.. _faq:

Frequently Asked Questions
==========================

TypeError: Unable to convert function return value to a Python type
-------------------------------------------------------------------

This is likely due to a missing PyEDDL import. Some ECVL functions return EDDL
types, whose Python bindings are in PyEDDL. To fix this problem, add (at
least) one of the following imports (even if you're not going to use it):

.. code-block:: python

    import pyeddl.eddl
    import pyeddl.tensor

Can I use PyEDDL 0.7.0 with PyECVL 0.3.0?
-----------------------------------------

PyEDDL 0.7.0 depends on EDDL 0.5.4a. PyECVL 0.3.0 depends on ECVL 0.2.1, which
fails to build its EDDL support module for EDDL 0.5.4a due to a change in the
EDDL CMake config file names since version 0.4.4.

However, there's a workaround to make it work. After installing EDDL 0.5.4a,
change to the installation directory for CMake config files (e.g.,
``/usr/local/lib/cmake/``) and create symlinks with the names expected by ECVL
0.2.1. Example::

    cd /usr/local/lib/cmake/eddl
    ln -s EDDLConfig.cmake eddlConfig.cmake
    ln -s EDDLConfigVersion.cmake eddlConfigVersion.cmake
    ln -s EDDLTargets-release.cmake eddlTargets-release.cmake
    ln -s EDDLTargets.cmake eddlTargets.cmake

This should allow you to build ECVL with EDDL support, after which you can
build PyEDDL and PyECVL.