C++ static global non-POD: theory and practice

Question

I was reading the Qt coding conventions docs and came upon the following paragraph:

Anything that has a constructor or needs to run code to be initialized

Answer 1

C++ doesn't define the order that static initializers execute for objects in different compilations units (the ordering is well defined within a compilation unit).

Consider the situation where you have 2 static objects A and B defined in different compilation units. Let's say that object B actually uses object A in it's initialization.

In this scenario it's possible that B will be initialized first and make a call against an uninitialized A object. This might be one thing that is meant by "not at all" - an object is being used when it hasn't had an opportunity to initialize it self first (even if it might be initialized later).

I suppose that dynamic linking might add complexities that I haven't thought of that cuase an object to never be initialized. Either way, the bottom line is that static initializatino introduces enough potential issues that it should be avoided where possible and very carefully handled where you have to use it.