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<HTML><HEAD><TITLE>TclJava Library Procedures - Command manual page</TITLE></HEAD><BODY>
<H3><A NAME="M2">INTERFACE</A></H3>
tcl.lang.Command -- The interface for defining new Tcl commands.
<H3><A NAME="M3">METHODS</A></H3>
<P>abstract void <B>cmdProc</B>(Interp <I>interp</I>, TclObject <I>argv[]</I>)
<H3><A NAME="M4">ARGUMENTS</A></H3>
<DL>
<P><DT>Interp <B>interp</B> ()<DD>
The interpreter in which the command is executed.
<P><DT>TclObject <B>argv[]</B> ()<DD>
The array of argument objects passed to the command.
<P></DL>
<H3><A NAME="M5">DESCRIPTION</A></H3>
To write a new Tcl command in Java, you write a class that implement
the <B>Command</B> interface and its <B>cmdProc</B> method. Then,
register the command using the <I>interp</I>.<B><A HREF="../TclJavaLib/createCmd.htm">createCommand</A></B> method.
<P>
<B>cmdProc</B> is invoked to process a Tcl command for
<I>interp</I>. The <I>argv</I> array contains the arguments passed to
the command: <I>argv</I>[0] is the name of the command and the rest of
the array contains the rest of the arguments.
<P>
If the command execution completes normally, this method should pass
the result object back to the interpreter by calling
<I>interp</I>.<B><A HREF="../TclJavaLib/setResult.htm">setResult</A></B> and then return normally. If an error
occurs during the command execution, <B>cmdProc</B> should throw a
<B><A HREF="../TclJavaLib/TclException.htm">TclException</A></B> with appropriate completion code and error messages
(see the manual entry of <B><A HREF="../TclJavaLib/TclException.htm">TclException</A></B> for details.)
<P>
If your command requires clean-up when it's removed from the
interpreter, use the <B><A HREF="../TclJavaLib/CommandWithDispose.htm">CommandWithDispose</A></B> interface instead of the
<B>Command</B> interface. See the <B><A HREF="../TclJavaLib/CommandWithDispose.htm">CommandWithDispose</A></B> manual entry
for details.


<H3><A NAME="M6">EXAMPLE</A></H3>
Here is an example of a Tcl command that adds two integers and returns
the result.
<PRE>import tcl.lang;

class AddCmd implements Command {
    public cmdProc(Interp interp, TclObject argv[])
            throws TclException {
        if (argv.length != 3) {
            throw new TclNumArgsException(interp, 1, argv,
                &quot;num1 num2&quot;);
        }

        int num1 = TclInteger.get(interp, argv[1]);
        int num2 = TclInteger.get(interp, argv[2]);

        TclObject result =
            TclInteger.newInstance(num1 + num2);
        interp.setResult(result);
    }
}</PRE>
<H3><A NAME="M7">EQUIVALENT C FUNCTIONS</A></H3>
<A href="../cFunctions.html">Tcl_CommandProc</A>
<H3><A NAME="M8">SEE ALSO</A></H3>
<B><A HREF="../TclJavaLib/Interp.htm">Interp</A></B>, <B><A HREF="../TclJavaLib/TclException.htm">TclException</A></B>, <B><A HREF="../TclJavaLib/TclInteger.htm">TclInteger</A></B>, <B><A HREF="../TclJavaLib/TclNumArgsException.htm">TclNumArgsException</A></B>, <B><A HREF="../TclJavaLib/TclObject.htm">TclObject</A></B>, <B><A HREF="../TclJavaLib/CommandWithDispose.htm">CommandWithDispose</A></B>
<H3><A NAME="M9">KEYWORDS</A></H3>
<A href="../Keywords/C.htm#command">command</A>, <A href="../Keywords/C.htm#create">create</A>, <A href="../Keywords/I.htm#interpreter">interpreter</A>, <A href="../Keywords/E.htm#exception">exception</A>
<HR><PRE>
<A HREF="../license.html">Copyright</A> &#169; 1998 Sun Microsystems, Inc.
<A HREF="../license.html">Copyright</A> &#169; 1995-1997 Roger E. Critchlow Jr.</PRE>
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