| Allegro CL version 9.0 Unrevised from 8.2 to 9.0. 8.2 version |
Arguments: home-location class-name import-name &optional propagate
This function defines a mapping from the string to the local class
named by class-name. It returns the class name.
This class must be a sub-class of rpc-remote-ref
or an error is
signaled. home-location must be an instance of
rpc-port
or of rpc-port-server
(its presence
allows the generic function to behave differently on the two classes).
When a remote reference to a class arrives at a port, the class is
identified by a string. This string is compared (with string-equal) to the
import-name strings defined by this function. If a match occurs, an
instance of the corresponding class-name is created instead of a
direct instance of rpc-remote-ref
.
To avoid ambiguities or conflicts caused by package and case differences between remote images, an application can use export-remote-symbol in the sender to define unique class identifier strings and import-remote-class in the receiver to interpret these unique strings.
This method updates the table stored in the rpc-port-server
instance. The table is
copied to any new rpc-port
instances created from the server.
If the propagate argument is non-nil, then all
active ports created from this server are updated as well.
This method updates the table in the specified rpc-port
instance.
The propagate argument is ignored.
Subclasses of rpc-remote-ref
must not be instantiated by
application programs. Any instance of rpc-remote-ref
created by a direct call to
make-instance
will cause serious errors in the application.
Instances of rpc-remote-ref
(and any subclasses) are
only created when a remote reference arrives at an rpc-port
, or when an
application needs to create an explicit wrapper with a call to rref or rpc-ref.
Image A calls image B with:
(rcall 'foo (make-instance 'bar))
In image B, the function foo gets an instance of rpc-remote-ref
as its one
argument x. (rr-type x)
returns the string "bar". Image B can only obtain additional
information about the object x by calling back to
A.
But image B could also do as follows:
(defclass far-bar (rpc-remote-ref) ()) (import-remote-class port-to-a 'far-bar "bar")
At this point, the function foo gets an instance of
far-bar
as an argument. This is a local class that
may be used to dispatch appropriate methods in image B.
For example, in image A, the class bar
may have a
slot accessed with accessor count. One way to call this accessor from
image B is to use
(rcall 'count x)
But since import-remote-class caused a local class to be instantiated, we can define in image B
(defmethod count ((x far-bar)) (rcall 'count x))
and access the slot with (count x)
.
See export-remote-symbol for what to do if the class name represented simply as the symbol name might cause ambiguity.
See also rpc.htm for general information on the Remote Procedure Call utility in Allegro CL.
Copyright (c) 1998-2019, Franz Inc. Oakland, CA., USA. All rights reserved.
This page was not revised from the 8.2 page.
Created 2012.5.30.
| Allegro CL version 9.0 Unrevised from 8.2 to 9.0. 8.2 version |