Block are one of the most important and most used features of Ruby. They are very similar to anonymous functions in other languages.

They are very common - here is an example:

[1, 2, 3].each do |n|
  puts "#{n}"

Just like with methods - they take arguments, performdefined tasks and return a value. In fact, their syntax is very similar to the to the method syntax:

do |arguments|

Curly braces can be used instead of the do-end syntax:

{ |arguments|

NB: These 2 ways of definining a block are identical.

Returning value

Just like with methods, a block returns the value of the last statement inside the block.

You get a block, and you get a block

... everyone gets a block!

Every method in Ruby has a hidden block parameter that the method can yield to:

def say_hello_to(name)
  puts "Hello #{name}"
  yield name
say_hello_to("Jenny") { |n| puts "#{n} from the block" }
    Hello Jenny
    Jenny from the block