Question:
In ruby, it is possible to make a call to any method, either on an object, either using :: or using . . What is the difference between them?
Answer:
Not just any method can call like that. You use this operator to indicate that you are using a namespace , a module or class name, until you reach a member, but since you are accessing a module or class member, you can only access members that are part of the type but not the object , so static methods can be accessed, but not instance. It can also be used for fields and constants, as long as they belong to the type or module.
Example:
x = 0
module Teste
x = 0
::x = 1
end
puts x #gobal, vale 1
puts Teste::x #do módulo vale 0
I put it on GitHub for future reference .
Note that if you use the operator without a name the language assumes it is the global name.
It's just the form used for name resolution with a specific qualifier. So don't confuse with . which is used for solving a member of an object.