How to implement singleton without using static/global variable? Possible?
This is an interview question...
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Why are you concerned with using the static global variable? As long as you are using the singleton method correctly, you are fine.prolink007– prolink0072010-11-05 03:08:13 +00:00Commented Nov 5, 2010 at 3:08
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3 Answers
Dependency injection is one possibility. Since your question is not specific to any programming language, I am not posting framework specific syntax (such as Ninject)
4 Comments
Samuel Neff
With DI you're just shifting the storage from a static variable to the DI container. Also, you're losing a lot of the benefits of singletons--enforced single instances. With DI you're relying on users to always use the DI framework which can internally enforce single-instance rules, but cannot prevent code outside the DI from creating additional instances.
akf
as an answer to an interview question, which itself is more of a 'lets see how the candidate thinks' type, this is good.
Samuel Neff
@akf, for an interview, it's important to be able to explain the positives and negatives of the proposed approach.
WorldIsRound
Agreed to your point of view. Since the original question was more on ways of implementing Singleton, I suggested this as one of the possibilities. The fact however remains that nothing prevents me from skipping the dependency injection framework and creating an instance of the class.
Store the singleton in a file.
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No. You need a place to store the singleton.
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