From: "trans (Thomas Sawyer)" <transfire@...>
Date: 2012-12-24T04:15:23+09:00
Subject: [ruby-core:51100] [ruby-trunk - Feature #7612] Enumerators take a proc


Issue #7612 has been updated by trans (Thomas Sawyer).


=begin
Use `&`:

  e.each(&p1)
  e.each(&m2)
  e.each(&p2)
=end

----------------------------------------
Feature #7612: Enumerators take a proc
https://bugs.ruby-lang.org/issues/7612#change-35034

Author: pedz (Perry Smith)
Status: Open
Priority: Normal
Assignee: 
Category: 
Target version: 


If there is already a clean syntax for this, I apologize.  I sure could not find it.

class Foo
  def initialize
    @inst = 18
  end

  def meth(a, b)
    puts "method #{@inst} #{a} #{b}"
  end
end

foo = Foo.new

e = %w{a b c}.each_with_index
p1 = Proc.new { |a, b| puts "proc #{a} #{b}" }
m2 = foo.method(:meth)
p2 = m2.to_proc

# Current Syntax possibilities
e.each { |a, b| puts "direct #{a} #{b}" }
e.each { |a, b| foo.meth(a, b) }
e.each { |a, b| p1.call(a,b) }
e.each { |a, b| m2.call(a,b) }
e.each { |a, b| p2.call(a,b) }

# Proposed Addition

e.each(p1) # same as e.each { |a, b| p1.call(a,b) }
e.each(m2) # same as e.each { |a, b| m2.call(a,b) }
e.each(p2) # same as e.each { |a, b| p2.call(a,b) }

# In the case of a method or lambda, the arguments are checked and possible errors thrown.
# In the case of a proc, the proc "tricks" apply

To add readability, an "apply_to" method could be added:

e.apply_to(p1)

The extra "each" bothers me since the enumerator already has an "each" associated with it.



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