What are some common use cases for closures in Ruby?

What are some common use cases for closures in Ruby?

Closures in Ruby are often used for callbacks, encapsulating state, and creating domain-specific languages. They allow you to define a block of code that can be executed later, maintaining access to the variables in its scope.

Can you give me an example of a closure in Ruby?

Sure! Here's a simple example:

add = ->(x, y) { x + y }
result = add.call(2, 3)
puts result  # Outputs: 5

This lambda is a closure that adds two numbers.

How do closures help with encapsulating state?

Closures can capture and remember the environment in which they were created. For instance, you can create a counter that maintains its state across multiple calls:

def make_counter
  count = 0
  -> { count += 1 }
end

counter = make_counter()
puts counter.call()  # Outputs: 1
puts counter.call()  # Outputs: 2

Are there any performance considerations when using closures?

Yes, closures can introduce overhead due to the additional scope they create. However, in most cases, the benefits of using closures for cleaner and more maintainable code outweigh the performance costs.