'\"
'\" Copyright (c) 1993-1998  Lucent Technologies, Inc.
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\"
'\" RCS: $Id: is.n,v 1.3 2002/04/25 22:27:31 davygrvy Exp $
'\"
.so man.macros
.TH is n 3.3 itcl "[incr\ Tcl]"
.BS
'\" Note:  do not modify the .SH NAME line immediately below!
.SH NAME
is \- test argument to see if it is a class or an object
.SH SYNOPSIS
\fBis \fIoption\fR ?\fIarg arg ...\fR?
.BE

.SH DESCRIPTION
.PP
The \fBis\fR command is used to check if the argument given is
a class or an object; depending on the option given. If the argument
if a class or object, then 1 is returned. Otherwise, 0 is returned.
The \fBis\fR command also recognizes the commands wrapped in the
itcl \fBcode command.
.PP
The \fIoption\fR argument determines what action is carried out
by the command.  The legal \fIoptions\fR (which may be abbreviated)
are:
.TP
\fBis class \fIcommand\fR
Returns 1 if command is a class, and returns 0 otherwise.
.sp
The fully qualified name of the class needs to be given as the \fIcommand\fR
argument. So, if a class resides in a namespace, then the namespace needs to
be specified as well. So, if a class \fBC resides in a namespace \fBN, then 
the command should be called like:
.CS
\fBis N::C\fR
    or
\fBis ::N::C\fR
.CE
.TP
\fBis\fR object ?\fB-class \fIclassName\fR? \fIcommand\fR
Returns 1 if \fIcommand\fR is an object, and returns 0 otherwise.
.sp
If the optional "\fB-class\fR" parameter is specified, then the
\fIcommand\fR will be checked within the context of the class
given. Note that \fIclassName\fR has to exist. If not, then an
error will be given. So, if \fIclassName\fR is uncertain to be
a class, then the programmer will need to check it's existance
beforehand, or wrap it in a catch statement.
.sp
So, if \fBc\fR is an object in the class \fBC\fR, in namespace N then
these are the possibilities (all return 1):
.CS
set obj [N::C c]
is object N::c
is object c
is object $obj
is object [code c]
.CE

.SH KEYWORDS
class, object

