tools/perl-5.8.0/man/man3/Tk::Derived.3

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.\" ========================================================================
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.IX Title "DERIVED 1"
.TH DERIVED 1 "2000-12-30" "perl v5.8.0" "User Contributed Perl Documentation"
.SH "NAME"
Tk::Derived \- Base class for widgets derived from others
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 3
\&  package Tk::Whatever;
\&  require Tk::Something;
\&  require Tk::Derived;
.Ve
.PP
.Vb 1
\&  @ISA = qw(Tk::Derived Tk::Something);
.Ve
.PP
.Vb 8
\&  sub Populate
\&  {
\&   my ($cw,$args) = @_;
\&   ...
\&   $cw->SUPER::Populate($args);
\&   $cw->ConfigSpecs(...);
\&   ...
\&  }
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
Tk::Derived is used with perl5's multiple inheritance to override some
methods normally inherited from Tk::Widget.
.PP
Tk::Derived should precede any Tk widgets in the class's \f(CW@ISA\fR.
.PP
Tk::Derived's main purpose is to apply wrappers to \f(CW\*(C`configure\*(C'\fR and \f(CW\*(C`cget\*(C'\fR
methods of widgets to allow the derived widget to add to or modify behaviour
of the configure options supported by the base widget.
.PP
The derived class should normally override the \f(CW\*(C`Populate\*(C'\fR method provided
by Tk::Derived and call \f(CW\*(C`ConfigSpecs\*(C'\fR to declare configure options.
.PP
The public methods provided by Tk::Derived are as follows:
.IP "\->ConfigSpecs(\-\fIkey\fR => [\fIkind\fR, \fIname\fR, \fIClass\fR, \fIdefault\fR], ...)" 4
.IX Item "->ConfigSpecs(-key => [kind, name, Class, default], ...)"
.SH "SEE ALSO"
.IX Header "SEE ALSO"
Tk::ConfigSpecs
Tk::mega