Re: on the loading of preference files

Here is the current diff for adding preference loading to ASDF. The  
diff does the following:

* defines and exports two generic functions: load-preferences and  
preference-file-for-system/operation. Both of these
take two parameters: an operation and a component.
* Adds a call to load-preferences to the perform :after for  
operation / component.
* defines a new class 'basic-load-op' from which both load-op and  
load-source-op inherit
* defines a method on load-preferences that dispatches on basic-load- 
op and system

this is setup so that preferences are to be found in a file names  
<system-name>.lisp in the directory ~/.asdf. Of course, one could  
change that by writing another preference-file-for-system/operation.

comments welcome...

thanks,


> Index: asdf.lisp
> ===================================================================
> RCS file: /cvsroot/cclan/asdf/asdf.lisp,v
> retrieving revision 1.99
> diff -u -w -u -r1.99 asdf.lisp
> --- asdf.lisp	16 Jun 2006 20:17:01 -0000	1.99
> +++ asdf.lisp	27 Jun 2006 12:01:49 -0000
> @@ -101,6 +101,8 @@
> 	   #:retry
> 	   #:accept                     ; restarts
> 	
> +           #:preference-file-for-system/operation
> +           #:load-preferences
> 	   )
>    (:use :cl))
> @@ -732,7 +734,8 @@
> (defmethod perform :after ((operation operation) (c component))
>    (setf (gethash (type-of operation) (component-operation-times c))
> -	(get-universal-time)))
> +	(get-universal-time))
> +  (load-preferences c operation))
> ;;; perform is required to check output-files to find out where to put
> ;;; its answers, in case it has been overridden for site policy
> @@ -773,7 +776,9 @@
> ;;; load-op
> -(defclass load-op (operation) ())
> +(defclass basic-load-op (operation) ())
> +
> +(defclass load-op (basic-load-op) ())
> (defmethod perform ((o load-op) (c cl-source-file))
>    (mapcar #'load (input-files o c)))
> @@ -792,7 +797,7 @@
> ;;; load-source-op
> -(defclass load-source-op (operation) ())
> +(defclass load-source-op (basic-load-op) ())
> (defmethod perform ((o load-source-op) (c cl-source-file))
>    (let ((source (component-pathname c)))
> @@ -827,6 +832,38 @@
> (defmethod perform ((operation test-op) (c component))
>    nil)
> +(defgeneric load-preferences (system operation)
> +  (:documentation "Called to load system preferences after  
> <perform operation system>. Typical uses are to set parameters that  
> don't exist until after the system has been loaded."))
> +
> +(defgeneric preference-file-for-system/operation (system operation)
> +  (:documentation "Returns the pathname of the preference file for  
> this system. Called by 'load-preferences to determine what file to  
> load."))
> +
> +(defmethod load-preferences ((s t) (operation t))
> +  ;; do nothing
> +  (values))
> +
> +(defmethod load-preferences ((s system) (operation basic-load-op))
> +  (let* ((*package* (find-package :common-lisp))
> +         (file (probe-file (preference-file-for-system/operation s  
> operation))))
> +    (when file
> +      (when *verbose-out*
> +	(format *verbose-out*
> +		"~&~@<; ~@;loading preferences for ~A/~(~A~) from ~A~@:>~%"
> +		(component-name s)
> +		(type-of operation) file))
> +      (load file))))
> +
> +(defmethod preference-file-for-system/operation ((system t)  
> (operation t))
> +  ;; cope with anything other than systems
> +  (preference-file-for-system/operation (find-system system t)  
> operation))
> +
> +(defmethod preference-file-for-system/operation ((s system)  
> (operation t))
> +  (merge-pathnames
> +   (make-pathname :name (component-name s)
> +                  :type "lisp"
> +                  :directory '(:relative ".asdf"))
> +   (truename (user-homedir-pathname))))
> +
> ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
> ;;; invoking operations
>


On Jun 20, 2006, at 10:45 AM, Christophe Rhodes wrote:


> Gary King <[email protected]> writes:
>
>
>>> +(defgeneric load-preferences (system)
>>> +  (:documentation "Called to load system preferences after
>>> <perform load-op system>. Typical uses are to set parameters that
>>> don't exist until after the system has been loaded."))
>>> +
>>> +(defgeneric preference-file-for-system (system)
>>> +  (:documentation "Returns the pathname of the preference file for
>>> this system. Called by 'load-preferences to determine what file to
>>> load."))
>>>
>
> I think that both of these should have an operation argument
> additionally.  It's not just after performing a load-op that a
> preferences file should be loaded -- consider a load-source operation,
> not to mention possible user-specified operations.
>
> Alternatively, if you believe that there's one and only one
> preference-file-loading operation, then it probably deserves to be an
> operation in and of itself.
>
> Cheers,
>
> Christophe
>


-- 
Gary Warren King
metabang.com
http://www.metabang.com/
(413) 210 7511
gwking on #lisp (occasionally)



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