Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!apple!vsi1!daver!tscs!tct!chip
From: chip@tct.uucp (Chip Salzenberg)
Newsgroups: comp.lang.c++
Subject: Re: private base classes (was Nonvirtual base classes in MI)
Message-ID: <27B94BB0.5A0A@tct.uucp>
Date: 13 Feb 91 14:22:40 GMT
References: <1174@zinn.MV.COM> <64173@brunix.UUCP> <1991Feb8.220931.251@odin.corp.sgi.com>
Organization: Teltronics/TCT, Sarasota, FL
Lines: 33

According to linton@sgi.com (Mark Linton):
> If you have a real example of "convenient" private inheritance,
> I'd be interested in seeing it.

In a real application I have two classes, SqlStmt and SqlCursor.
SqlStmt is a private base class of SqlCursor.  I would have made it
public, but to maintain internal consistency I can allow only one
member function of SqlStmt public, namely, SqlStmt::in().  However,
SqlStmt::in() is actually several overloaded functions.  Thus the
declaration:

    class SqlCursor : private SqlStmt {
      public:
        SqlCursor();
        ~SqlCursor();

        SqlStmt::in;

        // other declarations...
    };

This declaration conveniently makes all the SqlStmt::in() functions
public without needing to name them all.

The use of inheritance instead of a SqlStmt member variable also
implies that the member functions of SqlCursor can call member
functions of SqlStmt without specifying "member.func()".

Both of these aspects are convenience wins.
-- 
Chip Salzenberg at Teltronics/TCT     <chip@tct.uucp>, <uunet!pdn!tct!chip>
 "I want to mention that my opinions whether real or not are MY opinions."
             -- the inevitable William "Billy" Steinmetz