->get_name} = $newval;
+ }
+
+Because C<< $pspec->get_name >> converts hyphens to underscores, a property
+C<"line-style"> is in the hash as C<line_style>.
+
+These methods let you store/fetch properties in any way you need to. They
+don't have to be in the hash, you can calculate something, read a file,
+whatever.
+
+Most often you'll write your own C<SET_PROPERTY> so you can take action when
+a property changes, like redraw or resize a widget. Eg.
+
+ sub SET_PROPERTY {
+ my ($self, $pspec, $newval) = @_;
+ my $pname = $pspec->get_name
+ $self->{$pname} = $newval; # ready for default GET_PROPERTY
+
+ if ($pname eq 'line_style') {
+ $self->queue_draw; # redraw with new lines
+ }
+ }
C<GET_PROPERTY> is different from a C get_property method in that the
perl method returns the retrieved value. For symmetry, the C<$newval>
-and C<$pspec> args on C<SET_PROPERTY> are swapped from the C usage. The
-default get and set methods store property data in the object as hash
-values named for the parameter name.
-
-The default C<SET_PROPERTY> looks like this:
-
- my ($self, $pspec, $newval) = @_;
- $self->{$pspec->get_name} = $newval;
+and C<$pspec> args on C<SET_PROPERTY> are swapped from the C usage.
=item FINALIZE_INSTANCE $self [not a method]
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