Thread: OO Design regarding returning a value from an object

Quick question regarding OO design:

If I had a class that contains a list of items that are defined within a struct. The struct in this case does not contain any allocated memory, so a direct copy to another struct of this type should be possible. Would it be more efficient (and correct) to:

a: use a method to return the value of one of the items members and thus have one corresponding method for each member of the struct.

b: use a single method to return a copy of the struct that can either be copied to a temporary struct type, or directly referenced from the returning value. i.e.

Code:

result = object.mymethod().structmember;

Thanks.

I would return the whole struct, so you only have to do one function call to get all your data. It's probably more efficient.

Yeah that is what I was thinking. Excellent, thanks!

c) Pass a pointer to the struct?

result = object.GetStructPointer()->structMemberA;

When you pass by value, the object needs copying and that's inefficient--especially for large objects.

So I could then:

Code:

STRUCTTYPE *foobar;

foobar = object.mymethod();

And play with the members through the pointer foobar. Cool

STRUCTTYPE *foobar;

foobar = object.mymethod();

Now I'm not so certain that's the right thing to do. By doing that you expose your class data member: it can be changed through the pointer, so essentially you've made it public. Maybe b) is the better design choice--returning an object will pass it by value, so changes can't be made to the struct members. If you don't need to change the struct members, I think that would be best afterall.

Yeah, that is a good point, I don't really want that struct to be modified outside of the scope of the object. Ok - thanks.