stk/Help/listener.n.html

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<HTML><HEAD><TITLE>Tk Built-In Commands - listener manual page</TITLE></HEAD>
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<H2><IMG ALIGN=BOTTOM SRC="./Img/ManPageGreen.gif"> listener</H2>
<I>Create and manipulate listener widgets</I><P><IMG ALIGN=TOP SRC="./Img/line-red.gif">
<H3><A NAME="M2">SYNOPSIS</A></H3>
(<B>listener</B><I> widget-name </I>?<I>options</I>?)<BR>
<BR>
<H3><A NAME="M3">WIDGET-SPECIFIC OPTIONS</A></H3>
<DL>
<P>
<DT><I>Name</I>: <B></B>
<DT><I>Class</I>: <B></B>
<DT><I>Option keyword</I>: <B><A NAME="M4">:command</A></B>
<DT><I>STklos slot name</I>: <B>command</B>
<DD>Specifies a STk procedure to associate with the listener. This procedure
is invoked when a complete s-expr is entered in the listener. This s-expr is
passed as a string to the procedure. The procedure must return the string
which will be inserted in response to the s-expr input. The default procedure
is the Identity procdure.
<P>
<P>
<DT><I>Name</I>: <B></B>
<DT><I>Class</I>: <B></B>
<DT><I>Option keyword</I>: <B><A NAME="M5">:output-color</A></B>
<DT><I>STklos slot name</I>: <B>output-color</B>
<DD>Specifies the color used the output lines
<P>
<P>
<DT><I>Name</I>: <B></B>
<DT><I>Class</I>: <B></B>
<DT><I>Option keyword</I>: <B><A NAME="M6">:prompt-color</A></B>
<DT><I>STklos slot name</I>: <B>prompt-color</B>
<DD>Specifies the color used for the prompt
<P>
<P>
<DT><I>Name</I>: <B></B>
<DT><I>Class</I>: <B></B>
<DT><I>Option keyword</I>: <B><A NAME="M7">:prompt</A></B>
<DT><I>STklos slot name</I>: <B>prompt</B>
<DD>Specifies the prompt used for reading s-expr. Defaults to &quot;&gt; &quot;
<P>
</DL>
<H3><A NAME="M8">DESCRIPTION</A></H3>
The <B>listener</B> procedure creates a new text window (given by the
<I>widget-name</I> argument) and associates it bindiangs suitable for a listener.
Since a listener is in fact a text widget, all the options of <B><A HREF="./text.n.html">text</A></B>
are applicable to a listener.
The <B>listener</B> procedure returns its
<I>widget-name</I> argument. At the time this procedure is invoked,
there must not exist a window named <I>widget-name</I>, but
<I>widget-name</I>'s parent must exist.
<P>
A listener is a widget for doing interactive I/O. Typical usage for
this widget consists of a text window whose inputs are sent to the
Scheme evaluator and whose result is displayed in the listener. An
example for this is shown at the end of this page.
<H3><A NAME="M9">WIDGET PROCEDURE</A></H3>
All the <B><A HREF="./text.n.html">text</A></B> procedure are avialble for a listener, plus
<P>
<DL>
<DT><A NAME="M10">(<B>listener-insert-string</B> <I>widget-name str</I>)</A><DD>
inserts the string <I>str</I> just before the input prompt.
<P>
</DL>
<H3><A NAME="M11">EXAMPLE</A></H3>
Hereafter is a simple use of the listener widget which interact with the
evaluator.
<P>
<PRE>(listener '.t :width 50
:height 10
:command (lambda (x)
(eval-string x (global-environment))))
(pack .t)</PRE>
<H3><A NAME="M12">DEFAULT BINDINGS</A></H3>
The defaults bindings are identical to the <B><A HREF="./text.n.html">text</A></B> bindings.
<H3><A NAME="M13">SEE ALSO</A></H3>
<B><A HREF="./text.n.html">text</A></B>
<P><IMG ALIGN=TOP SRC="./Img/line-red.gif">
<A HREF=./STk-hlp.html><IMG ALIGN=BOTTOM SRC="./Img/RefBookGreen.gif"> Back to the <B>STk</B> main page</A>
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