Re: The use of const reference instear of getter

From:
James Kanze <james.kanze@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Mon, 4 Aug 2008 08:17:55 -0700 (PDT)
Message-ID:
<bf365953-9c04-4c7d-96eb-ba39699472f4@z66g2000hsc.googlegroups.com>
On Aug 4, 3:52 pm, Jerry Coffin <jcof...@taeus.com> wrote:

In article <7210b453-7a0e-4af3-a159-98f7848d28dd@
34g2000hsh.googlegroups.com>, omar.ham...@gmail.com says...

[ ... ]

However, if all I am interested in when making a member
private is to disallow the modification of the value of that
member (read-only member), then how about doing the
following:

class A {
  public :
    const int& ref_to_priv_member;
    A() : ref_to_priv_member(priv_member) {
      /* Blah */
    }

  private :
    int private_member;
};

I would like to know the opinion of C++ experts on this and
if there are any side-effects of this. Also from the
perferformance point of view, isn't using this more effecient
than using a getter?

Looking forwards to hearing your opinions.


This works perfectly well, and doesn't really have any
side-effects.


With most compilers, it will increase the size of the object.
(And since the original poster mentionned performance, I expect
that with most compilers, compared to a getter, it will generate
slower code. Internally, the reference will be implemented as a
pointer, and that ain't good for optimization.)

The other problem is consistency. When you need to return
something that isn't really a member variable, you use a
function call; for the member variable, you use a reference.
Isn't that exposing internal details which the client code
should not be concerned with?

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