Question about boost::function

[GliderPro]

I'm messing around with boost function and I came up with the following code. This isn't much different than using a typedef to declare a function pointer so I'm probably doing something wrong. boost::function is supposed to make things cleaner, right?

Will someone show me the proper way to use boost::function?

boost::function< int (const char *) > impPyRun_SimpleString;
boost::function< int () > impPy_Initialize;
boost::function< int () > impPy_IsInitialized;
boost::function< PyGILState_STATE () > impPyGILState_Ensure;
boost::function< void (PyGILState_STATE) > impPyGILState_Release;

void InitFunctionPointers()
{
  impPyRun_SimpleString = (int (*)(const char *))GetProcAddress(GetModuleHandleA("python25"), "PyRun_SimpleString");
  impPy_Initialize = GetProcAddress(GetModuleHandleA("python25"), "Py_Initialize");
  impPy_IsInitialized = GetProcAddress(GetModuleHandleA("python25"), "Py_IsInitialized");
  impPyGILState_Ensure = (PyGILState_STATE (*)())GetProcAddress(GetModuleHandleA("python25"), "PyGILState_Ensure");
  impPyGILState_Release = (void (*)(PyGILState_STATE))GetProcAddress(GetModuleHandleA("python25"), "PyGILState_Release");
}

[pendra]

The purpose of boost::function is to abstract a function pointer from a specific, precise function signature to any function signature for which conversion operators have been defined. It is only interesting when you want to specify function pointers that will point at different functions during their lifetimes, and you want to allow for type conversions and such in the functions they point at.

So for example, if you have a function pointer void (*)(FizzWidget &a) , then it can only point at a function that takes a FizzWidget reference and returns void. With a boost::function object, on the other hand, you can point it at a function which takes any object that can be converted to a FizzWidget, so it's more flexible.

This flexibility is useful if you're say, writing a sort function that takes a comparator function pointer as an argument and you don't want the user of your sort function to have to nitpick about whether the comparator funciton they provide takes references or pointers or shared ptrs or whatever.

In your case where the function pointers always point at the same thing, it doesn't really help. I would just use a typedef.

[GliderPro]

Thanks for the reply. That clears things up.