[RUBY] Find out about class methods

Yesterday I looked up instance methods This time we will look at class methods

Define a class method

There are two ways to define

class class name
  def self.Class method name

If you have a lot of class methods you want to define You don't have to add self every time, so it's convenient because the amount of code to write is reduced!

class class name
  class << self
def class method name

Actually move


class Calculation
  def addition(a, b, c, d, e)
    puts a + b + c + d + e

addition(1,2,3,4,5) #=> undefined method~

Then, NoMethodError occurs


class Calculation
  def self.addition(a, b, c, d, e)
    puts a + b + c + d + e

Calculation.addition(1,2,3,4,5) #=> 15


-What is a class method? The receiver is a class name and the method for that class name -Useful when creating methods to change or refer to information related to the entire class -When defining, " def self. Class method name "

Reference article

Cherry book https://qiita.com/right1121/items/c74d350bab32113d4f3d https://qiita.com/right1121/items/c3997653a621c74fb97d

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