On Tue, 09 Apr 2013 19:33:20 +0600, mark florisson
<markflorisso...@gmail.com> wrote:
On 9 April 2013 14:24, Stefan Behnel <stefan...@behnel.de> wrote:
mark florisson, 09.04.2013 15:13:
> On 9 April 2013 14:11, Stefan Behnel wrote:
>> Nathaniel Smith, 09.04.2013 15:00:
>>> On 9 Apr 2013 13:50, "Stefan Behnel" wrote:
>>>> There's also the problem of dependency hell and getting rid of old
>>>> modules
>>>> once they are no longer used on the user side. And also, how to get
them
>>>> there in the first place. Having one package overwrite the files of
>>>> another during its installation is just asking for trouble.
>>>
>>> The system I described does not involve the addition of any new
files
to
>>> any package.
>>
>> I take it then that you were envisaging a separate "cython-runtime"
package
>> on PyPI that Cython compiled modules would have to depend on?
>>
>> As long as people install their stuff using pip, that could work for
them
>> mostly ok, although with the regrettable Cython user impact of
having to
>> set that dependency for their packages in the first place.
>>
>> If people want to install stuff manually, dependency hell gets close.
>>
>> Or did you see any other ways of getting these things installed
>> automatically, with a smaller user impact?
>
> For reference, here's a CEP about this written last year:
> http://wiki.cython.org/enhancements/libcython
Ok, but that CEP excludes the rather vital problem of distribution and
installation. I also fail to see a reference to the problem of how
multiple
modules will interact that use different Cython runtime versions.
That's a
substantially bigger problem once symbols start becoming externally
visible.
Stefan
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I didn't say it was complete :) But the way I see it is basically what
Nathaniel said, i.e. Cython modules dependent on the runtime import it at
import time. It simply imports 'cython.runtime<xxx>', which has been made
available by the first module to initialize the runtime (compiled with
--include-runtime), or otherwise must be present on the filesystem. So
user
packages can depend on a cython-runtime-x.y package (where each x.y is a
different package), so pip will install all the runtime versions users
need
(or maybe we can otherwise improve upon this scheme).
Extra dependency may not matter much for scientific code,
but there are other users of Cython: library bindings, speedups
for general purpose modules etc. Another (versioned!) binary dependency
will become a liability to them.
If memoryviews rely on autogenerated (module-specific) code,
how is common runtime supposed to help?
The bulk of Cython utility code is also either inline or module-specific.
One alternative for code reuse in large Cython projects
could be packaging multiple modules into one shared library.
Best regards,
Nikita Nemkin
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