What is lexical scope in Ruby?

What is lexical scope in Ruby?

Lexical scope in Ruby refers to the visibility of variables based on their location within the source code. It determines which variables are accessible in different parts of the code.

Can you give me an example of lexical scope in Ruby?

Sure! Here's a simple example:

def outer_method
  outer_var = 'I am outside'

  def inner_method
    puts outer_var  # This will raise an error!
  end

  inner_method
end

outer_method

In this case, inner_method cannot access outer_var because of lexical scoping.

What happens if I use a block?

If you use a block, the inner scope can access variables from the outer scope. For example:

def outer_method
  outer_var = 'I am outside'

  3.times do
    puts outer_var  # This will work!
  end
end

outer_method

Here, the block can access outer_var.

Are there any exceptions to this rule?

In Ruby, the main exception is when using eval or similar methods that can change the scope. However, in general, lexical scope is quite strict.