[comment {-*- tcl -*- doctools manpage}]
[manpage_begin tcl::chan::events n 1.1]
[keywords {event management}]
[keywords {reflected channel}]
[keywords {tip 219}]
[keywords {virtual channel}]
[copyright {2009 Andreas Kupries <andreas_kupries@users.sourceforge.net>}]
[moddesc   {Reflected/virtual channel support}]
[category  Channels]
[titledesc {Event support for reflected/virtual channels}]
[require Tcl "8.5 9"]
[require TclOO]
[require tcl::chan::core [opt 1.1]]
[require tcl::chan::events [opt 1.1]]
[description]
[para]

The [package tcl::chan::events] package provides a [package TclOO]
class implementing common behaviour needed by virtually every
reflected or virtual channel supporting event driven IO. It is a
sub-class of [package tcl::chan::core], inheriting all of its behaviour.

[para] This class expects to be used as either superclass of a concrete
channel class, or to be mixed into such a class.

[section {Class API}]

[list_begin definitions]

[call [cmd ::tcl::chan::events] [arg objectName]]

This command creates a new channel event core object with an associated
global Tcl command whose name is [emph objectName]. This command may
be used to invoke various operations on the object, as described in
the section for the [sectref {Instance API}].

[list_end]

[section {Instance API}]

The API of channel event core instances provides only four methods, two
corresponding to channel handler commands (For reference see
[uri http:/tip.tcl.tk/219 {TIP 219}]), and the other two for use by
sub-classes to control event generation. They former expect to be called
from whichever object instance the channel event core was made a part of.

[list_begin definitions]

[call [arg objectName] [method finalize] [arg thechannel]]

This method implements standard behaviour for the [method finalize]
method of channel handlers. It overrides the behaviour inherited from
[package tcl::chan::core] and additionally disables any and all event
generation before destroying itself.

[call [arg objectName] [method watch] [arg thechannel] [arg eventmask]]

This method implements standard behaviour for the [method watch]
method of channel handlers. Called by the IO system whenever the
interest in event changes it updates the instance state to activate
and/or suppress the generation of the events of (non-)interest.

[call [arg objectName] [method allow] [arg eventname]...]
[call [arg objectName] [method disallow] [arg eventname]...]

These two methods are exported to sub-classes, so that their instances
can notify their event core of the events the channel they implement
can (allow) or cannot (disallow) generate.

Together with the information about the events requested by Tcl's IO
system coming in through the [method watch] method the event core is
able to determine which events it should (not) generate and act
accordingly.

[list_end]

[vset CATEGORY virtchannel]
[include ../common-text/feedback.inc]
[manpage_end]
