Methods
| Define and call | |
| Arguments | |
| Defaults and kwargs | |
| Implicit return |
Define and call
The keyword def opens a method and end closes it. Method names use snake case, with words joined by underscores. Call the method by writing its name, with or without parentheses.
def greet
puts "hello"
end
greet
hello
Arguments
Names listed in parentheses become required arguments, and the call must supply the same count. Inside the body, each argument behaves like an ordinary local variable.
def add(a, b)
puts a + b
end
add(2, 3)
5
Defaults and kwargs
A default after the equals sign applies when the caller skips that argument. Keyword arguments carry names at the call site, so their order no longer matters. Use defaults for simple options and keywords when a method takes several settings.
def greet(name = "guest")
puts "hello #{name}"
end
greet
greet("Ada")
def move(x:, y:)
puts "#{x}, #{y}"
end
move(x: 1, y: 2)
hello guest
hello Ada
1, 2
Implicit return
Ruby returns the last evaluated expression, so most methods need no explicit return. The keyword return exits early with a value, which suits guard clauses. A method with nothing useful to give back returns nil.
def double(n)
n * 2
end
puts double(4)
def sign(n)
return "zero" if n == 0
"other"
end
puts sign(0)
8
zero
Next: Blocks, procs, lambdas
Article author: Arthur Isaev