OpenMC/docs/source/devguide/user-input.rst
2018-08-02 10:49:40 -05:00

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.. _devguide_user_input:
=========================
Making User Input Changes
=========================
Users are encouraged to use OpenMC's :ref:`pythonapi` to build XML files that
the OpenMC solver then reads during the initialization phase. Thus, to modify,
add, or remove user input options, changes must be made both within the Python
API and the Fortran source that reads XML files produced by the Python API. The
following steps should be followed to make changes to user input:
1. Determine the Python class you need to change. For example, if you are adding
a new setting, you probably want to change the :class:`openmc.Settings`
class. If you are adding a new surface type, you would need to create a
subclass of :class:`openmc.Surface`.
2. To add a new option, the class will need a `property attribute`_. For
example, if you wanted to add a "fast_mode" setting, you would need two
methods that look like:
.. code-block:: python
@property
def fast_mode(self):
...
@fast_mode.setter
def fast_mode(self, fast_mode):
...
3. Make sure that when an instance of the class is exported to XML (usually
through a ``export_to_xml()`` or ``to_xml_element()`` method), a new element
is written to the appropriate file. OpenMC uses the
:mod:`xml.etree.ElementTree` API, so refer to the documentation of that
module for guidance on creating elements/attributes.
4. Make sure that your input can be categorized as one of the datatypes from
`XML Schema Part 2`_ and that parsing of the data appropriately reflects
this. For example, for a boolean_ value, true can be represented either by
"true" or by "1".
5. Now that you're done with the Python side, you need to make modifications to
the Fortran codebase. Make appropriate changes in the `input_xml module`_ to
read your new user input. You should use procedures and types defined by the
`xml_interface module`_.
6. If you've made changes in the geometry or materials, make sure they are
written out to the statepoint or summary files and that the
:class:`openmc.StatePoint` and :class:`openmc.Summary` classes read them in.
7. Finally, a set of `RELAX NG`_ schemas exists that enables validation of input
files. You should modify the RELAX NG schema for the file you changed. The
easiest way to do this is to change the `compact syntax`_ file
(e.g. ``src/relaxng/geometry.rnc``) and then convert it to regular XML syntax
using trang_::
trang geometry.rnc geometry.rng
For most user input additions and changes, it is simple enough to follow a
"monkey see, monkey do" approach. When in doubt, contact your nearest OpenMC
developer or send a message to the `developers mailing list`_.
.. _property attribute: https://docs.python.org/3.6/library/functions.html#property
.. _XML Schema Part 2: http://www.w3.org/TR/xmlschema-2/
.. _boolean: http://www.w3.org/TR/xmlschema-2/#boolean
.. _xml_interface module: https://github.com/openmc-dev/openmc/blob/develop/src/xml_interface.F90
.. _input_xml module: https://github.com/openmc-dev/openmc/blob/develop/src/input_xml.F90
.. _RELAX NG: http://relaxng.org/
.. _compact syntax: http://relaxng.org/compact-tutorial-20030326.html
.. _trang: http://www.thaiopensource.com/relaxng/trang.html
.. _developers mailing list: https://groups.google.com/forum/?fromgroups=#!forum/openmc-dev