Mastering Ruby Closures

Block Pattern #1: Enumeration

You may have fallen in love with Ruby because of the way it does enumeration:

>> %w(look ma no for loops).each do |x|
>>   puts x
>> end
look
ma
no
for
loops
=> ["look", "ma", "no", "for", "loops"]

Besides being very expressive, enumeration using blocks is more concise and less error-prone. It is concise because the block captures exactly what we want to do with each element (printing it out to the console). It is less error-prone compared to traditional for loops because it does away with indices that are prone to the infamous off-by-one error.

You should be familiar with this way of iterating over a collection, such as an Array. What is interesting is how these methods are