Entry points

The (de-)serialization methods registered with fsc.hdf5-io are only available once the Python module defining them has been loaded. To avoid having to explicitly import all necessary modules before loading a module, fsc.hdf5-io defines two entry point groups:

Serialization: fsc.hdf5_io.save

When a Python object whose serialization is not defined is encountered, fsc.hdf5-io will load (if it exists) the entry point corresponding to the full name of the object’s class in the fsc.hdf5_io.save entrypoint. If there is no entry point for the exact Python name, it will also try its module name(s).

For example, if a scipy.sparse.csr.csr_matrix should be serialized, it will first check for an entry point named scipy.sparse.csr.csr_matrix in fsc.hdf5_io.save. If this entry point does not exist, it will try scipy.sparse.csr, scipy.sparse, and scipy, stopping at the first entry point that exists.

If you were to define serialization for all scipy.sparse objects in a module called scipy_helpers.sparse.hdf5_io, you could define the following entry point in the module setup.py (as an argument to the setup function):

    'fsc.hdf5_io.save': ['scipy.sparse = scipy_helpers.sparse.hdf5_io']

Deserialization: fsc.hdf5_io.load

The same principle applies for deserializing HDF5 objects, but the entry point names go by type_tag instead. For example, if you define your_module with type tags your_module.some_object and your_module.another_object, you have two choices:

If the top-level import of your_module loads all the submodules needed to deserialize both classes, the following configuration enables autoloading:

    'fsc.hdf5_io.load': ['your_module = your_module']

If instead they are in two separate submodules some_object_submodule and another_object_submodule that are not loaded when simply importing your_module, you need to define two entry points:

    'fsc.hdf5_io.load': [
        'your_module.some_object = your_module.some_object_submodule',
        'your_module.another_object = your_module.another_object_submodule',

As a real-world example, fsc.hdf5-io itself uses entry points to define the (de-)serialization of sympy objects, without always having to import sympy.