NAME

       callback, mymethod - generate callbacks to methods

SYNOPSIS

       package require tcl::oo

       callback methodName ?arg ...?
       mymethod methodName ?arg ...?
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DESCRIPTION

       The callback command, also called mymethod for compatibility with the ooutil and snit packages of Tcllib,
       and  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 generate a  script  fragment  that  will  invoke  the  method,
       methodName,  on the current object (as reported by self) when executed. Any additional arguments provided
       will be provided as leading arguments to the callback. The resulting script fragment shall  be  a  proper
       list.

       Note  that  it  is  up  to  the  caller  to  ensure that the current object is able to handle the call of
       methodName; this command does not check that.  methodName may refer to any exported or unexported method,
       but may not refer to a private method as those can only be invoked directly from within methods. If there
       is no such method present at the point when the callback is invoked, the standard unknown method  handler
       will be called.

EXAMPLE

       This  is  a  simple  echo  server  class.  The callback command is used in two places, to arrange for the
       incoming socket connections to be handled by the Accept method, and to arrange for the incoming bytes  on
       those connections to be handled by the Receive method.

              oo::class create EchoServer {
                  variable server clients
                  constructor {port} {
                      set server [socket -server [callback Accept] $port]
                      set clients {}
                  }
                  destructor {
                      chan close $server
                      foreach client [dict keys $clients] {
                          chan close $client
                      }
                  }

                  method Accept {channel clientAddress clientPort} {
                      dict set clients $channel [dict create \
                              address $clientAddress port $clientPort]
                      chan event $channel readable [callback Receive $channel]
                  }
                  method Receive {channel} {
                      if {[chan gets $channel line] >= 0} {
                          my echo $channel $line
                      } else {
                          chan close $channel
                          dict unset clients $channel
                      }
                  }

                  method echo {channel line} {
                      dict with clients $channel {
                          chan puts $channel \
                                  [format {[%s:%d] %s} $address $port $line]
                      }
                  }
              }

SEE ALSO

       chan(3tcl), fileevent(3tcl), my(3tcl), self(3tcl), socket(3tcl), trace(3tcl)

KEYWORDS

       callback, object

TclOO                                                  0.3                                        callback(3tcl)