#Anaphoric Case

Provides an anaphoric if, and anaphoric case-like construct as kernel methods.

###Examples:

English: If the dog is on fire, put it out!

Ruby: If the dog is on fire, put the dog out!

This is all well and good provided dog is a simple reference, but if the dog is something more complicated, you wind up either having to do an assign in the if condition, or assign to a temporary variable before you extinguish Fido.

This is similar to the use case for the andand gem. It's especially handy when the dog being on fire is not a simple binary condition. If Rin-tin-tin can summon help depending upon his dire situation, like if dog.fire also says which part of the dog is on fire, or where he is drowning at.

# Listen for sounds of distress
if dog.fire
  owner.tell(dog.fire)
elsif dog.drowning
  owner.tell(dog.drowning)
elsif dog.hungry
  owner.tell(dog.hungry)
end

An anaphoric if doesn't need to call dog.fire again in the executed block.

aif(dog.fire) { |it| owner.tell(it) }

If you have multiple conditions, you probably want to use the switch/on construct

owner.tell(switch do
  on dog.fire
  on dog.drowing
  on dog.hungry
end)

Here, the dog will tell his owner the first condition he encounters. switch can also behave like a regular case statement (albiet with fallthrough) if you like.

switch dog.name do
  on /Rover/ { |it| "Come on over #{it}"}
  on /Fido/  { |it| "Give #{it} a bone"}
  on /Rin-Tin-Tin/ { |it| "#{it} is frequently mistaken for Lassie"}
end

If the switch parameter takes a block, it will be passed into the block as an optional block parameter. In addition, the on method will yield the parameter object of the switch method, rather than it's own parameter.

If switch is called with an explicit receiver, it acts somewhat like tap in that the block is executed in the context of the receiver.