Feature #19118: Allow numbered arguments to be inherited by block

• Status: Closed
• Assignee: -
• Target version: -

[0x1eef (0x 1eef)]

Each these examples does not work as I would have hoped - each of them evaluates to puts(nil).

def foo
  yield
end
[1,2,3].each do
  Process.wait fork { puts(_1) }
end
[1,2,3].each do
  Thread.new { puts(_1) }.join
end
[1,2,3].each do
  foo { puts(_1) }
end

Is it possible for numbered parameters to be inherited if the inner block is yielded with no arguments ?

Thanks!

[matz (Yukihiro Matsumoto)]

• Status changed from Open to Closed

I am sorry, but I don't think it's possible. fork or Thread.new may pass some values to the block that should be referenced by its own numbered parameters.

We have no way to distinguish whether it's possible to inherit outer ones or not.

Matz.

[0x1eef (0x 1eef)]

Alright - no worries. Thank you!

[austin (Austin Ziegler)]

matz (Yukihiro Matsumoto) wrote in #note-1:

I am sorry, but I don't think it's possible. fork or Thread.new may pass some values to the block that should be referenced by its own numbered parameters.

We have no way to distinguish whether it's possible to inherit outer ones or not.

This is entirely tongue-in-cheek, but we could count the number of underscores…

[1,2,3].each do
  foo { puts(__1) }
end

And if the it proposal is ever accepted, we could count the number of is:

[1, 2, 3].each do
  foo { puts iit }
end