WORKSPACE_A.cpp/.h
Class WORKSPACE_A {
static AAA a;
}
WORKSPACE_B.cpp/.h
Class WORKSPACE_B {
static BBB b;
}
How do I know whether AAA a , or BBB b is initialized first.
Thank you
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you can't, you shouldn't care (you should just imagine that they are initialized at the same time) – Exceptyon Jan 15 '14 at 11:08
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1@Exceptyon Perhaps BBB b; has to call WORKSPACE_A:a in BBB::BBB() constructor – Denny Jan 15 '14 at 11:09
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You should initialize the static variables in a cpp-file in any order you need. For example, `int WORKSPACE_A::a = 1; int WORKSPACE_B::b = 2;`. Also you may move all initialization in a method and use `#pragma`s to run it at initialization. The pragmas may vary depending from your compiler: `#pragma startup` and `#pragma init_seg` are to name a few. – Stan Jan 15 '14 at 11:40
4 Answers
1
As stated by @Denny the issue is probably dependencies between the twos.
I think the way to go is having pointers and explicit static init functions:
class WORKSPACE_A {
static AAA* a;
public:
static void initialize() { /* a = ... */ }
}
class WORKSPACE_B {
static BBB* b;
public:
static void initialize() { /* b = some_f(WORKSPACE::a) */ }
}
Exceptyon
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I know it could be fixed by your above code , that's no way to order initialzation right ? , can I order file when linking *.o ("cc workspace_a.o workspace_b.o to solve this problem ? – Denny Jan 15 '14 at 11:16
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could be... depends on how your linker is implemented I guess... I wouldn't rely on that anyway: one day you'll forget to order the .o in a makefile, or change compiler – Exceptyon Jan 15 '14 at 11:31
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This is called the "static initialization order fiasco"
A common approach is to use initialize-on-first-use within an "accessor function"
class WORKSPACE_A {
AAA& getA()
{
static AAA a;
return a;
}
}
Of course, you still have "static destruction order fiasco" to contend with... This can be mitigated by dynamically allocating the AAA in the accessor (static AAA *a = new AAA;) but then the object simply never gets destructed!
Roddy
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Order of initialization of global variables (or static) are guaranteed in each translation unit. But not guaranteed in different translation units.
See this answer to the question C++ global initialization order ignores dependencies?.
