make 'with' more lightweight

mbest commented 12 years ago

The 'with' binding currently uses the native template template engine, which adds a lot of overhead. The main purpose of the 'with' binding is to push a new binding context to the stack for child elements (doesn't affect any other bindings on the same element as 'with').

The current implementation also does an 'if' with the target of 'with', which I think is incorrect (doesn't match the way 'with' works in JS or in other languages). So although removing the templating code under with would remove the 'if' functionality, I thinks that it's better anyway.

'with' should still work in container-less bindings (), which would need to be modified to work with non-template bindings.

mbest commented 12 years ago

ko.bindingHandlers['withlight'] = {
    'init': function(element, valueAccessor, allBindingsAccessor, viewModel, bindingContext) {
        var bindingValue = valueAccessor();
        if (typeof bindingValue != 'object' || bindingValue === null)
            throw new Error('withlight must be used with an object');
        var innerContext = bindingContext['createChildContext'](bindingValue);
        ko.applyBindingsToDescendants(innerContext, element);
        return { 'controlsDescendantBindings': true };
    }
};

mbest commented 12 years ago

Oops. Last commit also included some unrelated changes to dependentObservable.

dotnetwise commented 12 years ago

Any chance I can use this with containerless bindings?

....

It's pretty hard to generate

elements without a container otherwise.

The "with binding" sucks, at it replaces the html itself, thus all the pre-filled values, jquery event bindings etc. will be lost!

mbest commented 12 years ago

Not at this point. It would require some changes within Knockout.

dotnetwise commented 12 years ago

Too bad :( I guess withlight should be a mandatory feature of ko Since "with" breaks any javascript plugin that would be rendered within an comment "with" binding And that's because ko replaces the DOM thus all the content, event bindings and custom jquery data is lost.

"with" makes ko unusable. It should for sure not "recreate" the DOM!

dotnetwise commented 12 years ago

Why not updating KO itself?

mbest commented 12 years ago

I've submitted a pull request for Knockout to support custom container-less binding: https://github.com/SteveSanderson/knockout/pull/290

dotnetwise commented 12 years ago

Where did the withlight binding go in the latest v2.1.0pre?

mbest commented 12 years ago

I don't think it was ever included in 2.1. I'm hoping we'll get it in as part of 2.2.

vamp commented 12 years ago

maybe withlite can be renamed to "using"?

NoelAbrahams commented 12 years ago

Please can we have this included in KO? This is a core feature and maintaining this as a custom binding outside of KO can introduce bugs.

I also vote that "using" is an appropriate name for this binding, and sounds better than "withlight", because rather than being a lighter version of "with" it is really a replacement for it. This naming would permit phasing out of "with".

mbest commented 12 years ago

I've opened an issue for the improved with: SteveSanderson/knockout#476. Feel free to add your comments there also. Ultimately, it's Steve who decides what gets included in Knockout.

dotnetwise commented 12 years ago

So what's the current status? I can't seem to be finding anything out of the box for 2.1 in the docs

mbest commented 12 years ago

So what's the current status?

We're planning to include an improved with in the upcoming version of Knockout, 2.2.

mbest commented 11 years ago

Knockout 2.2 includes a new implementation of with that does what withlight does (and everything that with did before). Check it out.

dotnetwise commented 11 years ago

Already in the docs?

mbest commented 11 years ago

We didn't update the docs for it since it's not exactly a feature. It just makes the binding work more like people expect.

dotnetwise commented 11 years ago

Will it appear in the docs? :)

dotnetwise commented 11 years ago

The above withlight works great, but it still is missing from the latest KO. For example, if you are using with: loginData on your login form then it will break your browser's autocomplete feature for the username/password. However with the withlight binding it works as exepcted. So any chance you'd add it to the main branch as well?

mbest commented 11 years ago

I'd like to see what you're talking about. Can you put together an example for me?

dotnetwise commented 11 years ago

Do you konw Durandal ? Imagine the login form is just a module that gets loaded dynamically. Of course password manager won't work. But, if you move the login form in the main html itself, then there are two cases:

with - will rewrite the markup, so you'll loose the autocompleted username/password
withlight - will work perfectly :)

mbest / knockout

make 'with' more lightweight #9