just-partial-it implementation questions about just HOT 4 CLOSED

Craig stole my thunder. Get out of here Craig! (We work together...=D).

from just.

Actually this is a great question.
When you invoke partial you need to pass placeholder arguments for this arguments you want to supply at runtime. In the following example we want to return a function that resolves the cubed root of something. That something is the placeholder indicated by _

import partial from 'just-partial-it';

const cubedRoot = partial(Math.pow, _, 1/3);
cubedRoot(10).toFixed(1); // 56.7
cubedRoot(35).toFixed(1); // 16.2

We need a way for the caller of partial to pass in an argument that will be recognized as a placeholder. One way to do this is to use a global variable. This is where globalObj.___ comes in.

Your question reveals a shortcoming in my example. We should first assign _ to globalObj.___ before calling partial. (without this the function would likely throw an error since _ is probably undefined).

So for the example to work properly we need:

import partial from 'just-partial-it';

var _ = global.___;
const cubedRoot = partial(Math.pow, _, 1/3);
cubedRoot(10).toFixed(1); // 56.7
cubedRoot(35).toFixed(1); // 16.2

Which is annoying. I'm going to rewrite this to just use null as the placeholder which will mean we can remove all this global nonsense.

Thanks for bringing to my attention!

from just.

Actually using _ (which is undefined) results in NaN as result from examples. Pull request #8 uses undefined as placeholder. null could be valid and useful value to pass, but undefined is clear, explict, and unambigous (i.e. null is value or placeholder?)

from just.

@camerow feel free to find another bug :)

from just.