Re: returning references
Below is posted from a link for Stanford students in computer
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Because of the risk of misuse, some experts recommend never
returning a reference from a function or method.
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I have never heard anyone else say that it is a problem for a
function to return a reference.
"C++ Coding Standards" by Sutter & Alexandrescu. Item 42: Don't give
away your internals.
Don't volunteer too much: Avoid returning handles to internal data
managed by your class, so clients won't uncontrollably modify
state that your object thinks it owns.
For context, "handles" above is defined as non-const references, and
pointers to non-const data.
So now you have heard of at least two acknowledged experts who almost
state the same thing.
Are there really experts who object, or is this nothing other than
the commonplace observation that reference- returning is a somewhat
difficult concept that needs to be learned carefully? (I am just
learning about this now.) Assuming programmers have some degree of
competence and are able to avoid returning references to locals and
so on, what (if anything) are the pitfalls?
The only valid reference that can be returned from a non-member function
is something that either the calling code had access to anyway, or
something that is buried in a module.
The only valid reference that can be returned from a member-function is
of something that either the calling code had access to anyway, or
something that is private within the class.
In either case, if you are returning a non-const reference, then the
object returned better not have anything to do with the invariant of
that class/module or the class/module is asking for trouble
(encapsulation is broken.)