new module directive? [was: Three real-life questions]

new module directive? [was: Three real-life questions]

[Andreas Rottmann]

Andy Wingo <wingo@pobox.com> writes:

> Hi Michael,
>
> On Tue, 2004-04-06 at 13:01, Michael Burschik wrote:
>> 1. How should one export, or re-export modified generic functions?
>>  Using :export seems to work as expected, although guile complains
>>  about the use of deprecated features. Using :re-export gets rid of the
>>  complaints, but does not seem to be documented in the guile manual. So
>>  what is the correct way to handle generic functions in modules?
>
> If a module that you use supplies a binding, and you want that binding
> to be available for users of your module, you must re-export it. This
> applies to generics as well as other bindings. Lack of documentation on
> this is a bug, though!
>
The hairy thing is when you want to override (extend) a non-generic
with a generic. #:re-export won't work in this case and #:export gives
a warning. Example code:

;; export-test.scm

(define-module (export-test)
  #:use-module (oop goops)
  #:export (quit))

(define quit (ensure-generic quit))

(define-class <mainloop>)

(define-method (quit (loop <mainloop>))
  ;; some code here
  loop)

Then, the extended quit works as expected:

ivanova:~/tmp/test% guile
guile> (use-modules (export-test) (oop goops))
Using `export' to re-export imported bindings is deprecated.  Use `re-export' instead.
(You just re-exported `quit' from `(export-test)'.)
guile> (quit (make <mainloop>))
#<<mainloop> 80891a0>
guile> (quit 66)
ivanova:~/tmp/test% echo $?
66

I'd really like to see an #:override or somesuch module option that
doesn't warn in this case...

Andy
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Re: new module directive? [was: Three real-life questions]

[Michael Burschik]

Andreas Rottmann says:

> The hairy thing is when you want to override (extend) a non-generic
> with a generic. #:re-export won't work in this case and #:export gives
> a warning.

This is pretty nasty, especially since #:re-export gives no indication of
not working, and I did not, in fact, notice that it does not. I extended
equal? with a generic and it seemed to work as expected when I used
#:re-export. Was this simply a coincidence, or is equal? generic anyway?

Regards

Michael Burschik



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Re: new module directive?

[Andreas Rottmann]

"Michael Burschik" <Burschik@lotto-berlin.de> writes:

> Andreas Rottmann says:
>
>> The hairy thing is when you want to override (extend) a non-generic
>> with a generic. #:re-export won't work in this case and #:export gives
>> a warning.
>
> This is pretty nasty, especially since #:re-export gives no indication of
> not working, and I did not, in fact, notice that it does not. I extended
> equal? with a generic and it seemed to work as expected when I used
> #:re-export. Was this simply a coincidence, or is equal? generic anyway?
>
As soon GOOPS is loaded, equal? is changed to a
"primitive-generic". IMHO, it would be nice if that would happen for
every procedure...

guile> equal?
#<primitive-procedure equal?>
guile> (use-modules (oop goops))
guile> equal?
#<primitive-generic equal?>

Andy
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