Contents
Outline
The Method(Function) is used to define the process in the program, and call when necessary. In this blog post, we will see how to use the Method in Ruby.
Define
You can define the Method like below.
def add(a, b)
x = a + b
return x
end
puts add(1, 2)
# 3
Return
You can omit the last return of the Method.
def add(a, b)
x = a + b
end
puts add(1, 2)
# 3
If the last return is omitted, the last variable is returned automatically.
Bracket
You can omit the bracket if the parameter does not exist.
def print
puts 'Hello'
end
print
# Hello
Parameter
Parameter’s default
You can set the Parameter’s default like below.
def add(a, b = 2)
x = a + b
end
puts add(1)
# 3
Block parameter
You can send the Block(process group) to the Method via the parameter with & character like below.
def temp(&a)
a.call
end
temp {
puts "Hello"
puts "World"
}
# Hello
# World
To execute the block, you should use the call method.
def temp(&a)
a.call
end
temp do
puts 'Hello'
puts 'World'
end
# Hello
# World
Variable length parameter
You can use the variable-length parameter with * character like below.
def temp(num, *n)
puts num
puts n
end
temp(1, 2, 3)
puts '------------'
temp(1, 2, 3, 4, 5)
# 1
# 2
# 3
# ------------
# 1
# 2
# 3
# 4
# 5
undef and defined
undef
You can cancel the defined Method by undef.
def temp
puts 'Hello'
end
temp
undef temp
temp
# Hello
# Traceback (most recent call last):
# temp.rb:9:in `<main>': undefined local variable or method `temp' for main:Object (NameError)
defined
You can check the Method exists or not by defined.
def temp
puts 'Hello'
end
puts defined? temp
undef temp
puts defined? temp
# method
#
When you use defined, you can see the string indicating the kind of expression defined like below.
# super
# method
# yield
# self
# nil
# true
# false
# assignment
# local-variable
# local-variable(in-block)
# global-bariable
# instance-variable
# constant
# class variable
# $&
# $`
# $1
# $2
# expression
Completed
We’ve seen how to define and use the Method in Ruby. Also, we’ve seen Ruby’s unique feature. Let’s define the Method and use it in Ruby!
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