doc-rst: support *sphinx build themes*

  From: Markus Heiser <markus.heiser@darmarIT.de>

Load an additional configuration file into conf.py namespace.

The name of the configuration file is taken from the environment
SPHINX_CONF. The external configuration file extends (or overwrites) the
configuration values from the origin conf.py.  With this you are
able to maintain *build themes*.

E.g. to create your own nit-picking *build theme*, create a file
Documentation/conf_nitpick.py::

  nitpicky=True
  nitpick_ignore = [
      ("c:func", "clock_gettime"),
      ...
      ]

and run make with SPHINX_CONF environment::

  make SPHINX_CONF=conf_nitpick.py htmldocs

Signed-off-by: Markus Heiser <markus.heiser@darmarIT.de>
---
 Documentation/conf.py               |  9 +++++++++
 Documentation/sphinx/load_config.py | 25 +++++++++++++++++++++++++
 2 files changed, 34 insertions(+)
 create mode 100644 Documentation/sphinx/load_config.py
  

On Fri, 05 Aug 2016, Markus Heiser <markus.heiser@darmarit.de> wrote:
> From: Markus Heiser <markus.heiser@darmarIT.de>
>
> Load an additional configuration file into conf.py namespace.
>
> The name of the configuration file is taken from the environment
> SPHINX_CONF. The external configuration file extends (or overwrites) the
> configuration values from the origin conf.py.  With this you are
> able to maintain *build themes*.
>
> E.g. to create your own nit-picking *build theme*, create a file
> Documentation/conf_nitpick.py::
>
>   nitpicky=True
>   nitpick_ignore = [
>       ("c:func", "clock_gettime"),
>       ...
>       ]
>
> and run make with SPHINX_CONF environment::
>
>   make SPHINX_CONF=conf_nitpick.py htmldocs

I think I would try to accomplish this by using the -c option in
SPHINXOPTS, and loading the main config file from the "special case"
config file. I think it would be a more generic approach instead of a
specific framework of our own. *shrug*.

BR,
Jani.


>
> Signed-off-by: Markus Heiser <markus.heiser@darmarIT.de>
> ---
>  Documentation/conf.py               |  9 +++++++++
>  Documentation/sphinx/load_config.py | 25 +++++++++++++++++++++++++
>  2 files changed, 34 insertions(+)
>  create mode 100644 Documentation/sphinx/load_config.py
>
> diff --git a/Documentation/conf.py b/Documentation/conf.py
> index 96b7aa6..d502775 100644
> --- a/Documentation/conf.py
> +++ b/Documentation/conf.py
> @@ -20,6 +20,8 @@ import os
>  # documentation root, use os.path.abspath to make it absolute, like shown here.
>  sys.path.insert(0, os.path.abspath('sphinx'))
>  
> +from load_config import loadConfig
> +
>  # -- General configuration ------------------------------------------------
>  
>  # If your documentation needs a minimal Sphinx version, state it here.
> @@ -419,3 +421,10 @@ pdf_documents = [
>  # line arguments.
>  kerneldoc_bin = '../scripts/kernel-doc'
>  kerneldoc_srctree = '..'
> +
> +
> +# ------------------------------------------------------------------------------
> +# Since loadConfig overwrites settings from the global namespace, it has to be
> +# the last statement in the conf.py file
> +# ------------------------------------------------------------------------------
> +loadConfig(globals())
> diff --git a/Documentation/sphinx/load_config.py b/Documentation/sphinx/load_config.py
> new file mode 100644
> index 0000000..44bdd22
> --- /dev/null
> +++ b/Documentation/sphinx/load_config.py
> @@ -0,0 +1,25 @@
> +# -*- coding: utf-8; mode: python -*-
> +# pylint: disable=R0903, C0330, R0914, R0912, E0401
> +
> +import os
> +from sphinx.util.pycompat import execfile_
> +
> +# ------------------------------------------------------------------------------
> +def loadConfig(namespace):
> +# ------------------------------------------------------------------------------
> +
> +    u"""Load an additional configuration file into *namespace*.
> +
> +    The name of the configuration file is taken from the environment
> +    ``SPHINX_CONF``. The external configuration file extends (or overwrites) the
> +    configuration values from the origin ``conf.py``.  With this you are able to
> +    maintain *build themes*.  """
> +
> +    config_file = os.environ.get("SPHINX_CONF", None)
> +    if config_file is not None and os.path.exists(config_file):
> +        config_file = os.path.abspath(config_file)
> +        config = namespace.copy()
> +        config['__file__'] = config_file
> +        execfile_(config_file, config)
> +        del config['__file__']
> +        namespace.update(config)