Re: Coroutine __close metamethod proposal

[Roberto Ierusalimschy <roberto@...>]

>  Philipp> And maybe functions should have a default toclose behavior as
>  Philipp> well.
> 
> The ability to use a function as a toclose value previously existed, but
> was removed - I guess (from the timing) as a result of a discussion I
> had on the list about how a restricted environment needs control over
> what happens in error handling.
> 
> As it stands, if an environment doesn't expose setmetatable() to the lua
> code, then it can ensure that the lua code can't get control over error
> handling other than with pcall, which the environment can intercept.

Right. And there is one more reason:

    * Functions interact badly with coroutines. If a coroutine yields
    and is never resumed again, its to-be-closed functions will never
    run. To-be-closed objects, on the other hand, will still be closed,
    provided they have appropriate finalizers.
    
-- Roberto