Question

I have a template class where typename is a pointer to a function:

CHook<NTSTATUS(__stdcall*)(PHANDLE,ACCESS_MASK,POBJECT_ATTRIBUTES,HANDLE,PCLIENT_ID,PCONTEXT,PUSER_STACK,BOOLEAN)> hZwCreateThread;

Now I call them like hZwCreateThread.Call()(…params…); but I want to make it hZwCreateThread(…params…) using () operator overloading.
This code:

const FuncType operator()() { return m_OrigFunc; };

Makes it work only in such way: hZwCreateThread()(…params…). How to make it work as I wrote above?

Answer 1

You can use a conversion operator.

template <typename F>
struct CHook {
    F m_OrigFunc;
    CHook (F func) : m_OrigFunc(func) {}
    operator F () const { return m_OrigFunc; }
};

This would allow code like this:

CHook<int(*)(const char *,...)> chook(printf);
chook("%s\n", "Hello world!");