//  File:   REGWIZ.TXT

//                                                   September 20, 1993
//                                                   Fairfield, Iowa

//          Aerosoft  (R)  Register Wizard            Version 1.0
//          Copyright (c)  Aerosoft 1993     All rights reserved.

//          This software source code is FREEWARE.  You may be use the
//          source code or redistribute the source code free of charge.
//          However, you cannot sell this source code or any alteration of
//          the source code.

This file documents some design notes about the program.  See file REGWIZ.MAN 
for a description of the operation of the REGWIZ program.  Before reviewing
this document please read REGWIZ.MAN for an explanation of the concept of a
Register Channel.  Note that an object listening to a channel is called a
server while an object sending data is called a client.

REGWIZ reads an input file specifying register channels and it generates
four files that can be used to implement these channels.

This translation is done in two steps:  the register channel specs are
deciphered and stored in a database.  The channel specs database is then
used to generate the output files.

REGWIZ uses two principle objects to decipher the channel specs: InStream 
and ChannelSpecs.  InStream reads each channel spec entry into a buffer
and provides parsing member functions for extracting tokens from an entry.
There are three kinds of tokens: numbers, labels, and 1-char delimiters.
ChannelSpecs provides a database holding each deciphered channel entry.

A deciphered channel spec consists of six parts:

    return type specifier  (only int, long, float, double, and void are legal)
    function name
    proto-list             (the argument list including the arguments' type
                            specifiers)
    arg-list               (a list of argument names without type specifiers)
    default return value
    max receivers          (the max number of objects that can be connected to
                            the channel)
                            
Member function GetNextChannelSpec deciphers a spec.  It relies upon the
parsing functions of InStream to do this.  It scans left to right looking for
each component of a channel spec. 

NOTE: InStream skips nested parenthesis that may be found inside and argument list.
      This simplifies the work that GetNextChannelSpec must do.
      
Once the channel specs have been deciphered, code generation is a simple matter
of taking each spec and generating "cookbook" code.  This code is as follows:

    1) CHNNLDEF.H declares a class for every channel specified.  Each class
       declares a pure-virtual member function.  This approach lets C++'s
       polymorphism route channel messages to the appropriate objects.
       
    2) REGISTER.H declares the class Register and a global object, oRegister.
       All client messages are routed thru object oRegister.  For each
       channel there are four member functions:
       
            Connect, Disconnect, ChannelStatus, Execute<channel name>
            
       Connect and Disconnect are used by servers to control message
       routing to themselves.  Execute<> is used by a client to forward
       a message.  Anyone can use ChannelStatus -- examples are checking whether
       a connect or disconnect was successful or checking whether a channel has
       anyone connected.
       
       Register uses function overloading to map from a channel class to
       the corresponding channel list.  This is done for Connect, Disconnect,
       ChannelStatus, and Execute<>.
       
       There is a separate ChannelList object for each channel.  This is done for
       future enhancement when templates are supported.  Then, channel list pointers
       can refer to channel classes rather than being "void" pointers.
       
    3) REGISTER.CPP defines object oRegister and it's member functions.
    
    4) APP.CPP contains code templates.  It is available to assist programmers in
       writing code for clients and servers.


When writing code for a client or server, include file CHNNLDEF.H Classes that 
define objects servers must be derived from the corresponding register 
channel's class.  If an object receives data from more than one channel, then 
use multiple inheritance. 

Build your application by including module REGISTER.CPP in your project. 

Review the example program provided to get a better understanding about the use
of the Register Wizard.