Question

consider the following code

def salt
  []
end

def pepper
  salt = salt.map{ |grain| 'ok' }
end

Gives the following result:

NoMethodError (undefined method `map' for nil:NilClass):

Why do these circumstances exactly cause an error? This is unexpected.

Answer 1

Because your local variable salt is shadowing the method salt. Since the variable salt has been just been defined, its value is nil. You can remedy this by explicitly calling salt on the instance to get the method:

def pepper
  salt = self.salt.map{ |grain| 'ok' }
end