Computed properties inferring dependents attributes

[samuelsimoes]

I was thinking that computed properties could have some sort of magic that dependent attributes would be read from the computer function's text body.

Example: you have a computed property about if you can add a ToDo, the canAddTodos property, that depends on this.data.todosCount, like this:

class Todo extends Fluxo.ObjectStore {
  static computed = { canAddTodos: [] };

  canAddTodos () {
    return this.data.todosCount <= 10;
  }
}

Reading the method body string we could infer that this computed property relies upon the todosCount store property, so we can cut the necessity to user declares the change:todosCount event to compute the value, speeding up the things.

What do you think?

[samuelsimoes]

The main idea: https://github.com/fluxo-js/fluxo/commit/0a2dbb54c5a4d4af96c8fbd4671ab6829a1eadd7

[samuelsimoes]

We can extend this behavior to subsets too.

And we can also infer the add and remove events automatically when we find this.where on some computer function. My main concern with this will be the nested stores feature, nested stores won't be caught by the patterns described above.

[sobrinho]

I really prefer to be explicit because this can break in all sort of things, i.e.:

canAddTodos () {
  const data = this.data;

  // alias
  return data.foo && data.bar;
}

canAddTodos () {
  // different context (i.e.: this on the function is about the SomeService)
  return SomeService.call(function () { return this.data.foo });
}

Although we can improve the current API to something like:

fullName (firstName, lastName) {
  return `${firstName} ${lastName}`;
}

In that case the dependent attributes would be explicit at the method definition.

[samuelsimoes]

On the second example, I need to declare change:firstName and change:lastName events? Or Fluxo will read the arguments and infer the dependent events?

[sobrinho]

They would be inferred.

Since these compute functions does never receive any argument, we could use the argument names to infer what is needed to the compute.

[samuelsimoes]

Great. I liked. :ok_hand: Can I Implement this?

[sobrinho]

"Go get 'em, Tiger."

[samuelsimoes]

Do you know some safe way to get the function arguments? Thus far I only know the regexp /\([\w|\s|,]+\)/ on the function's string, but it's fragile. :pensive:

var foo = function (bar) {};
foo.arguments; // => undefined

[sobrinho]

Apparently there is no native reflection for functions, only regexps: http://stackoverflow.com/questions/1007981/how-to-get-function-parameter-names-values-dynamically-from-javascript

We could make some kind of transpiler (babel transpiler) but it doesn't worth at all.

Honestly, I don't think it's worth the complexity, too little benefit to too much complexity, explicit is always better than implicit (zen of python).

[samuelsimoes]

Alright, I also agree that It doesn't worth the complexity. Closing...