C++ get method - returning by value or by reference

c++ reference return-value return-value-optimization
Yippie-Ki-Yay picture Yippie-Ki-Yay · May 30, 2010 · Viewed 10.7k times · Source

I've go a very simple question, but unfortunately I can't figure the answer myself.

Suppose I've got some data structure that holds settings and acts like a settings map. I have a GetValue(const std::string& name) method, that returns the corresponding value.

Now I'm trying to figure out - what kind of return-value approach would be better. The obvious one means making my method act like

std::string GetValue(const std::string& name) const

and return a copy of the object and rely on RVO in performance meanings.

The other one would mean making two methods

std::string& GetValue(...)
const std::string& GetValue(...) const

which generally means duplicating code or using some evil constant casts to use one of these routines twice.

#Q

What would be your choice in this kind of situation and why?

Answer

fredoverflow picture fredoverflow · May 30, 2010

That depends on the usage. Should GetValue("foo") = "bar" make sense? In that case, return by value does not do what you want.

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