Params Ruby

Different types of parameter in Ruby:#

1. Positional Params#

def sum(salary, bonus, tax)
salary + bonus - tax
end
sum(100, 10, 30) # => 80

2. Keyword Param#

  • Introduced at Ruby 2.0.
  • Keyword arguments allow us to switch the order of the arguments, without affecting the behavior of the method.
  • Also known as named parameters, keyword arguments, required keyword arguments.
def sum(salary:, bonus:, tax:)
salary + bonus - tax
end
sum(salary: 100, bonus: 10, tax: 30) # => 80

Passing default value:#

def sum(salary:, bonus: 10, tax:)
salary + bonus - tax
end
sum(salary: 100, tax: 30) # => 80

3. Variable Arguments:#

def print_all(**args)
print args
end
print_all(1, 2, 3) # =>

The **x is the same as variable arguments, but for keyword arguments. It will be a hash instead of an array.

4. Catch-all Argument:#

def print_all(*)
end

This means that the method is accepting any arguments, but it’s not doing anything with them. It’s similar to using the underscore character (_) inside a block to show which arguments you aren’t using.

Order#

required -> optional -> variable -> keyword
def testing(a, b = 1, *c, d: 1, **x)
p a,b,c,d,x
end
testing('a', 'b', 'c', 'd', 'e', d: 2, x: 1)

Benefits of Keyword params:#

  • Order doesn't matter
  • If order chagges on the method parameter, argument doesn't have to change on all the places where it's called.
  • Usually, the code clarity and maintainability gained from keyword arguments outweigh the terseness offered by positional arguments.

Parameter vs Arguments:#

Argument:

  • The entity that we can pass to the method during the call is called an argument.

Parameter:

  • The entity that we declare when we define a method is called a parameter.

When we pass arguments to a method, the method creates a local variable which has the same name

In ruby, arguments inside a method are passed by reference

Interesting Facts:#

1. Parentheses for paramters are optional:#

def method_name a,b,c
puts a,b,c,d
end
method_name 0,1,2

But it's recommended for redeability.

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