Added :args to Future and Promise options hash.

[jdantonio]

This PR addresses the enhancement discussed in #223. It adds an :args option to the constructor and factory of Future and Promise. The value of this option, when set, can be either a single value or an array of zero or more values. When the args option is given the values will be passed to the underlying executor and, subsequently, passed to the task block. Providing :args isolates the scope of the variables so that they can be re-assigned within the closing scope. The passed variables are still mutable object references that can be modified within the task block.

[coveralls]

Coverage increased (+0.01%) when pulling ad10456 on refactor/future-args into 1241953 on master.

[jdantonio]

The following examples now work as expected:

require 'concurrent'

value = 100
future = Concurrent::Future.execute(args: value) do |t_value|
  sleep 1
  t_value + 1
end
value = 200
p future.value #=> 101


value = (1..10).to_a
future = Concurrent::Future.execute(args: value) do |*t_value|
  sleep 1
  t_value << 1000
end
value = nil
p future.value #=> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 1000]

[coveralls]

Coverage increased (+0.09%) when pulling 6bd5b08 on refactor/future-args into 1241953 on master.

[jrochkind]

makes sense to me!

[pitr-ch]

nitpick: lost space

[jdantonio]

Fixed! :-)

[pitr-ch]

LGTM

[coveralls]

Coverage increased (+0.01%) when pulling a9dd938 on refactor/future-args into 1241953 on master.

[coveralls]

Coverage increased (+7.18%) to 91.77% when pulling e3e0501 on refactor/future-args into 474bdf6 on master.