Re: ASDF, readtables and with-operation

Hi Richard,

Thanks for the thoughtful explanation and the code. I think that my  
readtable issues ended up being a "red herring" and I was definitely  
throwing thoughtless code at it in the hopes of making it just go  
away! <smile>

thanks again,

On Jan 17, 2007, at 3:26 PM, Richard M Kreuter wrote:

> The following message is a courtesy copy of an article
> that has been posted to gmane.lisp.cclan.general as well.
>
> Gary King <[email protected]> writes:
>
>> I'm working with code that plays some tricks on the readtable.
>> Occasionally, this causes compilation of other systems to fail
>> because the altered readtable generally mucks things up. At the risk
>> of violating "you aren't going to need it", here is a suggested
>> patch.
>
> Assuming you haven't hosed the readtable too badly, can't you say
>
> (let ((*readtable* (copy-readtable nil)))
>   (asdf:oos ... ...))
>
> ?
>
> If someone wants to use a non-standard readtable by default when
> operating on asdf systems, this proposal would prevent that.  (Support
> for doing strange things with the readtable is limited in most
> implementations, but I don't think that asdf ought to constrain things
> this way.)
>
> Additionally, note that OPERATE is /not/ invoked recursively to
> perform dependent operations on dependent systems.  So the
> START-OPERATION and STOP-OPERATION functions you propose will only get
> called for an operation/system pair when these are explicitly
> OPERATE'd on, but not when the operation is performed on the system as
> part because of operation or system dependencies.
>
> That said, there are a couple systems in the wild from which you can
> generalize a technique for simulating auxiliary methods to be run
> before and around whole systems (either for side-effects, or for
> bindings).  The recipe is to specialize the auxiliary method on the
> subclass of cl-source-file of which the system's files are instances,
> and to stash whatever information you need in the system itself.  (To
> make this the site-wide default, unforuntately, requires either
> editing all your .asds, editing asdf.lisp, or using a MOP to add
> superclasses to asdf's standard classes.)
>
> Here, I think, is one way to simulate rebinding the readtable around
> system compilation and loading.  It adds a readtable slot to system
> instances, and rebinds readtable to the system's readtable during
> compilation and loading of the system's files.  (I've not tested this
> code, but I've got similar code to rearrange the package namespace
> around operations):
>
> --
> (defpackage :not-asdf
>   (:use :cl :asdf))
>
> (in-package :not-asdf)
>
> (defclass readtable-rebinding-mixin () ())
>
> (defclass readtable-holder ()
>   ((readtable :initarg :readtable :accessor readtable-of)))
>
> (defun component-system (component)
>   (if (typep component 'system)
>       component
>       (component-system (component-parent component))))
>
> (defmethod perform :around ((op compile-op) (comp readtable- 
> rebinding-mixin))
>   (let* ((component-system (component-system comp))
>          (*readtable* (if (and (typep component-system 'readtable- 
> holder)
>                                (slot-boundp component-system  
> 'readtable))
>                           (readtable-of component-system)
>                           *readtable*)))
>     (call-next-method)))
>
> (defmethod perform :around ((op load-op) (comp readtable-rebinding- 
> mixin))
>   (let* ((component-system (component-system comp))
>          (*readtable* (if (and (typep component-system 'readtable- 
> aware-system)
>                                (slot-boundp component-system  
> 'readtable))
>                           (readtable-of component-system)
>                           *readtable*)))
>     (call-next-method)))
>
> ;; If you're not interested in redefining asdf:system and
> ;; asdf:cl-source-file but want this behavior to be the site-wide
> ;; default, compose all the extension classes you like into named
> ;; classes, and then change your systems' .asd file to use those
> ;; classes, e.g.,
>
> (defclass local-cl-source-file
>      (readtable-rebinding-mixin ... cl-source-file)
>   ())
>
> (defclass local-system (readtable-holder ... system)
>   ())
>
> (defsystem <system-name>
>   :class local-system
>   :default-component-class local-cl-source-file
>   ...)
> --
>
> Hope that helps,
> RmK

--
Gary Warren King, metabang.com
Cell: (413) 885 9127
Fax: (206) 338-4052
gwkkwg on Skype * garethsan on AIM





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