Method objects with method() in Ruby - Step-by-Step Execution

Concept Flow - Method objects with method()

Define a method

↓

Call method() on object

↓

Get Method object

↓

Call .call on Method object

↓

Execute original method

↓

Return result

This flow shows how calling method() on an object returns a Method object, which can be called later to run the original method.

Execution Sample

Ruby

class Greeter
  def hello
    "Hello!"
  end
end

g = Greeter.new
m = g.method(:hello)
puts m.call

This code creates a Method object for the 'hello' method and calls it to print 'Hello!'.

Execution Table

Step	Action	Object State	Method Object	Output
1	Create Greeter instance g	g = #<Greeter:0x000...>	nil	nil
2	Call g.method(:hello)	g unchanged	Method object for hello bound to g	nil
3	Call m.call	g unchanged	Method object still exists	"Hello!" printed
4	End of program	No change	No change	Program ends

💡 Program ends after printing 'Hello!' from the Method object call

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	Final
g	nil	#<Greeter:0x000...>	#<Greeter:0x000...>	#<Greeter:0x000...>	#<Greeter:0x000...>
m	nil	nil	Method(:hello) bound to g	Method(:hello) bound to g	Method(:hello) bound to g

Key Moments - 3 Insights

Why do we need to call .call on the Method object?

The method() call returns a Method object, which is like a saved reference to the method. To actually run the method, we must call .call on that Method object, as shown in step 3 of the execution_table.

Does calling method() execute the method immediately?

No, calling method() only returns a Method object without running the method. The method runs only when .call is used on that Method object, as seen between steps 2 and 3.

Is the original object changed after getting the Method object?

No, the original object remains unchanged throughout. The Method object just holds a reference to the method bound to that object, as shown in the Object State column.

Visual Quiz - 3 Questions

Look at the execution_table at step 2. What does g.method(:hello) return?

A nil

B The string 'Hello!'

C A Method object bound to g

D An error

💡 Hint

Check the 'Method Object' column at step 2 in the execution_table.

At which step is the original 'hello' method actually executed?

A Step 1

B Step 3

C Step 2

D Step 4

💡 Hint

Look for when the output 'Hello!' is printed in the execution_table.

If we skip calling m.call, what will be the output?

A nil

B Method object printed

C Hello!

D Error

💡 Hint

Refer to the Output column in the execution_table for step 2 and 3.

Concept Snapshot

Use method(:name) on an object to get a Method object.
Call .call on that Method object to run the original method.
method() does NOT run the method immediately.
The Method object keeps the method bound to the original object.
Useful to store or pass methods as objects.

Full Transcript

This visual trace shows how Ruby's method() works. First, an object is created from a class with a method. Calling method(:method_name) on the object returns a Method object, which is a reference to that method bound to the object. This does not run the method yet. To run it, you call .call on the Method object. The output appears only after .call is used. The original object remains unchanged throughout. This lets you save methods as objects and call them later.