NAME

       self - method call internal introspection

SYNOPSIS

       package require TclOO

       self ?subcommand?
_________________________________________________________________________________________________

DESCRIPTION

       The  self command, which should only be used from within the context of a call to a method
       (i.e. inside a method, constructor or destructor body) is used  to  allow  the  method  to
       discover information about how it was called. It takes an argument, subcommand, that tells
       it what sort of information is actually desired; if omitted the result will be the same as
       if self object was invoked. The supported subcommands are:

       self call
              This  returns  a  two-element  list  describing  the method implementations used to
              implement the current call chain. The  first  element  is  the  same  as  would  be
              reported  by info object call for the current method (except that this also reports
              useful values from within constructors and destructors, whose names are reported as
              <constructor>  and  <destructor>  respectively), and the second element is an index
              into the first  element's  list  that  indicates  which  actual  implementation  is
              currently executing (the first implementation to execute is always at index 0).

       self caller
              When  the  method  was  invoked  from inside another object method, this subcommand
              returns a three element list describing the containing object and method. The first
              element  describes  the declaring object or class of the method, the second element
              is the name of the object on which the containing method was invoked, and the third
              element  is the name of the method (with the strings <constructor> and <destructor>
              indicating constructors and destructors respectively).

       self class
              This returns the name of the class that the  current  method  was  defined  within.
              Note that this will change as the chain of method implementations is traversed with
              next, and that if the method was defined on an object then this will fail.

              If you want the class of the current object, you need to use this other construct:

                     info object class [self object]

       self filter
              When invoked inside  a  filter,  this  subcommand  returns  a  three  element  list
              describing the filter. The first element gives the name of the object or class that
              declared the filter (note that this may be different from the object or class  that
              provided  the implementation of the filter), the second element is either object or
              class depending on whether the declaring entity was an object  or  class,  and  the
              third element is the name of the filter.

       self method
              This  returns  the  name  of the current method (with the strings <constructor> and
              <destructor> indicating constructors and destructors respectively).

       self namespace
              This returns the name of the unique namespace of the object  that  the  method  was
              invoked upon.

       self next
              When  invoked  from a method that is not at the end of a call chain (i.e. where the
              next command will invoke an actual method implementation), this subcommand  returns
              a  two element list describing the next element in the method call chain; the first
              element is the name of the class or object that declares the next part of the  call
              chain,  and  the  second  element  is  the  name  of  the  method (with the strings
              <constructor>   and   <destructor>   indicating   constructors   and    destructors
              respectively).  If  invoked  from a method that is at the end of a call chain, this
              subcommand returns the empty string.

       self object
              This returns the name of the object that the method was invoked upon.

       self target
              When invoked inside a filter implementation, this subcommand returns a two  element
              list  describing  the  method being filtered. The first element will be the name of
              the declarer of the method, and the second element will be the actual name  of  the
              method.

EXAMPLES

       This example shows basic use of self to provide information about the current object:

              oo::class create c {
                  method foo {} {
                      puts "this is the [self] object"
                  }
              }
              c create a
              c create b
              a foo                → prints "this is the ::a object"
              b foo                → prints "this is the ::b object"

       This demonstrates what a method call chain looks like, and how traversing along it changes
       the index into it:

              oo::class create c {
                  method x {} {
                      puts "Cls: [self call]"
                  }
              }
              c create a
              oo::objdefine a {
                  method x {} {
                      puts "Obj: [self call]"
                      next
                      puts "Obj: [self call]"
                  }
              }
              a x     → Obj: {{method x object method} {method x ::c method}} 0
                      → Cls: {{method x object method} {method x ::c method}} 1
                      → Obj: {{method x object method} {method x ::c method}} 0

SEE ALSO

       info(3tcl), next(3tcl)

KEYWORDS

       call, introspection, object