its-it

This gem defines kernel methods its and it that queue and defer method calls. This is handy for list comprehension and case statements.

its and it extend the Symbol#to_proc idiom to support chaining multiple methods.

When performing a list comprehension ruby, you can use a block argument:

users.map{ |user| user.contact }

Or, to avoid needing the block and and extra parameter, you can use the Symbol#to_proc shortcut:

users.map &:contact

But if you want to chain several methods, such as:

users.map{ |user| user.contact.last_name.capitalize }

The Symbol#to_proc shortcut doesn't help much. At best, if you're willing to accept intermediate arrays, you can do:

users.map(&:contact).map(&:last_name).map(&:capitalize)

To improve the situation, this gem provides a Kernel method its, which lets you get the same shortcut advantages as Symbol#to_proc but supports chaining:

users.map &its.contact.last_name.capitalize

Also, its supports arguments and blocks, allowing you to do things like

users.map &its.contact.last_name[0,3].capitalize
users.select &its.contact.last_name.length > 10
users.select(&its.addresses.any? { |address| airline.flies_to address.city })

As a syntactic sugar, it is an alias for its, to use with methods that describe actions rather than posessives. For example:

items.map &it.to_s.capitalize

When used with hash comprehensions, the |key, val| pair of arguments are presented to its as a tuple that can be accessed array-like via [0] or [1] and/or struct-like via #key and #value methods. E.g.

{dogs: 1, cats: 2, goats:3}.select &its.key =~ /^c/ # => {cats: 2}
{dogs: 1, cats: 2, goats:3}.select &its.value.even? # => {cats: 2}
{dogs: 1, cats: 2, goats:3}.select &its[1].even? # => {cats: 2}

its and it similarly extend Ruby's case mechanism to support testing arbitrary methods, minimizing the need to create temporary variables. That is, instead of:

maxlen = arrays.map(&size).max
case
when maxlen > 10000 then "too big"
when maxlen < 10    then "too small"
else                     "okay"
end

You can use it:

case arrays.map(&size).max
when it > 1000 then "too big"
when it < 10   then "too small"
else                "okay"
end

Of course method chanining can be used here too:

case users.first
when its.name == "Gimme Cookie" then ...
when its.name.length > 10 then ...
else ...
end

The it method creates an instance of the ItsIt::It class, which uses method_missing to capture and queue up all methods and their arguments except for :to_proc and :=== (and also excepting :respond_to? :to_proc and :respond_to? :===).

:to_proc returns a proc that will evaluate the method queue on a given argument. :=== takes an argument and evaluates that proc, returning the result.

Install as usual from http://rubygems.org via

$ gem install "its-it"

or in a Gemfile

gem "its-it"

Tested on MRI ruby 2.7.1

(MRI ruby 1.9.3, 2.1.9, 2.2.5, and 2.3.1 were supported up through version 1.3.0)

(MRI ruby 1.8.7 was supported up through version 1.1.1)

Release Notes

• 2.0.0 Switch to Ruby 2.7 keyword syntax. No other breaking changes.
• 1.3.0 Add #key and #value for Hash comprehensions; plus minor internal cleanup.
• 1.2.1 Don't leak all of ItsIt into main, just ItsIt::Kernel. Thanks to klg
• 1.2.0 Add support for Hash comprehensions; drop support for ruby 1.8.7
• 1.1.1 Remove dependency on BlankSlate

This gem is orignally based on Jay Philips' methodphitamine gem. It has been made available on rubygems.org, and updated over the years.