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Subject: Re: Design thought for callbacks
From: Cem Karan <cfkaran2@gmail.com>
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Date: Mon, 23 Feb 2015 06:47:10 -0500
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On Feb 22, 2015, at 5:29 PM, Laura Creighton <lac@openend.se> wrote:

> In a message of Sun, 22 Feb 2015 17:09:01 -0500, Cem Karan writes:
>=20
>> Documentation is a given; it MUST be there.  That said, documenting
>> something, but still making it surprising, is a bad idea.  For
>> example, several people have been strongly against using a WeakSet to
>> hold callbacks because they expect a library to hold onto callbacks.
>> If I chose not to do that, and used a WeakSet, then even if I
>> documented it, it would still end up surprising people (and from the
>> sound of it, more people would be surprised than not).
>=20
>> Thanks, Cem Karan
>=20
> No matter what you do, alas, will surprise the hell out of people
> because callbacks do not behave as people expect.  Among people who
> have used callbacks, what you are polling is 'what are people
> familiar with', and it seems for the people around here, now,
> WeakSets are not what they are familiar with.

And that's fine.  I know that regardless of what I do, some people are =
going to be surprised.  I'm trying to develop APIs that reduce that =
surprise as far as possible.  That means I can spend more time coding =
and less time answering questions... :)

> But that is not so surprising.  How many people use WeakSets for
> _anything_?  I've never used them, aside from 'ooh! cool shiny
> new language feature!  Let's kick it around the park!'  That people
> aren't familiar with WeakSets doesn't mean all that much.

Actually, I use them when building caches of stuff, and I use weak =
references when I have trees of stuff so the child nodes know of, but =
don't hold onto, their parents.  But I agree with you, there aren't a =
huge number of use-cases.

> The question I have is does this architecture make things harder,
> easier or about the same to debug?  To write tests for? to do Test
> Driven Design with?

Good questions!  That was why I was asking about 'gotchas' with WeakSets =
originally.  Honestly, the only way to know for sure would be to write =
two APIs for doing similar things, and then see how people react to =
them.  The problem is, how do you set up such a study so it is =
statistically valid?

Cem=