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is(n)                                            [incr Tcl]                                            is(n)



NAME
       is - test argument to see if it is a class or an object

SYNOPSIS
       is option ?arg arg ...?


DESCRIPTION
       The  is  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 is command also recognizes the commands wrapped in the itcl code command.

       The  option  argument determines what action is carried out by the command.  The legal options (which
       may be abbreviated) are:

       is class command
              Returns 1 if command is a class, and returns 0 otherwise.

              The fully qualified name of the class needs to be given as the  command  argument.  So,  if  a
              class resides in a namespace, then the namespace needs to be specified as well. So, if a class
              C resides in a namespace N, then the command should be called like: is N::C
                  or is ::N::C

       is object ?-class className? command
              Returns 1 if command is an object, and returns 0 otherwise.

              If the optional "-class" parameter is specified, then the command will be checked  within  the
              context  of  the  class given. Note that className has to exist. If not, then an error will be
              given. So, if className is uncertain to be a class, then the programmer  will  need  to  check
              it's existance beforehand, or wrap it in a catch statement.

              So,  if  c  is  an object in the class C, in namespace N then these are the possibilities (all
              return 1): set obj [N::C c] is object N::c is object c is object $obj is object [code c]


KEYWORDS
       class, object




itcl                                                 3.3                                               is(n)