docs(data-point/README.md): State in README that constants should not contain other reducers

[abepeterkin]

closes #201

[coveralls]

Coverage remained the same at 100.0% when pulling 7c2450f on abepeterkin:docs/prevent-reducers-inside-of-constants into a636938 on ViacomInc:master.

[raingerber]

Just fyi you should preface the "#201" with a keyword like "fix" or "closes":

https://help.github.com/articles/closing-issues-using-keywords/

[paulmolluzzo]

LGTM!

[acatl]

can we change the wording a bit, i believe its not that yoy should not pass a reducer, but that which ever value you pass will be evaluated only as a constant/static value ? @raingerber @paulmolluzzo ?

[paulmolluzzo]

@acatl I see your point, sure. 🤔 Maybe it's good to keep this small line and add what you wrote too? Something like:

The constant reducer always returns the given value, and any value passed to constant will be evaluated only as a constant/static value. Constants that contain other reducers will not be evaluated, but will be returned as a function.

I'm not sure of the wording of the last sentence, tbh. It also feels like we're repeating the same thing a few times. (e.g. "Constants are constant and return a static/constant value...") 😅

• Edited like 25x to get the formatting right. 🙈

[raingerber]

I can't think of a better way to explain this in words, but having an example to go with the current text might help. Here's a quick example that (hopefully) could be shortened:

const DataPoint = require('data-point')

const { constant } = DataPoint.helpers

const dataPoint = DataPoint.create()

const input = {
  b: 1
}

// ReducerObject that contains a ReducerPath ('$a')
let reducer = {
  a: '$b'
}

dataPoint.resolve(reducer, input) // => { a: 1 }

// both the object and the path will be treated as
// constants instead of being used to create reducers
reducer = constant({
  a: '$b'
})

dataPoint.resolve(reducer, input) // => { a: '$b' }

[acatl]

closing this PR since it hasn't been active, please re-open it once you have it ready

[abepeterkin]

Instead of changing the description of constants to say you shouldn't put reducers inside of constants, I added the example @raingerber made in order to show what happens when you do.

[raingerber]

we should still keep the "Constants should not contain other reducers." sentence that you originally added

[abepeterkin]

Good idea

[acatl]

I rather have it taken off or changed since the actual content of a constant could be later on used to build a reducer. The only fact is that constant will not evaluate their content, they can contain any type of value. So this comment is misleading.

[acatl]

if we pass a reducer function as a constant, on a second iteration another reducer could use this value to execute itself

'model:foo': {
   value: [
      { a: c((val) => val * 2) },
      (val) => val.a(2)
   ]
}

This only applies to Function Reducers, what I'm trying to articulate is just that constants can have anything, even a reducer if they want, just nothing will be evaluated, everything is taken as-is

[raingerber]

this summary is a little misleading, since these constants are still "evaluated". not sure how to reword it though; maybe something like this?

reducers are not evaluated when they're defined inside of constants

[paulmolluzzo]

More specifically, no functions inside of a constant are evaluated, right?

[raingerber]

That's true, but this particular example doesn't have a function inside of a constant. If we do add that to the example (which wouldn't hurt), we still want to get across the fact that any reducer type inside a constant is not evaluated

[paulmolluzzo]

Cool, thanks for confirming.

[acatl]

Please remove the section 'Constants should not contain other reducers.' everything else looks good to me.

[acatl]

I rather have it taken off or changed since the actual content of a constant could be later on used to build a reducer. The only fact is that constant will not evaluate their content, they can contain any type of value. So this comment is misleading.

[raingerber]

the actual content of a constant could be later on used to build a reducer

It doesn't really make sense to do that, and I don't think it's actually possible.

[paulmolluzzo]

Still looks good to me. As long as everyone’s OK with the phrasing.

[paulmolluzzo]

Extra lines?