class:: CmdPeriod
summary:: register objects to be cleared when Cmd-. is pressed
related:: Classes/ShutDown, Classes/ServerQuit
categories:: Control

description::

CmdPeriod allows you to register objects to perform an action when the user presses Cmd-. These objects must implement a method called strong::-cmdPeriod:: which performs the necessary tasks. (You can add such a method in your custom classes.) Note that since link::Classes/Function:: implements strong::-cmdPeriod:: as a synonym for strong::-value::, it is possible to register any function (and thus any arbitrary code) for evaluation when Cmd-. is pressed.

ClassMethods::

method::add
Registers an object to be cleared when Cmd-. is pressed. This object will stay registered until it is explicitly removed, and will thus respond to additional presses of Cmd-.

method::remove
Removes an object that was previously registered.

method::removeAll
Removes all objects that have been registered.

method::doOnce
Registers an object to be evaluated once, and then unregistered.

method::objects
Get or set the list of objects that are called when CmdPeriod is evaluated.

method::era
The number of times CmdPeriod has been called since startup.

Examples::

code::
(
f = {"foo".postln };
g = {"bar".postln };
CmdPeriod.add(f);
CmdPeriod.add(g);
)

// Now press Cmd-.

CmdPeriod.remove(g);

// Now press Cmd-. Only f executes

CmdPeriod.remove(f); // must explicitly cleanup


// Now press Cmd-.

CmdPeriod.add(g); // one object is added only once.
CmdPeriod.add(g); // one object is added only once.


// Now press Cmd-.

// remove it again.
CmdPeriod.remove(g);


// note that often you want to automatically remove the function once it is evaluated
// instead of

f = { "foo".postln; CmdPeriod.remove(f) };
CmdPeriod.add(f);

// you can write:

CmdPeriod.doOnce { "foo".postln }

// a typical example:
(
w = Window.new("close on cmd-.").front;
CmdPeriod.doOnce { w.close };
)


// in some cases you might need to defer the function by a short amount of time
a = { Synth(\default)};
a.value;
CmdPeriod.add({{a.value}.defer(0.01)});

// remove all
CmdPeriod.removeAll

::