Is this possible?
static bool initialize()
{
TRC_SCOPE_INIT(...);
...
}
static bool initialized = initialize();
To make a very long story short, I need to call a series of macros (to initialize debugging messages) as early as possible (before thread X is started, and I don't have the ability to know when thread X is started).
If you're using GCC (or clang), you can use __attribute__((constructor)):
static bool initialized = false;
__attribute__((constructor))
static void initialize(void) {
initialized = true;
// do some other initialization
}
int main(int argc, char **argv) {
// initialize will have been run before main started
return 0;
}
When I originally looked at the question, it was tagged both C and C++. The code could be C or C++ because bool is a type in C99 and C11, just as it is in C++ (almost; in C, you need the <stdbool.h> header to get the name bool).
The answers for the two tags are:
In C++, yes.
In C, no.
They are not the same language. If you need a demonstration, this is as good an example as any.
c when it was originally posted. @KingsIndian added the c++ tag because of the bool, but I reverted that edit because bool is valid in C99 and there was no indication from the original post that it was anyhow C++ related.
This should be alright provided the "stuff" you are initializing is defined in the same translation unit as the call to the function that initializes it. In addition, it must be defined above the call site. Otherwise you risk undefined behavior due to use of uninitialized values.
One way to get around this is to use a pointer instead. A statically initialized pointer is compiled into the executable image, so there's no risk of undefined behavior if it's used by statics defined in other translation units. In your static initialization function you dynamically allocate the "stuff" and set the pointer to point to it so you can access it later.
(Since you mentioned threads, I'm going to assume you have POSIX thread functions at your disposal.)
The pthread_once function exists for this exact purpose. Anywhere you need to be sure initialize has already been called, write:
pthread_once(&init_once, initialize);
where init_once is defined with static storage duration, and possibly with external linkage if needed, as pthread_once_t init_once.
pthread_once(3)in yourmain()routine?