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Updated: Thursday, June 13, 2019
 
 

oo_class (1t)

Name

oo_class - class of all classes

Synopsis

package require TclOO

oo::class method ?arg ...?

Description

class(1t)                       TclOO Commands                       class(1t)



______________________________________________________________________________

NAME
       oo::class - class of all classes

SYNOPSIS
       package require TclOO

       oo::class method ?arg ...?

CLASS HIERARCHY
       oo::object
          -> oo::class
______________________________________________________________________________

DESCRIPTION
       Classes  are  objects that can manufacture other objects according to a
       pattern stored in the factory object (the class). An  instance  of  the
       class  is  created by calling one of the class's factory methods, typi-
       cally either create if an explicit name is being given, or  new  if  an
       arbitrary unique name is to be automatically selected.

       The  oo::class  class  is  the  class of all classes; every class is an
       instance of this class, which is consequently an  instance  of  itself.
       This  class  is  a  subclass  of  oo::object, so every class is also an
       object.  Additional metaclasses  (i.e.,  classes  of  classes)  can  be
       defined  if necessary by subclassing oo::class. Note that the oo::class
       object hides the new method on itself, so new classes should always  be
       made using the create method.

   CONSTRUCTOR
       The  constructor  of  the  oo::class  class  takes an optional argument
       which, if present, is sent to the oo::define command  (along  with  the
       name  of the newly-created class) to allow the class to be conveniently
       configured at creation time.

   DESTRUCTOR
       The oo::class class does not define an  explicit  destructor.  However,
       when  a  class  is destroyed, all its subclasses and instances are also
       destroyed, along with all objects that it has been mixed into.

   EXPORTED METHODS
       cls create name ?arg ...?
              This creates a new instance of the class cls called name  (which
              is  resolved within the calling context's namespace if not fully
              qualified), passing the arguments, arg ..., to the  constructor,
              and  (if  that  returns a successful result) returning the fully
              qualified name of the created object (the  result  of  the  con-
              structor  is ignored). If the constructor fails (i.e.  returns a
              non-OK result) then the object is destroyed and the  error  mes-
              sage is the result of this method call.

       cls new ?arg ...?
              This  creates  a new instance of the class cls with a new unique
              name, passing the arguments, arg ..., to  the  constructor,  and
              (if that returns a successful result) returning the fully quali-
              fied name of the created object (the result of  the  constructor
              is  ignored).  If  the constructor fails (i.e., returns a non-OK
              result) then the object is destroyed and the  error  message  is
              the result of this method call.

              Note  that  this  method is not exported by the oo::class object
              itself, so classes should not be created using this method.

   NON-EXPORTED METHODS
       The oo::class class supports the following non-exported methods:

       cls createWithNamespace name nsName ?arg ...?
              This creates a new instance of the class cls called name  (which
              is  resolved within the calling context's namespace if not fully
              qualified), passing the arguments, arg ..., to the  constructor,
              and  (if  that  returns a successful result) returning the fully
              qualified name of the created object (the  result  of  the  con-
              structor is ignored). The name of the instance's internal names-
              pace will be nsName unless that namespace already  exists  (when
              an  arbitrary  name  will be chosen instead). If the constructor
              fails (i.e.,  returns  a  non-OK  result)  then  the  object  is
              destroyed  and  the  error  message is the result of this method
              call.

EXAMPLES
       This example defines  a  simple  class  hierarchy  and  creates  a  new
       instance  of it. It then invokes a method of the object before destroy-
       ing the hierarchy and showing that the destruction is transitive.

              oo::class create fruit {
                  method eat {} {
                      puts "yummy!"
                  }
              }
              oo::class create banana {
                  superclass fruit
                  constructor {} {
                      my variable peeled
                      set peeled 0
                  }
                  method peel {} {
                      my variable peeled
                      set peeled 1
                      puts "skin now off"
                  }
                  method edible? {} {
                      my variable peeled
                      return $peeled
                  }
                  method eat {} {
                      if {![my edible?]} {
                          my peel
                      }
                      next
                  }
              }
              set b [banana new]
              $b eat               -> prints "skin now off" and "yummy!"
              fruit destroy
              $b eat               -> error "unknown command"


ATTRIBUTES
       See attributes(7) for descriptions of the following attributes:


       +---------------+------------------+
       |ATTRIBUTE TYPE | ATTRIBUTE VALUE  |
       +---------------+------------------+
       |Availability   | runtime/tcl-8    |
       +---------------+------------------+
       |Stability      | Uncommitted      |
       +---------------+------------------+
SEE ALSO
       oo::define(n), oo::object(n)

KEYWORDS
       class, metaclass, object



NOTES
       This    software    was    built    from    source     available     at
       https://github.com/oracle/solaris-userland.    The  original  community
       source was downloaded from  http://prdownloads.sourceforge.net/tcl/tcl-
       core8.6.7-src.tar.gz

       Further information about this software can be found on the open source
       community website at https://www.tcl.tk/.



TclOO                                 0.1                            class(1t)