[DebianGIS] Re: thuban strict wxPython version check?

[Bernhard Herzog <bh@intevation.de>]

Paul Wise <pabs3@bonedaddy.net> writes:

> I'm wondering what the following check from Thuban/version.py is for? Is
> the wxWidgets ABI really so fragile that wxProj breaks on new minor
> 2.6.X versions or new 2.4.X versions? Surely using the soname to do
> version checks with the normal shared library support is enough?

The symptom people often see when using Thuban with a different
wxWidgets version -- even when it's only a different minor version -- is
that it segfaults as soon as it tries to actually render a map on the
screen.  In the past there were enough problem reports from users about
this for us to put in the version check so that users would at least get
a meaningful error message instead of just a segfault.

The reason for the crashes is that wxproj accesses wxPython objects at
the C++-level to extract the corresponding wxWidgets object so that it
can call wxWidgets methods directly.  That way, Thuban can render data
read from e.g. a shapefile without having to funnel the data through
Python which improves rendering speed considerably.

Unfortunately, this means that the wxWidgets object used by wxproj has
been created by the wxWidgets library wxPython is linked with and that
may be different from the one wxproj is linked with.  The libraries may
differ in the layout of the classes and/or virtual tables depending on
the version and perhaps compile time options.

  Bernhard

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