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Hi Neil, hope you are having a nice day

13 Nov 04, Neil Heller wrote to Serge Baltic:

 SB>> What do the constructors do to running multiple instances of your
 SB>> application?
 NH> If a constructor is private, it cannot be constructed by any process
 NH> other than itself.

What the hell about other processes? If a constructor is private, the
object cannot be created directly by either process. What is a "self
process"? Each process is self for some classes :)

It can be created in some function of this class. A static one, for obvious reasons.

 NH> In the public GetInstance() method,

"static" in the first place.

 NH> the reference can get checked for zero (having been declared static,
 NH> it will be initialized to zero when created) and if zero, the class
 NH> is created on the heap.

This does not prevent me from creating two instances of this object in
different processes. Moreover, I can even create two instances in a single
process if I load them from different modules --- because each module will
have a personal set of static variables and your singleton model will be
local to the module.

A static var is not enough. It would rather be some system synchronization
object, like a semaphore (within the process) or a mutex (interprocess as
well). Under Win* COM the model could be used to handle the singleton
problem.


 -=> Yours sincerely, Serge <=-

BTW, The world's oldest piece of chewing gum is over 9000 years old.

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