NetNews Offline 2/NetNews Offline Volume 2.iso/news/comp/lang/c++-part1/1981

Internet Message Format | 1996-08-06 | 2.2 KB

Path: news.th-darmstadt.de!news!enno
From: [e-mail] (Enno Sandner)
Newsgroups: comp.lang.c++
Subject: Re: Overloading conversion
Date: 14 Jan 1996 19:42:35 GMT
Organization: Fachbereich Informatik, TH Darmstadt
Distribution: world
Message-ID: <[e-mail]>
References: <4d934v$[e-mail]>
    <[e-mail]>
    <[e-mail]>
NNTP-Posting-Host: kitz.intellektik.informatik.th-darmstadt.de
In-reply-to: [e-mail]'s message of Sun, 14 Jan 1996 17:05:03 GMT

In article <[e-mail]> [e-mail] (Mike Rubenstein) writes:

   [e-mail] (Enno Sandner) wrote:

   |>In article <4d934v$[e-mail]>
   [e-mail] (Hanna Dang) writes:
   |>
   |>   Is there a way to overload functions such that certain
   |>   functions are called depending on the context the object are
   |>   used. For example,
   |>
   |>   class T {
   |>     public:
   |>       int& int_value() { modified = TRUE; return value;}
   |>       int int_value() {return value;}
   |>    private:
   |>       int value;
   |>       int modified;
   |>   }
   |>
   |>
   |>   ...
   |>
   |>   T a;
   |>   int test = a + 6 // int int_value should be called;
   |>   a = 20 // int& int_value should be called.
   |>
   |>   However, this does not work because in both case int& int_value
   |>   is called.  Is there another way to find out if value is changed
   |>   or it's just inspected.
   |>
   |>Yes -- make the latter 'int_value' a const member-function, ie.
   |>
   |>        int int_value() const {return value;}

   Have you tried this?  If so, what compiler?  I want to make sure I
   avoid it.

   The decision as to whether to call the const or non-const version of a
   member function is based on whether the class object is const, not on
   which side of the equal sign it appears.  In both cases above, the
   non-const version will be called since a is not const.

Yep, you are correct -- my previous posting was completly rubbish.

        Enno