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Contents
# TITLE:
#
# K-Combinators, Tap and Returning
#
# SUMMARY:
#
# Veriations on K-Combinator, namely #tap and
# #returning, and returning's alias #with.
#
# AUTHORS:
#
# - Mikael Brockman
# -Thomas Sawyer
#
module Kernel
# Yield self and return self.
def tap &b
if b.arity == 1
yield self
else
instance_eval(&b)
end
self
end
# A Ruby-ized realization of the K combinator.
#
# returning Book.new do |book|
# book.title = "Imperium"
# book.author = "Ulick Varange"
# end
#
# Also aliased as #with.
#
# def foo
# with values = [] do
# values << 'bar'
# values << 'baz'
# end
# end
#
# foo # => ['bar', 'baz']
#
# Technically, #returning probably should force the return of
# the stated object irregardless of any return statements that
# might appear within it's block. This might differentiate
# #returning from #with, however it also would require
# implementation in Ruby itself.
def returning(obj=self)
yield obj
obj
end
alias :with :returning
# Repeat loop until it yeilds false or nil.
def complete
loop { break unless yield }
end
end
# _____ _
# |_ _|__ ___| |_
# | |/ _ \/ __| __|
# | | __/\__ \ |_
# |_|\___||___/\__|
#
=begin test
require 'test/unit'
class TCKernel < Test::Unit::TestCase
def test_returning
foo = returning( values = [] ) do
values << 'bar'
values << 'baz'
end
assert_equal( ['bar', 'baz'], foo )
end
def test_tap
x = "foo"
r = ("foobar".tap{ gsub! /bar/, '' })
assert_equal(x, r)
end
def test_tap_array
x = [1,2,3]
x.tap{ |a|
assert_equal(x, a)
}
end
end
=end
Version data entries
7 entries across 7 versions & 1 rubygems