Ruby dot and double colon operators
Ruby . and :: operators
In Ruby you call a module method by preceding its name with the module's name and a period and you refer a constant using the module name and two colons.
The :: is a unary operator and is used to access (anywhere outside the class or module) constants, instance methods and class methods defined within a class or module.
Note: In Ruby, classes and methods may be considered constants too.
You must prefix the :: Const_name with an expression that returns the appropriate class or module object. If no prefix expression is used, the main Object class is used by default.
Here is an example :
X = 0 # constant defined on main Object class module Calculate X = 0 ::X = 10 # set global count to 10 X = 20 # set local count to 20 end puts X # this is the global constant puts Calculate::X # this is the local "Calculate" constant
abc.rb:4: warning: already initialized constant X abc.rb:1: warning: previous definition of X was here abc.rb:5: warning: already initialized constant Calculate::X abc.rb:3: warning: previous definition of X was here 10 20
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