Is the pImpl idiom really used in practice?

Question

I am reading the book \"Exceptional C++\" by Herb Sutter, and in that book I have learned about the pImpl idiom. Basically, the idea is to create a structure for the p

Answer 1

Other people have already provided the technical up/downsides, but I think the following is worth noting:

First and foremost, don't be dogmatic. If pImpl works for your situation, use it - don't use it just because "it's better OO since it really hides implementation" etc. Quoting the C++ FAQ:

encapsulation is for code, not people (source)

Just to give you an example of open source software where it is used and why: OpenThreads, the threading library used by the OpenSceneGraph. The main idea is to remove from the header (e.g. ) all platform-specific code, because internal state variables (e.g. thread handles) differ from platform to platform. This way one can compile code against your library without any knowledge of the other platforms' idiosyncrasies, because everything is hidden.