def get_session_evaluation(session):
evaluation = _evaluations.get(session.session_key)
if evaluation is None:
definitions = Definitions(add_builtin=True)
# We set the formatter to "unformatted" so that we can use
# our own custom formatter that understand better how to format
# in the context of mathics-django.
# Previously, one specific format, like "xml" had to fit all.
evaluation = Evaluation(definitions,
format="unformatted",
output=WebOutput())
_evaluations[session.session_key] = evaluation
evaluation.format_output = lambda expr, format: format_output(
evaluation, expr, format)
autoload_files(definitions, ROOT_DIR, "autoload")
return evaluation
