source: [view]
define("dojo/_base/connect", ["dojo/lib/kernel", "dojo/_base/lang"], function(dojo){
// this file courtesy of the TurboAjax Group, licensed under a Dojo CLA
// low-level delegation machinery
dojo._listener = {
// create a dispatcher function
getDispatcher: function(){
// following comments pulled out-of-line to prevent cloning them
// in the returned function.
// - indices (i) that are really in the array of listeners (ls) will
// not be in Array.prototype. This is the 'sparse array' trick
// that keeps us safe from libs that take liberties with built-in
// objects
// - listener is invoked with current scope (this)
return function(){
var ap = Array.prototype, c = arguments.callee, ls = c._listeners, t = c.target,
// return value comes from original target function
r = t && t.apply(this, arguments),
// make local copy of listener array so it is immutable during processing
i, lls = [].concat(ls)
;
// invoke listeners after target function
for(i in lls){
if(!(i in ap)){
lls[i].apply(this, arguments);
}
}
// return value comes from original target function
return r;
};
},
// add a listener to an object
add: function(/*Object*/ source, /*String*/ method, /*Function*/ listener){
// Whenever 'method' is invoked, 'listener' will have the same scope.
// Trying to supporting a context object for the listener led to
// complexity.
// Non trivial to provide 'once' functionality here
// because listener could be the result of a dojo.hitch call,
// in which case two references to the same hitch target would not
// be equivalent.
source = source || dojo.global;
// The source method is either null, a dispatcher, or some other function
var f = source[method];
// Ensure a dispatcher
if(!f || !f._listeners){
var d = dojo._listener.getDispatcher();
// original target function is special
d.target = f;
// dispatcher holds a list of listeners
d._listeners = [];
// redirect source to dispatcher
f = source[method] = d;
}
// The contract is that a handle is returned that can
// identify this listener for disconnect.
//
// The type of the handle is private. Here is it implemented as Integer.
// DOM event code has this same contract but handle is Function
// in non-IE browsers.
//
// We could have separate lists of before and after listeners.
return f._listeners.push(listener); /*Handle*/
},
// remove a listener from an object
remove: function(/*Object*/ source, /*String*/ method, /*Handle*/ handle){
var f = (source || dojo.global)[method];
// remember that handle is the index+1 (0 is not a valid handle)
if(f && f._listeners && handle--){
delete f._listeners[handle];
}
}
};
// Multiple delegation for arbitrary methods.
// This unit knows nothing about DOM, but we include DOM aware documentation
// and dontFix argument here to help the autodocs. Actual DOM aware code is in
// event.js.
dojo.connect = function(/*Object|null*/ obj,
/*String*/ event,
/*Object|null*/ context,
/*String|Function*/ method,
/*Boolean?*/ dontFix){
// summary:
// `dojo.connect` is the core event handling and delegation method in
// Dojo. It allows one function to "listen in" on the execution of
// any other, triggering the second whenever the first is called. Many
// listeners may be attached to a function, and source functions may
// be either regular function calls or DOM events.
//
// description:
// Connects listeners to actions, so that after event fires, a
// listener is called with the same arguments passed to the original
// function.
//
// Since `dojo.connect` allows the source of events to be either a
// "regular" JavaScript function or a DOM event, it provides a uniform
// interface for listening to all the types of events that an
// application is likely to deal with though a single, unified
// interface. DOM programmers may want to think of it as
// "addEventListener for everything and anything".
//
// When setting up a connection, the `event` parameter must be a
// string that is the name of the method/event to be listened for. If
// `obj` is null, `dojo.global` is assumed, meaning that connections
// to global methods are supported but also that you may inadvertently
// connect to a global by passing an incorrect object name or invalid
// reference.
//
// `dojo.connect` generally is forgiving. If you pass the name of a
// function or method that does not yet exist on `obj`, connect will
// not fail, but will instead set up a stub method. Similarly, null
// arguments may simply be omitted such that fewer than 4 arguments
// may be required to set up a connection See the examples for details.
//
// The return value is a handle that is needed to
// remove this connection with `dojo.disconnect`.
//
// obj:
// The source object for the event function.
// Defaults to `dojo.global` if null.
// If obj is a DOM node, the connection is delegated
// to the DOM event manager (unless dontFix is true).
//
// event:
// String name of the event function in obj.
// I.e. identifies a property `obj[event]`.
//
// context:
// The object that method will receive as "this".
//
// If context is null and method is a function, then method
// inherits the context of event.
//
// If method is a string then context must be the source
// object object for method (context[method]). If context is null,
// dojo.global is used.
//
// method:
// A function reference, or name of a function in context.
