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Feature #18690

open

Allow `Kernel#then` to take arguments

Added by sawa (Tsuyoshi Sawada) almost 2 years ago. Updated about 1 year ago.

Status:
Open
Assignee:
-
Target version:
-
[ruby-core:108214]

Description

Kernel#then passes the receiver to the block as its first positional block parameter.

1.5.then{|x| Math.atan(x)}

I would like to propose to let then take arguments, which would be passed to the block as the other block parameters.

3.then(4){|x, y| Math.hypot(x, y)}

There are two uses. First, to separate bulky or repeated parameters from the routine. Instead of writing:

honyarara.then{|x|
  foo(x)
  bar(fugafugafuga)
  baz(hogehogehoge)
  qux(x, fugafugafuga, hogehogehoge)
}

we can then write:

honyarara.then(fugafugafuga, hogehogehoge){|x, y, z|
  foo(x)
  bar(y)
  baz(x)
  qux(x, y, z)
}

Second, to use a proc with multiple parameters when, for some reason, you do not want to define a method to do it:

p = ->(x, y, z){
  foo(x)
  bar(y)
  baz(x)
  qux(x, y, z)
}

honyarara.then(fugafugafuga, hogehogehoge, &p)
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