Method objects with method() in Ruby - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the method() function do in Ruby?

It returns a Method object that represents a method bound to a specific object. This allows you to store, pass, or call the method later.

beginner

How do you call a method stored in a Method object?

You use the call method on the Method object. For example, m = obj.method(:foo); m.call calls the foo method on obj.

intermediate

Can you pass a Method object as a block to another method?

Yes! You can convert a Method object to a block using the & operator. For example, array.map(&obj.method(:foo)) passes the method as a block.

intermediate

What is the difference between method() and send() in Ruby?

method() returns a Method object without calling it immediately, while send() calls the method immediately on the object.

beginner

Why might you want to use Method objects instead of calling methods directly?

Method objects let you store methods as variables, pass them around, and call them later. This helps write flexible and reusable code.

What does obj.method(:foo) return in Ruby?

A Raises an error

B Calls the method <code>foo</code> on <code>obj</code> immediately

C Returns the symbol <code>:foo</code>

D A Method object representing the method <code>foo</code> bound to <code>obj</code>

The method() function returns a Method object bound to the object, not the result of calling the method.

How do you invoke a Method object stored in variable m?

A <code>m.call</code>

B <code>m.invoke()</code>

C <code>m.execute()</code>

D <code>m.run()</code>

You call the method stored in a Method object using call.

Which operator converts a Method object to a block in Ruby?

A #

B &

C $

D *

The & operator converts a Method object to a block for passing to methods like map.

What is the main advantage of using Method objects?

A They allow storing and passing methods as objects

B They speed up method execution

C They automatically memoize results

D They replace instance variables

Method objects let you treat methods like data, storing and passing them around.

What happens if you call obj.method(:foo).call?

A Raises an error

B Returns the Method object without calling

C Calls the <code>foo</code> method on <code>obj</code>

D Returns <code>nil</code>

Calling call on the Method object invokes the method on the original object.

Explain how to create and use a Method object in Ruby.

Think about how you get a method as an object and then run it.

Describe a practical scenario where using Method objects is helpful.

Consider when you want to pass a method to another method like map or each.