// The function identified by method fires after event does.
// method receives the same arguments as the event.
// See context argument comments for information on method's scope.
//
// dontFix:
// If obj is a DOM node, set dontFix to true to prevent delegation
// of this connection to the DOM event manager.
//
// example:
// When obj.onchange(), do ui.update():
// | dojo.connect(obj, "onchange", ui, "update");
// | dojo.connect(obj, "onchange", ui, ui.update); // same
//
// example:
// Using return value for disconnect:
// | var link = dojo.connect(obj, "onchange", ui, "update");
// | ...
// | dojo.disconnect(link);
//
// example:
// When onglobalevent executes, watcher.handler is invoked:
// | dojo.connect(null, "onglobalevent", watcher, "handler");
//
// example:
// When ob.onCustomEvent executes, customEventHandler is invoked:
// | dojo.connect(ob, "onCustomEvent", null, "customEventHandler");
// | dojo.connect(ob, "onCustomEvent", "customEventHandler"); // same
//
// example:
// When ob.onCustomEvent executes, customEventHandler is invoked
// with the same scope (this):
// | dojo.connect(ob, "onCustomEvent", null, customEventHandler);
// | dojo.connect(ob, "onCustomEvent", customEventHandler); // same
//
// example:
// When globalEvent executes, globalHandler is invoked
// with the same scope (this):
// | dojo.connect(null, "globalEvent", null, globalHandler);
// | dojo.connect("globalEvent", globalHandler); // same
// normalize arguments
var a=arguments, args=[], i=0;
// if a[0] is a String, obj was omitted
args.push(dojo.isString(a[0]) ? null : a[i++], a[i++]);
// if the arg-after-next is a String or Function, context was NOT omitted
var a1 = a[i+1];
args.push(dojo.isString(a1)||dojo.isFunction(a1) ? a[i++] : null, a[i++]);
// absorb any additional arguments
for(var l=a.length; i // do the actual work
return dojo._connect.apply(this, args); /*Handle*/
}
// used by non-browser hostenvs. always overriden by event.js
dojo._connect = function(obj, event, context, method){
var l=dojo._listener, h=l.add(obj, event, dojo.hitch(context, method));
return [obj, event, h, l]; // Handle
};
dojo.disconnect = function(/*Handle*/ handle){
// summary:
// Remove a link created by dojo.connect.
// description:
// Removes the connection between event and the method referenced by handle.
// handle:
// the return value of the dojo.connect call that created the connection.
if(handle && handle[0] !== undefined){
dojo._disconnect.apply(this, handle);
// let's not keep this reference
delete handle[0];
}
};
dojo._disconnect = function(obj, event, handle, listener){
listener.remove(obj, event, handle);
};
// topic publish/subscribe
dojo._topics = {};
dojo.subscribe = function(/*String*/ topic, /*Object|null*/ context, /*String|Function*/ method){
// summary:
// Attach a listener to a named topic. The listener function is invoked whenever the
// named topic is published (see: dojo.publish).
// Returns a handle which is needed to unsubscribe this listener.
// context:
// Scope in which method will be invoked, or null for default scope.
// method:
// The name of a function in context, or a function reference. This is the function that
// is invoked when topic is published.
// example:
// | dojo.subscribe("alerts", null, function(caption, message){ alert(caption + "\n" + message); });
// | dojo.publish("alerts", [ "read this", "hello world" ]);
// support for 2 argument invocation (omitting context) depends on hitch
return [topic, dojo._listener.add(dojo._topics, topic, dojo.hitch(context, method))]; /*Handle*/
};
dojo.unsubscribe = function(/*Handle*/ handle){
// summary:
// Remove a topic listener.
// handle:
// The handle returned from a call to subscribe.
// example:
// | var alerter = dojo.subscribe("alerts", null, function(caption, message){ alert(caption + "\n" + message); };
// | ...
// | dojo.unsubscribe(alerter);
if(handle){
dojo._listener.remove(dojo._topics, handle[0], handle[1]);
}
};
dojo.publish = function(/*String*/ topic, /*Array*/ args){
// summary:
// Invoke all listener method subscribed to topic.
// topic:
// The name of the topic to publish.
// args:
// An array of arguments. The arguments will be applied
// to each topic subscriber (as first class parameters, via apply).
// example:
// | dojo.subscribe("alerts", null, function(caption, message){ alert(caption + "\n" + message); };
// | dojo.publish("alerts", [ "read this", "hello world" ]);
// Note that args is an array, which is more efficient vs variable length
// argument list. Ideally, var args would be implemented via Array
// throughout the APIs.
var f = dojo._topics[topic];
if(f){
f.apply(this, args||[]);
}