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Functions and Methods¶

Enables reusable code. DRY(Don’t Repeat Yourself)

Defining and Calling Methods¶

def hello
  puts "Hello World"
end

Calling Methods¶

hello

or alternatively with braces

hello()

Creating methods with parameters¶

def hello(name)
  puts "Hello #{name}"
end

and calling the method as follows :

hello "Joseph"
hello("Joseph")

Methods with Default Parameters¶

def hello(name="John")
  puts "Hello #{name}"
end

Constructor - Initialize Method¶

initialize is a special method in a class. Its called automatically when an object is created.

class Person
  def initialize(name)
    puts "New person created"
  end
end

When we create the new Person object, the initialize method is automatically called as demonstrated below :

irb(main):075:0> p = Person.new("Joseph")
New person created

The return statement¶

Ruby methods do not need to use the return keyword. The last expression evaluated will be returned. If a method does not return anything, it returns nil.

  def hello
    puts “Hello World” #Implicit return
  end

We can also explicitly add a return keyword as follows :

  def add(n, n1)
    return n + n1
  end

We can use it as follows :

puts add(1,2)

Returning multiple values¶

We can also return multiple values as follows :

def return_multiple
    return 10, 30.5, 50
end

and use the function as follows :

n, n1, n3 = return_multiple

Variable parameters¶

We can use the hash within the parameter list to pass in variable params. Any older way is to use the \*variable-name.

Using the hash :

def variable_params(opts = {})
    #Do something
end

older way :

def variable_params(*opts)
 puts opts.count if opts.count > 0
end

Named parameters¶

We can use symbols to name the name of the params as follows :

def full_name(first_name: "John", last_name: "Doe")
 puts "#{first_name} #{last_name}"
end

and we can now call the method as follows :

full_name(first_name: "Joseph", last_name: "Kandi")

Class methods¶

We can also have methods inside a class. We use the self keyword when defining methods on the class as follows :

class Person
  def self.count
    puts "Method on the Person class"
  end
end

and we can call the method as follows :

Person.count

Sample method signatures with required, optional, and default-valued arguments¶

Method Signatures