JEP draft: Scope Locals

[Alan Snyder]

From the motivation section:

> So you want to invoke a method X in a library that later calls back into your code. In your callback you need some context, perhaps a transaction ID or some File instances. However, X provides no way to pass a reference through their code into your callback. What are you to do?

When I read this, my first thought was… pass a callback that is bound to the context.

I suppose the example you have in mind has a fixed callback. Is this a common practice? Doesn’t it point to a deficiency in the library API?

Is this feature just a workaround for poorly designed libraries, or are there other examples?

  Alan