SelfieChain

NOTE: It was my first gem, but now I know that there are much better alternatives. You can just use any sort of Maybe-like gem; and for hash it's even better to use Hash#dig starting from Ruby 2.3 (or implement it yourself:

Hash.class_eval do
	def dig(*keys)
 		return self if keys.empty?

 		ret = self[keys.shift]

 		ret.nil? || keys.empty? ? ret : ret.dig(*keys)
 	end
end unless {}.respond_to?(:dig) # already implemented in Ruby 2.3

)

Now every object can take a selfie. SelfieChain is an attempt to complement ruby's ternary operator, null guard and somehow extend Rails' :try method (but you don't need Rails), all in one-shot. I realised that there are use cases, that the above mentioned tools fail to address in sufficently elegant way. Look below for some explanatory examples and start taking selfies :)

Installation

Add this line to your application's Gemfile:

gem 'selfie_chain'

And then execute:

$ bundle

Or install it yourself as:

$ gem install selfie_chain

Usage

SelfieChain adds a :selfie method to Object class (as well as a SelfieChain:Wrapper < BasicObject class). Calling it with or without a block changes it's behavior as follows:

####1. With block (and one optional argument that defaults to nil).

Passes the receiver to the block. If the block returns true, then the whole method returns the receiver; otherwise it returns the argument:

	h = {a: {b: {}}} (hashes make nice examples)
	
	h[:a][:b][:c].to_i.selfie(-1) {|x| x > 0} => -1 
	
	h[:a][:b] = {c: "14"}
	h[:a][:b][:c].to_i.selfie(-1) {|x| x > 0} => 14

You don't have to repeat the long method call chain, selfie let's you replace this expression with mere 'x' inside the block (that's where the name comes from: "self-if", transmutes into "selfie" quite easily)

####2. Without block (no arguments needed).

This let's you stop worrying about checking for possible nil every time you chain another method*:

	h.selfie[:a][:b][:c]["d"].to_i.share_selfie => nil

	h[:a][:b][:c] = {"d" => "14"}
	h.selfie[:a][:b][:c]["d"].to_i.share_selfie => 14

This time selfie returns SelfieChain.new(self) - instance of SelfieChain < BasicObject class that wraps the receiver. This wrapper delegates every method call (except for :share_selfie and those defined by BasicObject) to the wrapped object - and swaps it with the result unless the wrapped object doesn't respond_to? the method, in which case the wrapper stores nil. NOTE, that once the wrapped object hits nil, it always stays nil (this conforms to the Rails' :try method mechanics). You can end this method calling chain party and retrieve the result by calling :share_selfie.

####3. Share_selfie with block (from v.1.1.0)

Now you can pass a block to share selfie:

	h[:a][:b][:c] = {"d" => "14"}
	h.selfie[:a][:b][:c]["d"].to_i.share_selfie(-1) {|x| false} => -1

It works just like (...).share_selfie.selfie(-1) {|x| false} with the only exception, that when share_selfie is to yield nil, it still yields nil no matter what the given block would evaluate to (it's not called at all):

	h[:a][:b] = {c: "14"}
	h.selfie[:a][:b][:c]["d"].to_i.share_selfie(-1) {|x| false} => nil
	h.selfie[:a][:b][:c]["d"].to_i.share_selfie.selfie(-1) {|x| false} => -1

---

• Here we use string "d" instead of symbol :d to avoid known "no implicit conversion of Symbol into Integer" exception raised by calling "14"[:d].

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake test to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/swarzkopf314/selfie_chain.

License

The gem is available as open source under the terms of the MIT License.