<H2><A HREF="315BCC5C.A0A78F0@pac.soton.ac.uk">[PREV]</A>  [NEXT]  <A HREF="01I2VWQOLY1U8X43P0@LNS62.LNS.CORNELL.EDU">[PREV Thread]</A>  <A HREF="315BEF11.41C67EA6@micro.ti.com">[NEXT Thread]</A>  <A HREF="news:comp.lang.perl.tk">[Index]</A>  </H2><HR><ADDRESS> lusol@Turkey.CC.Lehigh.EDU (Stephen O. Lidie)
</ADDRESS>
<TITLE> Re: LabEntry</TITLE>
<ADDRESS><H1> Re: LabEntry</H1>
</ADDRESS>
<ADDRESS> 30 Mar 1996 16:06:07 GMT
</ADDRESS>

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<DT> Newsgroups:
<DD> <A HREF="news:comp.lang.perl.tk">comp.lang.perl.tk</A>
<DT> References:
<DD> <A HREF="news:<315BCC5C.A0A78F0@pac.soton.ac.uk"><315BCC5C.A0A78F0@pac.soton.ac.uk></A>
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<PRE>James_Kingdon (jbk@pac.soton.ac.uk) wrote:
: Silly question time...

: When I was trying to implement a composite widget, the documentation
: lead me to LabEntry as an example. When I looked at the source it
: seemed to be a composite widget containing only an entry widget,
: which was a bit mystifying at the time.

: Now I could actually use a labelled entry widget and was wondering
: whether the provided one is really as defective as it seems.

: Am I missing something?

Yes, you're forgetting just how crafty Nick is (;  Essentially, the
Label is created iff you use -label, either when creating the widget
or in a later configure() call:

# Class LabeledEntry

package Tk::LabEntry;
require Tk::Frame;
@ISA = qw(Tk::Frame);

Tk::Widget-&gt;Construct('LabEntry');

sub Populate 
{
 require Tk::Entry;
 # LabeledEntry constructor.
 #
 my($cw, $args) = @_;
 $cw-&gt;SUPER::Populate($args);
      ^^^^^^^^^^^^^^^
 # Advertised subwidgets:  entry.
 my $e = $cw-&gt;Entry();
 $e-&gt;pack('-expand' =&gt; 1, '-fill' =&gt; 'both');
 $cw-&gt;Advertise('entry' =&gt; $e );
 $cw-&gt;ConfigSpecs(DEFAULT =&gt; [$e]);
 $cw-&gt;Delegates(DEFAULT =&gt; $e);
 $cw-&gt;AddScrollbars($e) if (exists $args-&gt;{-scrollbars});
} 

1;

Thus -label ConfigSpecs are created in the Populate found
in Frame.pm, the LabEntry widget's superclass:


sub Populate
{
 my ($cw,$args) = @_;
 $cw-&gt;ConfigSpecs('-labelPack'     =&gt; [ METHOD, undef, undef, undef]);
 $cw-&gt;ConfigSpecs('-labelVariable' =&gt; [ METHOD, undef, undef, undef]);
 $cw-&gt;ConfigSpecs('-label'         =&gt; [ METHOD, undef, undef, undef]);
}

These METHOD specifications say "call the method by the same name as
the -option", and if you examine Frame.pm you'll see where the Label
is auto-created.

Moral of the story:  when creating derived or composite widgets always
call SUPER::Populate().
</PRE>
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