Re: Proposal: using pkg-config for foreign dependencies in .egg-files

[felix . winkelmann]

>
> How about having something like `custom-config', which can be mapped
> to a program that produces a list that can be read into the egg
> specification tree?
>
> Reusing your example:
>
> ```
> ((synopsis "ZStandard bindings")
>  (author "Kristian Lein-Mathisen")
>  (category data)
>  (license "BSD")
>  (dependencies)
>  (test-dependencies test)
>  (components
>    (extension zstd-loq-level
>               (source "zstd-module.scm")
>               (source-dependencies "zstd.scm")
>               (csc-options
>                 (custom-config "custom-config.scm"))) ;; <- custom config 
> program
>              (extension zstd-nicer-api
>              (source "zstd-nicer-api.scm"))
>              (program "zcompress")))
> ```
>
> `custom-config.scm' would be a program that writes a list of options
> that would be used as `csc-options`.
>
> With that, we are more flexible and future-proof regarding the needs
> to adapt to different configuration mechanisms.  That also keeps the
> core free of dependencies and assumptions about external configuration
> tools.

I like this. So the custom config code would be a Scheme script, right?
We might want to support this regardless of how we proceed with
pkg-config. What I like about the pkg-config thing is that we have a
canonical way of specifying third-party packages, but on the other
hand every pseudo "standard" gets replaced at some stage by something
else.

The lack of declarativity is unfortunate, but we already have the ultime
loophole with custom-build (which includes the functionality of
custom-config but is of course more involved).


felix