From: "Peña, Botp" <botp@...>
Date: 2007-11-15T22:27:00+09:00
Subject: Re: alias_method :tap, :affect

From: furtive
# On Nov 12, 2:31 pm, Martin
# > #tap is the opposite use case - you want to "tap" the object stream,
# > observing without affecting.
# OK I understand Object#tap now.  At first I thought the motivation was
# to modify the object inside the block, but now I see that it can be a
# useful part of functional-style ruby.
# So, to throw this out again --- there should also be Object#as which
# returns the block result (I like the name 'as' but I am not
# particularly attached to it).  I can personally attest to its
# usefulness, and I can show reams of examples in addition to the above
# one I gave.

(my previous message seems to have lost, so i apologize for a 2nd post)

tap is indispensable for me when it comes to chaining (specially bang methods)..

naive example follows...

~> s
=> "This is a test"

~> s.capitalize!.capitalize!
NoMethodError: undefined method `capitalize!' for nil:NilClass

breaks!

~> s.upcase!.upcase!
=> nil

breaks!

~> s.upcase!.capitalize!
NoMethodError: undefined method `capitalize!' for nil:NilClass

breaks!

~> s.tap(&:upcase!).tap(&:upcase!).tap(&:capitalize!).tap(&:capita
lize!).tap(&:downcase!).tap(&:downcase!)
=> "this is a test"

long chain, no break :)

btw, i like the #tap name, it's like tapping a chain so that it wont break. (i'm not an english expert but that is how i usually use the word)..

kind regards -botp