Mastering Ruby Closures

Chapter 3

1. The answer is exactly the one covered in the chapter:

   class Symbol
     def to_proc
       proc { |obj, args| obj.send(self, *args) }
     end
   end

2. Since we’re interested in adding behavior to object initialization, it therefore makes sense to implement to_proc within the Class class. Here’s a possible implementation:

   class Class
     def to_proc
       proc { |args| new(*args) }
     end
   end

   Since we’re creating objects with arrays, each array element is treated as a single object. Therefore, the proc takes a single argument.

   Next, we use the splat operator to convert the array into method arguments, and pass it into new, which then calls the initializer.

3. The Proc#lambda? method.

4. Both come from the Proc class.

5. join_2. Lambdas ...