On 11/11/2013 08:06 PM, Rick Johnson wrote:
Globals are justified when they are used to communicate information between scopes that otherwise were meant to be mutually exclusive.
I think this is certainly the use case most people would suggest. But I think you may have missed the real reason most modern designers object to inter-module globals: The presence of such entities almost always means the code has been designed badly. Whether we're writing pristine OO code (cough, cough) or more traditional procedural stuff, information hiding is a good thing. When and where there is a need for modules (or programs, or machines, or "clouds", or interstellar space ...) to share information, my view is this is better done via some sort of interface/message passing mechanism. The more "things" that have to be shared across modules/programs/machines/clouds/space ... the more *brittle* the end system becomes. This problem is broader than just variables, BTW. It exists anytime you share *anything* across many computational components, especially in highly parallel and/or distributed systems. For example, RPCs tend to be lousy at building high scale distributed system because they usually have a call-and-wait semantic which will fail if the caller never responds. In this case the system is sharing the semantics of *time*. As a general matter, exactly-once asynchronous messaging tends to be a better implementation model here. Just my 2 cents worth. Interesting read. Thanks for taking the time -- ---------------------------------------------------------------------------- Tim Daneliuk tun...@tundraware.com PGP Key: http://www.tundraware.com/PGP/ -- https://mail.python.org/mailman/listinfo/python-list
