Ruby in a Nutshell

Name

def Statement for Singleton Methods

Synopsis

def
receiver.method([arg...,arg=default..., *arg, &arg])
code
[rescue [exception_class[, exception_class...]] [=> variable] [then]
	code]...
[else
	code]
[ensure 
	code]
end

Tip

A period . after receiver can be replaced by two colons (::). They work the same way, but :: is often used for class methods.

A restriction in the implementation of Ruby prevents the definition of singleton methods associated with instances of the Fixnum or Symbol class.

a = "foo"
def a.foo
  printf "%s(%d)\n", self, self.size
end
a.foo     # "foo" is available for a only