I am trying to use boost factory and I am experiencing the following problem. All I am trying to do is having a bunch of derived classes to have a mechanism that will be initializing the derived class that is matched with a corresponding string. To begin with I have the following base class called name NetWorkBlock,
NetWorkBlock.h
class NetWorkBlock {
protected:
typedef boost::function<NetWorkBlock * ()> NetWorkFactory;
//definition of the function that will be used for the factory
public:
NetWorkBlock();
virtual ~NetWorkBlock();
//some basic functionalities that not related to the factory
and thus not mentioned
static std::map<std::string,NetWorkBlock::NetWorkFactory>& f_factory();
//static function that initializes and returns the map
};
NetWorkBlock.cpp
NetWorkBlock::NetWorkBlock() {
} //empty constructor
NetWorkBlock::~NetWorkBlock() {
} //empty deconstructor
std::map<std::string,NetWorkBlock::NetWorkFactory>& NetWorkBlock::f_factory()
{
static std::map<std::string,NetWorkBlock::NetWorkFactory>* ans =
new std::map<std::string,NetWorkBlock::NetWorkFactory>();
return *ans;
} //initialization of map
Moving on here is how I define things in the the derived class BusNetworkBlock (note ofcourse there are more derived classes expected to be defined later, but in the current moment I work with a single derived class to manage to have things working):
BusNetworkBlock.h
class BusNetworkBlock {
public:
BusNetworkBlock();
virtual ~BusNetworkBlock();
//some basic functionalities that not related to the factory
and thus not mentioned
private:
/* Very small, "fake" class _initializer. Its only meaning is to define a
static member _init that is initialized at the very beginning of the
main(). Hence the constructor is called, and the constructor registers
the BusNetworkBlock class into the (static) NetWorkBlock::f_factory. */
static class _init {
public:
_init() {
NetWorkBlock::f_factory()["LoadCurve"] = boost::factory<BusNetworkBlock *>();
}
}_initializer;
};
BusNetworkBlock.cpp
BusNetworkBlock::BusNetworkBlock() {
} //empty constructor
BusNetworkBlock::~BusNetworkBlock() {
} //empty deconstructor
/* The definition of the bodies of the funcionalities of the class that are not mentioned here since they are not connected with the factory */
BusNetworkBlock::_init BusNetworkBlock::_initializer;
/* Ensure that the static member _initializer is initialized, so that
BusNetworkBlock is registered into NetWorkBlock::f_factory. */
Now in an other separate class under the name UCBlock I try to use the factory in order to initialize properly the derived NetworkBlock class based on a string I receive in the following way:
UCBlock.h
class UCBlock {
public:
UCBlock(std::istream& inStream); //the received instream
virtual ~UCBlock();
//some basic functionalities that not related to the factory
and thus not mentioned
NetWorkBlock * Network; /*defining a pointer of the base class NetWorkBlock
that want to initialize properly via the factory */
};
UCBlock.cpp
UCBlock::UCBlock( std::istream& inStream ) {
inStream >> network; //setting the string of network the corresponding factory
Network = NetWorkBlock::f_factory()[network](); // set the corresponding object via factory **here is where the problem arises**
}
And the problem arises when I try to use the factory to proper initialize the derived class of NetWorkBlock. I receive the following error:
terminate called after throwing an instance of 'boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::bad_function_call> >'
what(): call to empty boost::function
Aborted (core dumped)
Now I have ofcoruse tried to check this thing online but didn't manage to come up with a solution and that's why I would really appreciate any kind of help here, since I am really stacked here. (Note also that I checked that the string I receive is correct and matches with "LoadCurve").
