Reputation: 143
I'm having problems writing a wrapper class using the boost::locale::date_time library. Specifically, I cannot create a global object from my class, though everything works fine other than that.
Here's relevant sample code:
// DateTimeWrapper.h
#include <boost\\locale\\date_time.hpp>
#include <boost\\locale.hpp>
class DateTimeWrapper
{
public:
DateTimeWrapper();
~DateTimeWrapper();
// ... Other methods...
protected:
boost::locale::date_time* m_date_time;
static void Init_Global_Locale();
static bool m_Global_Locale_Initialized;
};
// DateTimeWrapper.cpp
bool DateTimeWrapper::m_Global_Locale_Initialized = false;
DateTimeWrapper::DateTimeWrapper()
{
Init_Global_Locale();
// The following line will work for the local object,
// but throws a std::bad_cast exception for the global object
m_date_time = new boost::locale::date_time;
}
DateTimeWrapper::~DateTimeWrapper()
{
delete m_date_time;
}
void DateTimeWrapper::Init_Global_Locale()
{
if (!m_Global_Locale_Initialized)
{
boost::locale::generator gen;
std::locale l = gen("");
std::locale::global(l);
m_Global_Locale_Initialized = true;
}
}
// This object throws a std::bad_cast exception. Code runs normally if I comment out the following line.
DateTimeWrapper global_date_time_object;
int main()
{
// This object works just fine
DateTimeWrapper local_date_time_object;
// Do stuff with local_date_time_object...
return(0);
}
As you can see in the code, I use a static member to make sure the global locale is initialized the first time a DateTimeWrapper object is created. Normally, this prevents a std::bad_cast exception from being thrown when I create my boost::locale::date_time member. However, I still receive the exception from that line when the first DateTimeWrapper object created is a global instance.
Note that stepping through the debugger, I can confirm that all lines in the Init_Global_Locale() method are run during construction of the global object. This sample code also declares DateTimeWrapper::m_Global_Locale_Initialized before it declares global_date_time_object, within the same source file, so I know that order-of-initialization is not the problem here (confirmed by stepping through with the debugger anyhow).
So why does the code work for local objects but not global objects, even though I can see all lines of code are run through, in the correct order, for both versions?
Upvotes: 1
Views: 253
Reputation: 393694
I cannot reproduce the error (with the code shown in a single TU).
My hunch is that you have void DateTimeWrapper::Init_Global_Locale()
and m_Global_Locale_Initialized
defined in another translation unit, which lands you in SIOF (static initialization order fiasco).
Besides, there are numerous complexities about your types inviting errors (using non-owned pointers, not following Rule-Of-Zero/Three/Five). I'd write it much simpler, using C++11's function local static initialization:
#include <boost/locale.hpp>
#include <boost/locale/date_time.hpp>
struct EnsureLocaleBase {
EnsureLocaleBase() { Init(); }
private:
static bool Init() {
static auto const s_init = [] {
boost::locale::generator gen;
std::locale l = gen("");
std::locale::global(l);
return true;
}();
return s_init;
}
};
class DateTimeWrapper : EnsureLocaleBase {
boost::locale::date_time m_date_time;
};
DateTimeWrapper global_date_time_object;
int main() {
DateTimeWrapper local_date_time_object;
}
Function local statics don't suffer SIOF and also are thread-safely initialized.
Upvotes: 0