Re: [PATCH] gnu: Add Cython

[Eric Bavier]

Federico Beffa writes:

> In preparing this package I've found that the python-build-system (not
> sure about the others) defines the environment variable HOME as
> "/homeless-shelter". However, that directory does not exist in the
> build chroot. This is a problem for cython, because it wants to access
> $HOME/.cython. Wouldn't it be better to point HOME to an existing
> directory (created in the chroot) with suitable permissions?

It's not a common need when building packages.  There are a few other
packages that need an existing, writable $HOME when building or testing.

> I'm a little bit unsure about the name of the package. I've not
> prefixed it with "python[2]-" as the program extends the Python
> language and can work with both (2 and 3) Python version series.
> However, the package installs files in
> ".../lib/python${version}/site-packages/...". The naming is in-line
> with Debian naming.

What you did seems reasonable to me.

> From b9e7cdb367518547be3d8bc535828a0d1f1ac96e Mon Sep 17 00:00:00 2001
> From: Federico Beffa <address@hidden>
> Date: Mon, 20 Oct 2014 19:52:45 +0200
> Subject: [PATCH] gnu: Add Cython
> 
> * gnu/packages/python.scm(cython,cython2): New variables

Period "." at the end.
 
> ---
>  gnu/packages/python.scm | 50
>  +++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 50 insertions(+)
> 
> diff --git a/gnu/packages/python.scm b/gnu/packages/python.scm
> index 897e248..f8503c3 100644
> --- a/gnu/packages/python.scm
> +++ b/gnu/packages/python.scm
> @@ -37,6 +37,7 @@
>    #:use-module (gnu packages pkg-config)
>    #:use-module (gnu packages databases)
>    #:use-module (gnu packages zip)
> +  #:use-module (gnu packages gcc)

I don't see what prompts this new module.  Leftover from development?

>  (define-public python2-sphinx
>    (package-with-python2 python-sphinx))
> +
> +(define-public cython
> +  (package
> +    (name "cython")
> +    (version "0.21.1")
> +    (source
> +     (origin
> +       (method url-fetch)
> +       (uri (string-append
> +             "http://cython.org/release/Cython-";
> +             version ".tar.gz"))

The style in the rest of the file would dictate that the uri begin on
the same line as string-append.

> +       (sha256
> +        (base32
> +         "0ddz2l2dvcy5hdkxx4xlfiwpccvwia7ixgcy4h0pdv46a4i4vxj3"))))
> +    (build-system python-build-system)
> +    (inputs
> +     `(("python" ,python))) ; otherwise ld doesn't find libpython3.3m.so
> +    (arguments
> +     `(#:phases
> +       (alist-replace
> +        'build
> +        (lambda* (#:key outputs inputs 
> +                  #:allow-other-keys #:rest args)
> +          (let ((build (assoc-ref %standard-phases 'build)))
> +            (setenv "HOME" "/tmp") ; some tests require access to 
> "$HOME/.cython"
> +            (apply build args)))

If $HOME is only required for tests only, please make the setenv a
separate phase that comes just before the check phase.  See
e.g. duplicity or rdup in gnu/packages/backup.scm, or the definition of
python-2 itself.  We try to avoid "wrapping" phases with (apply <phase>
args).

> +        (alist-replace
> +         'check
> +         (lambda _ (zero? 
> +                    (system* "python" 
> +                             "runtests.py" 
> +                             "-vv")))

Nitpicky: the lambda could probably go on a single line
(e.g. python-parse or python-enum34).

> +         %standard-phases))))
> +    (home-page "http://cython.org/";)
> +    (synopsis "C extensions for Python")
> +    (description "Cython is an optimising static compiler for both the Python
> +programming language and the extended Cython programming language.  It makes
> +writing C extensions for Python as easy as Python itself.")
> +    (license asl2.0)))
> +
> +(define-public cython2
> +  (package 
> +    (inherit cython)
> +    (name "cython2")
> +    (build-system python-build-system)
> +    (inputs
> +     `(("python-2" ,python-2)))
> +    (arguments
> +     `(#:python ,python-2 ,@(package-arguments cython)))))

Does package-with-python2 not work here?  You might be able to do::

(define-public cython2
  (package (inherit (package-with-python2 cython))
    (name "cython2")))

-- 
Eric Bavier