c++ - Why provide two get functions -

c++ - Why provide two get functions -

class t {}; class accesst { public: boost::shared_ptr<const t> gett() const {return m_t;} boost::shared_ptr<t> gett() {return m_t;} private: boost::shared_ptr<t> m_t; };

question> saw lots of similar codes above in legacy project. don't understand point of doing so. why not provide next instead:

class t {}; class accesstmodified { public: boost::shared_ptr<t> gett() const { homecoming m_t; } private: boost::shared_ptr<t> m_t; };

the initial argument may boost::shared_ptr<const t> gett() const not allow const object modifies t accident. if case, practice such functions should provide 2 versions? me, sense tedious!

you correct: purpose of boost::shared_ptr<const t> gett() const ensure const objects can't modify t accident.

in c++, known const correctness , considered c++ design. said, results in getters having 2 versions (a const , non-const version). can tedious (although it's not bad 1 time used it), results can quite useful. const correctness lets declare functions like

void dosomething(const accesst& item);

that promise not modify item compiler throws error if dosomething that's declared perchance modifying item.

although const correctness considered c++ design, developers decide overhead of having declare const , non-const versions of functions more problem it's worth.

the c++ faq has a whole section on const correctness, if you're interested in more information.

c++ boost