Use expression binding for rz-slider-options

[rabbitfang]

The current code uses two-way binding for the slider options, which can cause infinite digest loops (see https://jsfiddle.net/txupy024/). The slider code never modifies the options value, so the two way binding is not needed.

The fix is a two line change, and I would be able to make the contribution myself.

[ValentinH]

I think that it is not a good practice to set a function that return an object. You should bind to an object directly since it is easier to check for the $digest cycle. With expression binding, can you set callbacks such as onChange or onStart?

[rabbitfang]

I think that it is not a good practice to set a function that return an object.

The function will not necessarily return a new object for every invocation. The function's body could just a single line, perhaps using a parameter to change the return value. For example,

$scope.getSliderOptions = function(category) {
  return categoryService.getInfo(category).sliderOptions;
}

Permitting expressions also allows usage such as

<div ng-repeat="category in categories">
  <h1>{{category}}</h1>
  <rzslider
    rz-slider-model="values[category]"
    rz-slider-options="options[category] || defaultOptions"></rzslider>
</div>

You should bind to an object directly since it is easier to check for the $digest cycle.

Yes, binding directly to an object would be best, but it is not always the best option.

With expression binding, can you set callbacks such as onChange or onStart?

Yes. Any time that angular detects a change in the options, the applyOptions function is called, which updates the internal copy of the options which includes the onChange and onStart callbacks. The rzslider directive does not store a reference to the options itself anyways, but instead makes a copy so that it can use default options properly.

[ValentinH]

Well I'm not sure of how to implement what you are talking about so if you can submit a PR that passes all the unit tests, I could better understand.

[rabbitfang]

Could a release be made that includes #266 please? This issue is blocking my project.

[ValentinH]

Yes I'll do it when I get the time. If you want to prepare the job, you can submit a PR with the bower/npm version updated, the dist files generated and the Changelog. Thanks to this I'll only need to create a tag and call npm publish.

[rabbitfang]

Release PR created in #271