[Qgis-developer] Plugin Dependencies

[Hugo Mercier]

Hi Alessandro,

On 26/10/2015 17:50, Alessandro Pasotti wrote:

> Hello Hugo,
> 
> IMHO using  setuptools and pip it's a good idea, it does support
> download and install from several protocols (git included) out of the
> box, it also support dependencies and keywords licence tags, I'm not
> sure that it can support custom tags too, but it it's not so important.
> 
> I guess that most of the times, a plugin would not even need to be
> hosted by us on plugins.qgis.org <http://plugins.qgis.org> but it could
> just be a git(hub) URI (with a big red warning to the the users that
> they are installing software from an external repository  etc. etc.).

Exactly. That are interesting features.

> 
> I'm not sure about the support on other platforms, luckily (for me) I'm
> deeply ignorant about other OSes but it seems that windows users often
> have a lot of problems with installing and running python code: would
> pip/setuptools make things easier for them?

Actually, this is the main concern I have with the current system: most
of the Windows users get their python environment through the QGIS
installer or osgeo4w. And if a plugin needs another dependency, it has
to be installed by other means.
Pip does exist for Windows and OSX and could act as a package manager
(where Linux users are usually happy with their distro package manager)

> 
> I don't understand completely what do you mean with the other points
> (virtualenvs and binary parts) can you elaborate?

These are just ideas for now :) I don't have a strong experience with
these tools, so it would have to be confirmed.
But the idea is that if QGIS plugins are built with setuptools / pip,
then you can setup different virtualenvs with different sets of plugins
available in them. That may be interesting when dealing with different
user profiles or during development.

About binary parts: setuptools allows to insert compilation directives
if a module depends on C(++) parts. I don't know if this feature could
allow plugins with compiled parts ... the idea would be to include C(++)
sources with the plugin and have a standard way of compiling it, so that
it could be compiled by trusted sources on main platforms ... or by the
user if a standard compilation environment is present.