Programming Crystal

Chaining Methods

I know you like beautiful code—otherwise you wouldn’t be reading this book. Data conversion often requires a predictable sequence of methods. One of the nice things about Crystal is that you can chain methods to create more readable code. A method can be called on any object on which it’s defined, and that object can be the result of another method call. Take a look at the following examples:

types_and_control_flow/chaining.cr

result = (42..47).to_a                          # => [42, 43, 44, 45, 46, 47]
           .sort { |n, m| m <=> n }             # => [47, 46, 45, 44, 43, 42]
           .reject { |n| n.odd? }               # => [46, 44, 42]
           .map { |n| n * n }                   # => [2116, 1936, 1764]
           .select { |n| n % 4 == 0 }           # => [2116, 1936, 1764]
           .tap { |arr| puts ...