C++: Design objects to model unique items in a system

Question

I would like to model a group of items (people) where each individual has a set of unique characteristics... If I pass around my objects willy-nilly then copy constructors, etc. will cause my objects to diverge such that Object A will eventually have multiple different versions floating around, A` returned from method X, A`` returned from method Y and so forth. Which design pattern will help me ensure that if I pass around objects to various functions, that I'll be sure to always be acting on the unique representation of each given object. Thanks.

You can protect classes against being copied and enforce pointer/reference semantics, as mentioned. Note also the existence of the convenience class [boost::noncopyable](http://stackoverflow.com/questions/7823990/what-are-the-advantages-of-boostnoncopyable) — HostileFork says dont trust SE, Jan 17 '13 at 16:31

score 2 · Accepted Answer · answered Jan 17 '13 at 16:28

2

Either use smart pointers or just pass by reference. I'm not really sure what more advanced design pattern you're expecting to need.

answered Jan 17 '13 at 16:28

djechlin

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score 2 · Answer 2 · answered Jan 17 '13 at 16:29

2

As others have said, pointers, smart pointers, or pass-by-reference.

If you're worried about forgetting, you can make the copy constructor private. That way, passing by value will be a compiler error.

answered Jan 17 '13 at 16:29

dspeyer

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score 2 · Answer 3 · answered Jan 17 '13 at 16:30

Just don't make copies of your objects. Store them all in a central location (using a container like std::vector or std::unordered_map) and then pass references to your various functions. For example:

void MutatePerson( Person& object );
void InspectPerson( const Person& object );

C++: Design objects to model unique items in a system

3 Answers3