c++ - Are there any alternatives to making const version of class? -

c++ - Are there any alternatives to making const version of class? -

in c++ i'm facing situation when need prepare const , non-const version of class in analogy const_iterator , iterator standard library.

class const_myclass { public: const_myclass(const int * arr): m_arr(arr) { } int method() const; //does m_arr without modifying private: const int * m_arr; } class myclass { public: myclass(int * arr): m_arr(arr) { } int method() const; //does m_arr without modifying void modify(int i); //modify m_arr private: int * m_arr; }

the problem need repeat whole code of const_myclass in myclass , distribute changes in api both classes. inherit const_myclass , const_casts, isn't perfect , pretty solution. still when want pass const_myclass instance reference looks moronic:

void func(const const_myclass & param)

instance param marked 2 "consts", , has const methods...

this const constructors handy, there existing alternatives?

some utilize examples explain problem better:

//ok modify info void f(int * data) { myclass my(data); my.modify(); ... } //cant modify data, cant utilize myclass void fc(const int * data) { const_myclass my(data); int = my.method(); ... }

you can create template class deed base, this:

template<typename t> class basic_myclass { public: basic_myclass(t * arr) :m_arr(arr) {} int method() const; //does m_arr without modifying private: t * m_arr; };

then, const version, since doesn't add together anything, can utilize typedef:

typedef basic_myclass<const int> const_myclass;

for non-const version, can inherit:

class myclass : public basic_myclass<int> { public: using basic_myclass::basic_myclass; // inherit constructors void modify(int i); //modify m_arr };

c++ const-correctness