c++ - Safe getter to QStates -

i have class, containing qstatemachine. has couple of qstate*s.

private: qstatemachine m_machine; qstate* m_state1 qstate* m_state2 ... 

i initialize state machine in constructor, , set machine running.

as states private, want allow user subclass , altering behavior (e.g. adding transitions, change properties, connecting signals e.t.c) want add getters. don't add setters, documentation states:

removing states while machine running discouraged.

the qtcreator produces that:

qstate *myclass:state1() const {     return m_state1; } 

which seems nice.

however seems me circumvents decision on not providing setters, possible:

qstate* state = state1(); *state = qstate([...]); 

which understanding removes original state1 , overwrites new state.

so thought return const qstate* instead.

const qstate* myclass::state() const {     return m_state1; } 

which seems work (the example above throw compiler error). new c++ not sure know have done there , if there other implications.

what right way achieve desired behavior?

if want user able retrieve state, unable affect retrieved state object, can consider using constant reference return type

const qstate& myclass::state() const {     return *m_state1; } 

in case, returned object of type const qstate&, cannot assigned or receiver object of non-const function call. right way achieve behavior, returning const qstate* result in identical behavior, require de-reference -> each access.

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