Re: returning references

From:

"Daniel T." <daniel_t@earthlink.net>

Newsgroups:

comp.lang.c++

Date:

Fri, 04 Jan 2008 19:57:13 -0500

Message-ID:

<daniel_t-1E3F9E.19571204012008@earthlink.vsrv-sjc.supernews.net>

James Kanze <james.kanze@gmail.com> wrote:

On Jan 4, 8:36 pm, "Daniel T." <danie...@earthlink.net> wrote:

Changing a function from returning const-reference to returning const
object can't break any existing clients.

IE. if I have this:

class Object {
public:
const Foo& getFoo() const;
};

and later, I don't want to store a Foo, I can easily change
the class to:

class Object {
public:
const Foo getFoo() const; // I could even dump the first const
};

and clients will not be affected. As I understand it, the two
returns are as interchangeable as if they were function
parameters.

Unless, of course, the type doesn't support copy. Or if the
client takes the address of the return, and later uses it. Or
any number of other cases as well. The lifetime of the object
is *not* the same.

Well, in the former case, Object has no choice but to return a reference
(or pointer.) In the latter case... I don't concern myself with such
pathological behavior by the client. I don't guarantee that state
returned by const reference will last past the next sequence point in
any case.