CODEWITHSUNDEEP
c++design-patternsembedded
balgajo
balgajo

Reputation: 9

Best way to ensure single instance but not global in C++

I am developing a class to control a network adapter and I need to ensure that there's only a single instance of this class. Global access isn't necessary as this class is only used by clients that perform network operations, so I think that's not the case for the singleton pattern.

Currently I have a factory which has a static instance of this netAdapter but I'm not sure that's a good solution.

What's the best way to do this and avoid testability problems?

EDIT: I have more than one adapter(wifi, ethernet, 2G/3G/4G), but I can only have a single instance of each.

Upvotes: 0

Views: 392

Answers (1)

eerorika
eerorika

Reputation: 238401

I need to ensure that there's only a single instance of this class.

... so I think that's not the case for the singleton pattern.

Limiting a class to a single instance is the very definition of singleton pattern.

What's the best way to do this and avoid testability problems?

I don't think testability problems can be avoided if you limit class to a single instance. Best approach might be to forget about such requirement.

Global access isn't necessary

Then I suggest a local static variable:

void function_that_needs_a_single_instance_ever() {
    static singleton_class instance;
    // do something with your singleton
}

Upvotes: 3

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