| Allegro CL version 6.2 Object described on page has changed in 6.2 |
The default value of the topics argument to
open-server,
which determines the DDE topic names that DDE clients may specify to
connect with DDE servers running in Lisp. The initial value is the
list (nil :system :eval)
, meaning that the client
should specify the topic as one of the strings "nil", "system", or
"eval".
The default value :system
follows a DDE convention
where a DDE client can send a request with the "System" topic and the
"sysitems" item to find out what items are available under the
standard "System" topic, or with the "topics" item to find out what
other topics are available. A built-in answer-request method will reply to
these requests, and return the sysitems or service-topics for the Lisp
process that the server is running in.
The default value :eval
provides some built-in
behavior unique to an Allegro DDE server. If sent by a client in a
request with the name of a Lisp variable as the item, a built-in
answer-request
method returns the value of the variable (as a string). If the item
is "command-result", a built-in answer-request method returns the
value that was returned by the most recent command that the client
asked this Lisp server to perform (see execute-command). (When Lisp is the
client, it sends a command by calling send-command.) When the item is
"help", a string that explains these points is returned.
The default value nil
accepts a topic of
"nil" and passes the symbol nil
to
overridable DDE server generic functions such as answer-request and execute-command, but the
default methods for topic nil
do nothing.
Compatibility note: Starting with release 6.2, this variable is no longer automatically modified to match the service topics that were most recently passed to open-server. You may still modify the value of this variable to change the global default for service topics, but to retrieve the service topics that are actually being used by a particular Lisp process, you should call the function service-topics instead.
See cg-dde.htm for information about DDE support in Common Graphics.
Copyright (c) 1998-2002, Franz Inc. Oakland, CA., USA. All rights reserved.
Documentation for Allegro CL version 6.2. The object described on this page has been modified in the 6.2 release; see the Release Notes.
Created 2002.2.26.
| Allegro CL version 6.2 Object described on page has changed in 6.2 |