Re: Inheritance: Can the base class access a function in the class which is inheriting from it?

From:
red floyd <no.spam@here.dude>
Newsgroups:
comp.lang.c++
Date:
Thu, 13 Mar 2008 22:23:57 -0700
Message-ID:
<BYnCj.1006$LV5.841@newssvr19.news.prodigy.net>
ngoonee@gmail.com wrote:

Hi all,

My intent is to code some algorith which repeatedly applies a certain
comparison function in C++. The algorithm itself works fine, but I'm
searching for easy ways to select the comparison function to be
applied, preferably at run-time (ie. no preprocessor defines).

A very simplified example of the idea I had:-

class baseclass {
private:
  virtual int compare(int a,int b);
public:
  int do_something(int a, int b) {
    return compare(a,b);
  }
};

class class2:public baseclass {
private:
  int compare(int a,int b) {
    return (b-a);
  }
public:
};

class class1:public baseclass {
private:
  int compare(int a,int b) {
    return (a-b);
  }
public:
};

Hence, if I create an instance of class1 and call the function
do_something, I'd like it to access the compare() function within
class1. Obviously, however, it doesn't work as is, meaning the method
I'm trying is not legal.

1. Could anyone suggest a legal way of doing what I'm trying to
accomplish, besides simply copy-pasting the whole code of
do_something() into a seperate class?

2. Is there any other way besides class inheritance to accomplish the
above?


What doesn't work?
The only problem that I can see is that you haven't implemented
baseclass::compare. Either provide an implmeentation or declare it as
pure virtual.

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