In his "Thinking in C++" (Chapter 10) Eckel describes a technique that was pioneered by Jerry Schwarz to solve the fiasco.
He says that if we want to initialize x to 100 and y to 200 and share them among all translation units, we create an Initializer.h that looks like this:
extern int x;
extern int y;
class Initializer {
static int initCount;
// if (initCount++ == 0) x = 100 & y = 200
/* ... */
};
static Initializer init;
And in implementation file we have
#include "Initializer.h"
int x;
int y;
int Initializer::initCount;
and Eckel says that "static initialization (in implementation file) will force all these values to zero".
Let me consider the following case: the compiler processes the implementation file after some other file with that header included (it means that x and y have been already set to 100 and 200 in that other file). The compiler sees int x
, so what will it do? Will it set x and y to zero eliminating initialization and all possible changes in previous files? But if it does, then initCount
will also be set to zero, breaking down the whole technique.
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