Consider supporting prototype methods

[kevinoid]

Any chance you would be willing to consider supporting pify-ing the prototypally-inherited methods of passed objects?

The main issue that I'm trying to solve is that code such as:

var lovebug = pify(new Car("Herbie"));

works if the Car constructor sets/copies/binds methods to this, but not if the methods are inherited via prototype. So, unless I've missed something, pify users must either depend on the implementation of Car or roll their own method iteration wrapper for pify (and/or pify the prototype, then pify any methods set by the constructor).

If pify-ing inherited methods sounds agreeable but you'd need a PR to consider, I can work one up. I would envision the methods being copied from the prototype to the new target object if a boolean option is set, but alternatives would be fine with me.

Thanks for considering,
Kevin

[sindresorhus]

Not something I personally need, but I can see it being useful for many, so PR welcome :) Should be a boolean option that is false by default.

You might find inspiration in the Bluebird implementation https://github.com/petkaantonov/bluebird/blob/master/src/promisify.js

[kevinoid]

Great, thanks! I'll see what I can do.

[schnittstabil]

@kevinoid I assume we only consider Enumerable and Inherited Enumerable properties. In that case I think it is sufficient to choose Object.keys or for…in depending on your option at index.js#L59.

[kevinoid]

@schnittstabil I agree, that sounds like the right behavior and implementation to me. Thanks.

Feel free to do the PR if you are strongly motivated, I'm not picky about it. Otherwise I should have some time to hammer it out later today.

[schnittstabil]

Sorry @kevinoid, I do neither see the need for that option nor have much time to implement it.