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/*
* The Unix Channel
*
* by Michel Beaudouin-Lafon
*
* Copyright 1990-1993
* Laboratoire de Recherche en Informatique (LRI)
*
* Messages
*
* $Id$
* $CurLog$
*/
#include "cplus_bugs.h"
#include "Message.h"
/*?class UchMessage
\typ{UchMessage} is the abstract base class for messages.
Each subclass must redefine the virtual functions \fun{WriteTo} and \fun{ReadFrom},
so that messages can be added to and retrieved from buffers.
?*/
/*?nodoc?*/
UchMessage :: UchMessage ()
{
}
/*?nodoc?*/
UchMessage :: ~UchMessage ()
{
}
/*?
This virtual function must write a message into a buffer.
Usually, the implementation of this function in a derived class starts by calling
the same function of its base class, because a derived class inherits the fields
of its base class and adds its own fields.
Data is usually appended to the buffer by the \fun{UchMsgBuffer::Append}
functions or \fun{operator $<<$}.
The default implementation does nothing.
?*/
void
UchMessage :: WriteTo (UchMsgBuffer&)
{
// nothing
}
/*?
This virtual function must extract data from the buffer to create the message.
At most \var{len} bytes should be read from the buffer.
Usually, the implementation of this function in a derived class starts by calling
the same function of its base class, because a derived class inherits the fields
of its base class and adds its own fields.
Data is usually retrieved from the buffer by the \fun{UchMsgBuffer::Get}
functions or \fun{operator $>>$}.
The default implementation does nothing.
?*/
void
UchMessage :: ReadFrom (UchMsgBuffer&, lword)
{
}
/*?
This virtual function can be redefined in derived classes to support the handling of messages
after they have been loaded from a buffer. The function \typ{MyClient}::\fun{NewMessage}
may then look like:
\begin{ccode}
void
MyClient :: NewMessage (UchMsgBuffer& buffer, bool ask)
{
MyRequest* m = 0;
lword type;
buffer.MsgPeek (&type);
switch (type) {
case MyFirstReqType:
m = new MyFirstRequest;
break;
case ...
...
}
if (m) {
buffer.Get (m);
m->Activate (*this);
return TRUE;
}
return FALSE;
}
\end{ccode}
However, this virtual function is only provided as a facility and is not used
by \uch. Redefining it is not mandatory.
?*/
void
UchMessage :: Activate (UchMsgStream&)
{
}
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