Re: [go-build-system] How to access properties or keys of a package on the build side?

[Ricardo Wurmus]

Leo Famulari <address@hidden> writes:

> On Mon, Aug 28, 2017 at 10:32:41PM +0200, Ricardo Wurmus wrote:
>>
>> Ricardo Wurmus <address@hidden> writes:
>>
>> > You could also access the arguments of another package with
>> > “package-arguments”.  Using the “properties” field isn’t pretty because
>> > it is a free form alist.
>> >
>> > You can use “find-tail” to jump to the keyword in “arguments” and then
>> > pick the following value.
>>
>> Here an example:
>>
>> --8<---------------cut here---------------start------------->8---
>> (define (assoc-args-ref pkg key)
>>   "Return the value associated with KEY in the arguments of package PKG,
>> or #F if there is no such key."
>>   (let ((ref (find-tail (cut eq? <> key)
>>                         (package-arguments pkg))))
>>     (and=> ref second)))
>>
>> (assoc-args-ref golang-github-com-audriusbutkevicius-go-nat-pmp
>>                 #:import-path)
>>
>> => "github.com/AudriusButkevicius/go-nat-pmp"
>> --8<---------------cut here---------------end--------------->8---
>
> I didn't get very far in this direction before deciding to try another
> technique. But wouldn't this not work on the build side, since (guix
> packages) is not available there?

It would work because you’re executing this on the host side and paste
the result into the S-expression that is the value of the “arguments”
field.

--
Ricardo

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