Use exposed equals inside watch and equals

[lee-elenbaas]

This will allow using the proxy pattern for providing better equals implementation for specific cases

very good when you use an existing widget that performs watch on some property that you can provide a faster way to equal check it but you want to do it without changing the widget code

[mary-poppins]

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[caitp]

I don't understand? what is the motivation for this? so that you can customize the equals function?

[lee-elenbaas]

exactly! when i know that in my SPA there are a lot of comparisons of a specific type, i can create a better comparison for that type (that depends only on the minimum number of properties that object needs. and then use the proxy pattern to replace the equals so that it will perform better for my SPA

[IgorMinar]

this doesn't look right.

we rely on equals implementation heavily at many places throughout the framework, we can't let you monkey patch it and hope for the best.

it would be better if you described your use-cases in a bug/feature issue and then we can decide how to deal with it.

[lee-elenbaas]

Of course angular depends heavily on equals - this is exactly why it is important that i will be able to enhance equals to fit better for my own SPA

Assume that there are a lot of watchs on instances of MyClass
One way to improve performance is by minimizing the number of watches. I can do this easily enough in my own code, but if i use some other library, my ability to limit the number of watch that library adds is limited. It is enough that that library will use ng-repeat on a collection containing MyClass instances that i can benefit from making equals perform better for MyClass

the proxy pattern for doing that will be something like this:

angular.module('betterMyClassEquals','MyClassModule').run(function(){
  var angularEquals = angular.equals;

  angular.equals = function(o1, o2) {
    if (o1 === o2) return true;
    if ((o1 instanceof MyClass) || (o2 instanceof MyClass)) {
      if ((o1 instanceof MyClass) && (o2 instanceof MyClass)) {
        return true; // here you will place the custome code for MyClass comparison
      }
      return false;
    }
    return angularEquals(o1, o2);
  };
});

[aleclofabbro]

👍
I would make it even more simple:
something like this :

function equals(o1, o2) {
    if (o1 === o2) return true;
    if (o1 === null || o2 === null) return false;
    if (o1 !== o1 && o2 !== o2) return true; // NaN === NaN
    var t1 = typeof o1, t2 = typeof o2, length, key, keySet;
    if (t1 == t2) {
      if (t1 == 'object') {
        if (o1.$equals) return o1.$equals(o2);           // if one or both objects implements
        else if (o2.$equals) return o2.$equals(o1);   // the "reserved" $equals, then use it !
...
...

[lee-elenbaas]

Setting a comparable interface works too. With less danger for framework
corruption. But it feels less javascript for me. A better approsch is an
api for adding comparators with priority. A cmparator will have 3 states
for each pair of objects: equal, not equal and not mine (can be true, false
and undefined) this structure will allow for breaking down the current
equals to smaller functions and for adding custom comparators specific for
the app. I will see if i can write it up
בתאריך 30 בינו 2014 16:16, "aleclofabbro" [email protected] כתב:

[image: 👍]
I would make it even more simple:
something like this :

function equals(o1, o2) {
if (o1 === o2) return true;
if (o1 === null || o2 === null) return false;
if (o1 !== o1 && o2 !== o2) return true; // NaN === NaN
var t1 = typeof o1, t2 = typeof o2, length, key, keySet;
if (t1 == t2) {
if (t1 == 'object') {
if (o1.$equals) return o1.$equals(o2); // if one or both objects implements
else if (o2.$equals) return o2.$equals(o1); // the "reserved" $equals, then use it !
...
...

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