Hi Ludo',
Ludovic Courtès <[email protected]> writes:
> Something just came to mind: the object cache. The cache is keyed by
> object + system + target + grafts?; if there’s anything that influences
> what the object lowers to, changes are the object->derivation mapping is
> already cached and that other thing will be ignored.
Oh that's true, this is an additional problem. Would it make sense to
add the parameters passed to `with-parameters' to the keys used in
`mcached'? Then the parameters would have to be passed around quite a
bit however...
Alternatively, would it be possible to query the fluids with
`current-dynamic-state' instead and use that for the keys in `mcached'?
I don't see any way to inspect a dynamic state though.
> That’s a problem generally speaking with using ‘with-parameters’ with
> parameters other than ‘%current-system’, ‘%current-target-system’, and
> ‘%graft?’.
I think `with-parameters' only works for `%current-system' and
`%current-target-system', not for `%graft?': When setting `%graft?' to
#f in the second `with-parameters' wrapping in
`graft-derivation/shallow', it still evaluates to the same derivation as
with `%graft?' set to #t.
> I wonder if it’s the only thing at play here though.
No, attached is a simplified example without a package using a record
(named <test>) with a (thunked) field. Removing the `mcached' calls in
(guix gexp) results in the same derivation. I think this is because
`lower-object' returns a monadic procedure, which does not keep the
fluids set by `with-parameters', so when the (thunked) field is
evaluated, the parameter has changed.
Maybe it would be good to pass the parameters from the gexp compiler of
<parameterized> to `lower-object' as additional argument and use
`with-fluids*' there (just before `lower' is called)? This worked for
the <test> record defined in the attachment, but not for a package, I
guess because of the expander? I'm not sure how to pass the parameters
in that case though.
Best,
David
(use-modules
(guix gexp)
(guix monads)
(guix records)
(guix store)
(guix utils))
(define-record-type* <test>
test make-test
test?
this-test
(field test-field (thunked)))
(define* (test->derivation test)
(with-monad %store-monad
(gexp->derivation
"test"
#~(let ((port (open-file #$output "w")))
(display
(string-append #$(test-field test) "\n") port)
(close-port port)))))
(define-gexp-compiler (test-compiler (test <test>) system target)
(test->derivation test))
(define %param
(make-parameter "A"))
(define testvalue
(test
(field (%param))))
(%param "B")
(define testvalue2
(with-parameters
((%param "C"))
testvalue))
(%param "D")
testvalue2
