Re: defsystem optionally loaded subsystem

> From: "Liam M. Healy" <[email protected]>
> Reply-to: Liam Healy <[email protected]>
> Sender: [email protected]
> X-Original-Date: Mon, 25 Nov 2002 09:33:12 -0500
> Date: Mon, 25 Nov 2002 09:33:12 -0500
> X-UIDL: -0P!!`4%"!,4T"!0,&#!
> 
> In one of my systems, I have a few files whose definitions are
> infrequently used and that are time-consuming to load.  I would like
> to make them optionally load under defsystem-3.x:  they would compile
> with the rest of the system, but would only be loaded with an explicit
> command.  I do not want to make them a separate system because I want
> to keep them associated with this system.  Is there a way to do this
> easily in the defsystem structure?

The way I do it is the group these files into a separate :module with
no (or only few) dependencies.

This way you get compilation and loading of these files only at
specific times.  E.g.

	 (mk:defsystem "FOO"
              :components ("base"
                           (:module "load-sparingly"
                                    :source-pathname "where/they/are/"
                                    :components ("f1" "f2"))
                           (:file "x"
                                  :depends-on ("base" "load-sparingly"))))

... I think you get the idea.

MK4 has extended dependencies (following the ideas of KMP's paper and
ASDF) with a somewhat clumsy syntax.  You will be able to say


	 (mk4:defsystem "FOO"
              :components ("base"
                           (:module "load-sparingly"
                                    :source-pathname "where/they/are/"
                                    :components ("f1" "f2"))
                           (:file "x"
                                  :depends-on ("base"
                                               (:load "load-sparingly"))
					       )))

Meaning that file "x" will depend on "load-sparingly" only for the
:load operation.

Check out module `defsystem-4.x' to play around with it.  It is not
ready for prime time yet, but it is getting there.

> As a side point, I think the documentation is out of date
> src/defsystem-3.x/docs/defsystem.html refers to Mark Kantrowitz for
> bugs etc.

Thanks.  I will fix that.

Cheers


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