Ability to reflect on prop-type instances?

[sullvn]

Hello!

I'm looking for a way to reflect on generated prop-type instances. The purpose is for use in developer tooling.

The problem is that the generated instances are opaque functions with any meaningful metadata hidden in closures. I could maybe see this by design to discourage monkey-patching, but it's closing the door on some cool possibilities.

Example: https://runkit.com/awfulaxolotl/lack-of-reflection-in-prop-types
A use case: sullvn/tastes#6

So I guess my question comes down to:

1. Could this be an addition?
2. If I made a PR, would it be accepted?

Thanks!

[wjljack]

i need too,use in storybook knobs,reflect prop-types can auto generate knobs easily.

[cpimhoff]

Given a proptype value specified on an object, you can find the key it comes from via a brute force search. This only works for the basic prop types (ie. not things like arrayOf), and not in production, since all the functions of the prop-type package is shimmed out when the nodeEnv is production.

import PropTypes from 'prop-types';
import findKey from 'lodash/findKey';

MyButton.propTypes = {
    disabled: PropTypes.bool
    onClick: PropTypes.func.isRequired
};

function getPropTypeName(typeEntry) {
    return findKey(PropTypes, p => p === typeEntry || p.isRequired === typeEntry);
}

getPropTypeName(MyButton.propTypes.disabled);  // 'bool'
getPropTypeName(MyButton.propTypes.onClick);  // 'func'

[ljharb]

https://npmjs.com/find-value-locations can help with that

[sullvn]

@cpimhoff @ljharb Thanks for the help on a partial solution. Looking up prop types by reference is certainly better than nothing 😸

However, full reflection is unfortunately required for my usecases. This includes reflecting on nested prop types and other prop types with custom constructor arguments.

[ljharb]

Duplicate of #60.