[IPOL discuss] ipol_demo, matplotlib and other modules [ Re: Noise estimation ready in dev. server ]

[Nicolas Limare]

> It is using the matplotlib library to draw the noise level figure right
> now, although after discussing it with Nicolas Limare, it seem that this
> library is going to be discarded for IPOL because its API is not stable.

Here is a partial copy of my previous mail to Miguel about it:

8<----------8<----------8<----------8<----------8<----------8<----------

> I don't see any reason to avoid installing it in the production
> server, because we can draw very complete figures with it
> easily.

Yes, we can draw nice figures easily, this is a reason for using
it. My reason for *not* using it is, as usual, instability of the API
over time. We already have problems with PIL (one version can read
interlaced PNG, the other can't), and with the python zip and tar
modules (some useful options are only available in python >2.6, which
was not in Debian until 3 months ago). If we allow the demos to use
matplotlib, there is a high probability that some demos will be broken
at the next server upgrade. Who will fix these demos?

8<----------8<----------8<----------8<----------8<----------8<----------

I didn't study the matplotlib API stability. What I say is that we can
not use another python module for the only reason that it is
useful (or convenoient or nice). The only dependencies for the moment
are cherrypy, PIL, tar/zip and sqlite modules, and there already are
some compatibility problems, as explained before. I think we should
only consider additional dependencies if they are useful and can not
be replaced by internal tools and we have some reason to think they
will be available without API break for a *long* time.

No one wants to investigate the 200 demos we may have in 2015, some
written by people who went to other places, some badly documented or
badly written, in order to update the server without breaking the
service. Or if you want, please volunteer, but I certainly don't.

-- 
Nicolas LIMARE - CMLA - ENS Cachan    http://www.cmla.ens-cachan.fr/~limare/
IPOL - image processing on line                          http://www.ipol.im/
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