Which Singleton library in BOOST do you choose?

Question

Google results say there are more than 1 singleton template/baseclass in boost, which one do you suggest?

Answer 1

You shouldn't use the singletons in boost, they are for internal purpose only (see the "detail" folders of separate libes). That's why you don't have a Singleton library (yet) exposed on the boost website.

A singleton class is very simple to implement but there are many variants that are useful in specific cases so you should use something that fit what you think a singleton should behave like.

Now, there is other libraries providing singleton, the most generic being Loki. But it could blow your mind ;)

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Update : There is now a proposed library called Singularity that is meant to provide non-global singleton (with option to make it global) that forces you to have clear creation and destruction points of the object.

See the review request : http://boost.2283326.n4.nabble.com/Review-Request-Singularity-tt3759486.html

Some boost devs seems to consider using it instead of some hacks, but C++11 makes makeing a class Singleton easier than before so it will depends on the review.

Answer 2

My version of boost has following singleton.hpp headers:

C:\boost_1_38_0\boost\pool\detail\singleton.hpp
C:\boost_1_38_0\boost\serialization\singleton.hpp
C:\boost_1_38_0\boost\thread\detail\singleton.hpp

I haven't used any of those, but I'd probably stay away from the ones in detail directories.

Anyway, http://torjo.com/tobias/index.html#boost_utility_singleton.reference.singleton looks like one to use, but it doesn't seem to be really a part of boost (not accepted yet?).