Flexible templated function class and related utilities that avoid dynamic memory allocation without limiting functionality

Dependents:   SimpleHTTPExample

FuncPtr provides a flexible templated function class and related utilities while avoiding dynamic memory allocation and avoiding limited functionality.

FuncPtr provides an intuitive template interface:

FuncPtr<void(const char *)> func(puts);
func("hello!\n"); // prints hello!

Several function types are supported by FuncPtr:

// Simple C functions
void func();
FuncPtr<void()> fp(func);

// C++ Methods
struct Thing { void func(); };
Thing thing;
FuncPtr<void()> fp(&thing, &Thing::func);

// C functions with context
void func(Thing *);
FuncPtr<void()> fp(&thing, func);

// Function objects
struct Thing { void operator()(); };
Thing thing;
FuncPtr<void()> fp(&thing);

There is no dynamic memory allocation, managing memory is placed entirely on the user. More advanced function manipulation can be accomplished with statically allocated classes:

// Function binding
Binder<void(const char *), const char *> bind(putc, "hi!");
bind(); // prints hi!

// Function composition
Composer<int(const char *), const char *(int)> comp(puts, itoa);
comp(10); // prints 10

// Function chaining
Chainer<void(const char *), 2> chain;
chain("hi!\n"); // prints hi! twice

FuncPtr allows easy support of a large range of function types in C++ APIs with very few lines of code:

class Thing {
    // The following two methods are sufficient for supporting 
    // every supported function type
    void attach(FuncPtr<void()> func) {

    template<typename T, typename M>
    void attach(T *obj, M method) {
        attach(FuncPtr<void()>(obj, method));

    FuncPtr<void()> _func;

Additionally, FuncPtrs have several utilities for easy integration with C APIs:

// C style callbacks
void register_callback(void (*callback)(void *), void *data);

register_callback(&FuncPtr<void()>::thunk, &func);

// C style functions without context
void register_callback(void (*callback)());

Thunker thunk(func);

// mbed style callbacks
void register_callback(T *obj, void (T::*M)());

register_callback(&func, &FuncPtr<void()>::call);