Pointers, References and Values by Michael D. Crawford Continued...
When to Return Results by Reference
Consider returning a result by reference if the value referred is certain live on after the function returns.
You can consider returning a reference result when the object referred to is not local to the function. The most important of the cases where this occurs is when you want to return a data member of the function's class, but either don't want to incur the overhead of copying the member object or you want to allow the original to be modified by the recipient. In this case, return a reference to the data member. This can be const or non-const depending on the access you wish to grant to the recipient:
An important consideration is that the object referred to must live as long as the
recipient will keep accessing it. If you call GetFoo() on an Example
object to get a reference to its mFoo member, then delete the Example
object, your reference will be invalid - using it will likely cause a crash.
I find returning reference results most useful in base class accessors that are declared protected, for use by derived classes. In this case we can be sure of the referenced object's lifetime because the base class object is destroyed after the derived parts.
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Copyright © 2000, 2001, 2002, 2005 Michael D. Crawford. All Rights Reserved.
