Re: Object.prototype.clone
I have clone objects like this:
//
function cloneObject( srcObj ) {
if( srcObj == null ) { return srcObj; } //undefined or null
var newObject;
switch( typeof(srcObj) ) {
case object:
newObject = new srcObj.constructor();
for( var property in srcObj ) {
//Do not clone inherited values
if( srcObj.hasOwnProperty(property) || typeof( srcObj[property] ) ===
'object' ) {
newObject[property]= cloneObject( srcObj[property] );
}
}
break;
default:
newObject = srcObj;
break;
}
return newObject;
}
- Original Message -
From: Peter Michaux [EMAIL PROTECTED]
To: es4-discuss@mozilla.org
Sent: Monday, October 22, 2007 5:07 AM
Subject: Object.prototype.clone
Hi,
Is there a plan for a clone function in ES4?
Object.prototype.clone = function() {
function F() {}
F.prototype = o;
return new F();
};
The earliest reference I have found to this function is a post by
Lasse Reichstein Nielsen in 2003 on comp.lang.javascript
http://groups.google.com/group/comp.lang.javascript/msg/5d06e72e55d5bf11
In the past year this function has been evangelized by Douglas Crockford.
http://javascript.crockford.com/prototypal.html
Given the idea has persisted for at least a four year period as
something useful in a prototype-based language, would a clone function
be a good addition to the language itself?
Peter
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Re: Object.prototype.clone
cloneObject( this ); // Error if this is window.
// enumeration is partially broken in IE, this loop will sometimes fail
for( var property in srcObj )
On 10/22/07, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote:
I have clone objects like this:
//
function cloneObject( srcObj ) {
if( srcObj == null ) { return srcObj; } //undefined or null
var newObject;
switch( typeof(srcObj) ) {
case object:
newObject = new srcObj.constructor();
for( var property in srcObj ) {
//Do not clone inherited values
if( srcObj.hasOwnProperty(property) || typeof( srcObj[property] ) ===
'object' ) {
newObject[property]= cloneObject( srcObj[property] );
}
}
break;
default:
newObject = srcObj;
break;
}
return newObject;
}
- Original Message -
From: Peter Michaux [EMAIL PROTECTED]
To: es4-discuss@mozilla.org
Sent: Monday, October 22, 2007 5:07 AM
Subject: Object.prototype.clone
Hi,
Is there a plan for a clone function in ES4?
Object.prototype.clone = function() {
function F() {}
F.prototype = o;
return new F();
};
The earliest reference I have found to this function is a post by
Lasse Reichstein Nielsen in 2003 on comp.lang.javascript
http://groups.google.com/group/comp.lang.javascript/msg/5d06e72e55d5bf11
In the past year this function has been evangelized by Douglas Crockford.
http://javascript.crockford.com/prototypal.html
Given the idea has persisted for at least a four year period as
something useful in a prototype-based language, would a clone function
be a good addition to the language itself?
Peter
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Re: Object.prototype.clone
On 10/21/07, Peter Michaux [EMAIL PROTECTED] wrote:
Hi,
Is there a plan for a clone function in ES4?
Object.prototype.clone = function() {
function F() {}
F.prototype = o;
return new F();
};
The earliest reference I have found to this function is a post by
Lasse Reichstein Nielsen in 2003 on comp.lang.javascript
http://groups.google.com/group/comp.lang.javascript/msg/5d06e72e55d5bf11
In the past year this function has been evangelized by Douglas Crockford.
I had the misfortune of working on code that uses this pattern while
at Yahoo. Since Yahoo pretty much shuns testing and my boss didn't
really like me refactoring code, my debugging skills improved. What
mess of code. I still remember the code object. 1100+ line module
pattern
YAHOO.mst.app.code = (function(){
// 1100+ lines...
return {
};
})_
The guys would sometimes get confused and reassign the namespace to a
variable, too.
YAHOO.namespace(mst.app.code);
YAHOO.mst.app.code.getGlobal = function(k){};
YAHOO.mst.app.code = (function(){ // uh-oh, what happened to getGlobal?
});
An interesting device, hard to debug, confuses less-skilled
programmers, usually relies on too much anon functions/constructors.
Increases scope chain.
http://javascript.crockford.com/prototypal.html
I don't see the part about clone. Cloning brings up the issue of how deep.
Given the idea has persisted for at least a four year period as
something useful in a prototype-based language, would a clone function
be a good addition to the language itself?
A Clonable interface would be an OK addition. But cloning is tricky
when it comes to mutable objects
a = {
items : [1,2,3]
};
b = clone( a );
b.items.reverse();
a.items[0]; // 1 or 3?
How deep should clone go?
Peter
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Re: Object.prototype.clone
http://javascript.crockford.com/prototypal.html
It is the act of creating a object that inherits from/delegates to the
provided object. Peter is suggesting sugar for one of the important
mechanisms in a prototypal language. I believe the copy semantic is used
in Self. clone is bit misleading (well, I think copy is too). With
classes, we call it subclassing. We could call it subobject :). Douglas
calls it begetObjet (nice), I personally think it is very valuable
construct and I like what it encourages, but on the otherhand it is so
easy/compact to create (about 4 lines of code), and it doesn't seem to be
the direction ES4 is headed, so it's omission seems reasonable.
YAHOO.mst.app.code = (function(){
// 1100+ lines...
I don't think this doesn't have anything to do with the topic.
Kris
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Re: Object.prototype.clone
On 10/21/07, Kris Zyp [EMAIL PROTECTED] wrote:
http://javascript.crockford.com/prototypal.html
It is the act of creating a object that inherits from/delegates to the
provided object. Peter is suggesting sugar for one of the important
mechanisms in a prototypal language. I believe the copy semantic is used
in Self. clone is bit misleading (well, I think copy is too). With
classes, we call it subclassing. We could call it subobject :). Douglas
calls it begetObjet (nice), I personally think it is very valuable
construct and I like what it encourages, but on the otherhand it is so
easy/compact to create (about 4 lines of code), and it doesn't seem to be
the direction ES4 is headed, so it's omission seems reasonable.
function beget(o) {
function F() {}
F.prototype = o;
return new F();
}
var x = {
items : [1,2,3]
};
var y = beget(x);
y.items.reverse(); // reverse my y items.
x.items[0]; // What is it?
The point I made earlier about mutable objects addresses this very issue.
It's attractive, but easily breakable.
YAHOO.mst.app.code = (function(){
// 1100+ lines...
I don't think this doesn't have anything to do with the topic.
It's little off-topic. It can cause problems in real-world programming
was the point I was trying to make. Looking at Doug's side made me
remember that code and the (long, excruciating) time I spent, often @
the office until 8 or 10 on a Friday. I'm getting off topic again...
Garrett
Kris
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