Date: Fri, 12 Dec 1997 02:42:07 +0000 (GMT) From: Terry Lambert <tlambert@primenet.com> To: j_mini@efn.org Cc: jkh@time.cdrom.com, ksmm@cybercom.net, freebsd-hackers@FreeBSD.ORG Subject: Re: Why so many steps to build new kernel? Message-ID: <199712120242.TAA07290@usr02.primenet.com> In-Reply-To: <19971211021856.61158@micron.mini.net> from "Jonathan Mini" at Dec 11, 97 02:18:56 am
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> 3) C++ does not implement data hiding. Sure, you have opaque structs,
> but you cannoy make an opaque class. That is, you cannot have a class
> defined where you know how to interface with the functions, but not
> the details of the internal data. Because you have to define the
> private data within the same scope as the public interface, private
> datatypes aren't possible.
This is incorrect.
global.h:
#define interface struct /* no virtual destructor needed*/
myOpaqueClass.h:
interface myOpaqueClass {
virtual int function1( int arg1, char *arg2) = 0;
virtual int function2( char *arg1) = 0;
};
extern myOpaqueClass *createOpaqueClassObject();
myImplementationClass.cc
#include "global.h"
#include "myOpaqueClass.h"
class myImplementationClass : public myOpaqueClass {
private:
/*
* Private data not defined in the scope of the
* public interface.
*/
int somedata;
public:
myImplementationClass(); /* constructor*/
~myImplementationClass(); /* destructor*/
int function1( int arg1, char *arg2);
int function2( char *arg1);
};
/*
* Public interface; use shared object technology to select
* between implementation class instances for a given opaque
* class...
*/
myOpaqueClass *
createOpaqueClassObject()
{
myImplementationClass *instance;
intstance = new myImplementationClass;
return( (myOpaqueClass *)instance;
}
/*
* constructor
*/
myImplementationClass::myImplementationClass()
{
}
/*
* destructor
*/
myImplementationClass::myImplementationClass()
{
}
/*
* implementation class specific implementation of pure
* virtual base class interface "function1"...
*/
int
myImplementationClass::function1( int arg1, char *arg2))
{
...
}
/*
* implementation class specific implementation of pure
* virtual base class interface "function2"...
*/
int
myImplementationClass::function2( char *arg1)
{
...
}
Terry Lambert
terry@lambert.org
---
Any opinions in this posting are my own and not those of my present
or previous employers.
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