Hi, It's unclear whether you're talking about removing the `namespace.Popup` *class* (well, constructor function -- JavaScript doesn't have classes), or removing the `popup` *instance* (object) that you've created for a specific popover.
The short version: If you want to remove the instance you created in `rollever`, what you're doing is mostly fine although there's probably a bug in the quoted code. (You have an extra `var` in the line `var popup = new Popup()` which makes it shadow the variable you declare in the containing scope; as a result, it's eligible for GC as soon as `rollever` returns. Probably just a typo in the quick pseudo-code.) The long version: To release the memory associated with an object (or a primitive, for that matter), all you do is make sure nothing is referring to it anymore. JavaScript is a garbage-collected language, you don't release memory explicitly. You just make sure that nothing refers to the thing you want to get rid of, and eventually the garbage collector will notice that it's unreferenced and will remove it from memory. (When and how it does this is entirely up to the JavaScript implementation, some implementations are quite lazy, others are more pro-active.) You do that in one of four ways: 1. If the thing is referenced from a `var` (`var popup = new Popup();`), assign `undefined` to the `var` (`null` is also fine as you've done in `rollout`). I use `undefined` because it's symmetrical: `undefined` is the value a `var` has before you assign anything to it, so it makes sense to me that to "clear" it I put it back in that same state). But you see `null` used a lot, probably because it's short and easy to type and similar to the null concept in other languages, and there's nothing wrong with it if you don't obsess about symmetry like I do. 2. If the thing is a property on an object and you're done with the property, either A) assign `undefined` (or `null`) to the property (the object will still have the property but the property's value will be `undefined` [or `null`]), or B) completely remove the property from the object via `delete` (the object will no longer have the property at all). `delete` looks like this: delete foo.bar; // or delete foo["bar"]; // the string can be a literal, or any expression resulting in a string (Important: `delete` removes a property from an object. It has *nothing* to do with memory management, except as a side-effect -- if the property being removed was the last thing to reference something. It is nothing whatsoever like `delete` in C++ or some other languages.) 3. If the thing is a property on an object (like your `Popup` property on your `namespace` object), if you're done with the object as a whole, just release the object as a whole. Anything the object's properties referred to will get cleaned up if those are the only remaining references. E.g., when releasing `namespace`, you don't have to go through releasing all of its properties first. 4. If it's referenced from a `var` within a function, and you don't create any closures[1] (functions) within the function, just let the function return. If that `var` is the only thing referring to the thing you're trying to release, the reference will get cleaned up when the `var` is. (JavaScript nerds like me will point out that this is the same as #3 above, because behind the scenes, `var`s in functions are actually properties of an object that gets cleaned up when the function returns unless a closure has a reference to it.) Mind you, depending on what `Popup` does, you may not need to keep a copy of the instance at all. If it hooks up handlers to events or something, those references will keep it in memory until you unhook it. [1] http://blog.niftysnippets.org/2008/02/closures-are-not-complicated.html FWIW, -- T.J. Crowder Independent Software Engineer tj / crowder software / com www / crowder software / com On Aug 23, 6:56 pm, chapster <emurra...@gmail.com> wrote: > When I create a class like example below. How would I remove a class > so its not in memory. > > namespace.Popup = Class.create( > { > initialize: function(params){ > ... > }, > > show:function(){ > // create or show > } > > }); > > I was thinking of creating this at the start of my application and > just hiding and showing the popup which will be a div that will be > passed into the popup class as a container. > > In other languages I have called the class everytime a user rolls over > an element like below. > > //pseudo code > > var popup; > > function rollever(){ > var popup = new Popup(); > popup.show(); > > } > > function rollout(){ > if (popup) popup = null; > > } > > How would you remove a class like above in prototype. -- You received this message because you are subscribed to the Google Groups "Prototype & script.aculo.us" group. To post to this group, send email to prototype-scriptaculous@googlegroups.com. To unsubscribe from this group, send email to prototype-scriptaculous+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/prototype-scriptaculous?hl=en.
