The strawman articles on Object Initialisers look very promising (
http://wiki.ecmascript.org/doku.php?id=strawman:object_initialiser_extensions),
but one issue I didn't see discussed is a solution to enable the inheritance
of privileged members. Currently developers have to redefine accessor
properties and methods on every constructor call to maintain a reference to
the instance private variables. Ex:
----------------------------------------------------------------
function Foo(name, value){
// assume there was argument validation of some form.
var _name = name,
_value = value;
this.__defineGetter__("name", function(){
return _name;
});
this.__defineSetter__("name", function(v){
//[snip] argument validation
_name = v;
});
this.__defineGetter__("value", function(){
return _value;
});
this.__defineSetter__("value", function(v){
//[snip] argument validation
_value= v;
});
this.toString = function(){
return _name + ":" + _value";
}
}
----------------------------------------------------------------
This approach can obviously leads to a potentially large amount of memory
consumption. One workaround I've discovered to solve this issue is a pattern
like the following:
----------------------------------------------------------------
var Foo = (function(){
var _refs = [],
_props = [],
_private = {
get : function(o,n){
var i = _refs.indexOf(o);
return ~i ? _props[i][n] : undefined;
},
set : function(o,n,v){
var i = _refs.indexOf(o);
if(~i)
_props[i][n] = v;
var len = _refs.length;
_refs[len] = o;
_props[len] = {};
_props[len][n] = v;
}
};
function Foo(name, value){
_private.set(this, "name", name);
_private.set(this, "value", value);
}
Foo.prototype = {
get name(){
return _private.get(this, "name");
},
set name(v){
_private.set(this, "name", v);
},
get value(){
return _private.get(this, "value");
},
set value(v){
_private.set(this, "value", v);
},
toString : function(){
return _private.get(this,"name") + ":" + _private.get(this,
"value")
}
}
return Foo;
})();
----------------------------------------------------------------
The verbosity is apparent. Has there been any discussion with Object
Initialisers related to this type of problem?
Respectfully,
Michael Haufe
_______________________________________________
es-discuss mailing list
[email protected]
https://mail.mozilla.org/listinfo/es-discuss
