CondConfigParser 1.0.5

Python library for parsing configuration files with conditionals

Python library for parsing configuration files with conditionals

CondConfigParser is a Python library designed to help Python application developers to parse configuration files. Compared to well-known modules such as configparser and json, the main specificity of CondConfigParser is that it allows the end user to define conditions using boolean operators and specific sections in the configuration file that are only applied when the corresponding condition is fulfilled.

The configuration file format allows the end user to define variables of type boolean, string or list. These variables, in addition to external variables defined by the application, can be combined with Python-like syntax to define the conditions (called predicates) mentioned in the previous paragraph.

Lists in CondConfigParser may be nested at will. Variable definitions may refer to previously-defined variables. Predicates can combine ==, != and in tests using as many logical or, and, not operators and parentheses as necessary. Such “logical expressiveness” (and much more) could be obtained by reading configuration files interpreted as Python code, however:

• the syntax in such a case would not allow the almost-freeform options that are permitted by CondConfigParser (where the application chooses how to interpret the “options”);
• when an application interprets user configuration files as Python code, it exposes its users to some risk in case a malicious user manages to sneak code of his choice into a configuration file of the victim (think about configuration file snippets copied from Internet forums…).

Regarding the second point in particular, CondConfigParser never uses eval or exec to parse configuration files. It should thus be safe to work with any configuration file, including files prepared by malicious users.

Home page

CondConfigParser’s home page is located at:

http://frougon.net/projects/CondConfigParser/

(it was on people.via.ecp.fr before April 30, 2016)

Requirements

This version of CondConfigParser requires Python 3.4 or later.

Installation from source also requires setuptools, but this should only be a concern if you want to install without pip (if you have pip, you should already have setuptools; and if not, installing pip is likely to cause setuptools to be installed at the same time).

Debian package

If you are a Debian user, you can install CondConfigParser using the following lines in your /etc/apt/sources.list:

deb http://frougon.net/debian-ffgo unstable main
deb-src http://frougon.net/debian-ffgo unstable main

The package is named python3-condconfigparser. A package for Debian stable is also available. If this is what you want, just replace unstable with buster, or whatever is the codename of the current Debian stable release, in the sources.list lines given above.

The Release files in this repository are signed with Florent Rougon’s OpenPGP key . After downloading this key, be sure to verify that this is the same key as served by Github over https (you’ll need to add a trailing newline to the latter to ensure byte-for-byte equality). Once you’ve verified that this is the right key, you can add it to your apt keyring using apt-key add /path/to/file, as root. This allows apt to authenticate the packages. If you don’t do this, the installation should still be possible but with warnings and, of course, reduced security.

Quick installation instructions

This section describes installation from source. If you want to install from a Debian package instead, see above.

If you have a working pip setup, you should be able to install CondConfigParser with:

pip install CondConfigParser

(pip install condconfigparser also works)

When doing so, make sure that your pip executable runs with the Python 3 installation you want to install CondConfigParser for.

For more detailed instructions, you can read the INSTALL.txt file from a release tarball. You may also want to consult the “Installing Python Modules” chapter of the Python documentation and the pip documentation.

Download

Typical installations with pip automatically download the latest release from PyPI. However, in some cases, you may want to download a wheel package, tarball or zip file yourself in order to install it later, possibly on a different machine. You may get such files from PyPI or from Florent Rougon’s home page (the former should normally be favored over the latter, as it is served over https).

Git repository

CondConfigParser is maintained in a Git repository that can be cloned with:

git clone https://github.com/frougon/CondConfigParser

Documentation

The CondConfigParser Manual is written in reStructuredText format for the Sphinx documentation generator. The HTML documentation for the latest version of CondConfigParser as rendered by Sphinx is available at:

http://frougon.net/projects/CondConfigParser/doc/

The sources for the CondConfigParser Manual are located in the doc top-level directory of the CondConfigParser distribution, but the documentation build process pulls many parts from the source code, mainly docstrings.

To generate the documentation yourself from CondConfigParser’s code and the reStructuredText sources in the doc directory, first make sure you have Python 3.x, Sphinx and Make installed. Then, go to the doc directory and type, for instance:

make html

You will find the output in the _build/html subdirectory of doc. Sphinx can build the documentation in many other formats. For instance, if you have LaTeX installed, you can generate the CondConfigParser Manual in PDF format with:

make latexpdf

You can run make from the doc directory to see a list of the available formats. Run make clean to clean up after the documentation build process.

Note:

The Makefile uses a Python script (prepare-basic-pkg-info.py) to generate basic-pkg-info.rst from the top-level README.rst file. By default, this script is interpreted by the python3 executable. If you want to explicitely choose the interpreter to use, you can set the PYTHON Makefile variable like this:

make PYTHON=python3.4 html

Note that this only affects running of prepare-basic-pkg-info.py; the Python interpreter used by Sphinx in other places of the Makefile is determined by the sphinx-build executable that should be part of your Sphinx installation.

For those who have installed Sphinx but not Make, it is still possible to build the documentation with two commands such as:

python3 prepare-basic-pkg-info.py ../README.rst basic-pkg-info.rst
sphinx-build -b html -d _build/doctrees . _build/html

These commands must be run from the doc directory. Please refer to sphinx-build for more details.

Running the automated test suite

• If you want to run the automated test suite from an unpacked release tarball (or Git checkout), go to the root directory of that CondConfigParser distribution (the directory containing README.rst and the condconfigparser directory) and run:

  python3 -m unittest
  

  (assuming of course that you want to run the tests with an executable called python3).

  You may want to add the -v option at the end of the command in order to run the test suite in verbose mode.

• On the other hand, if you have already installed CondConfigParser for a given Python installation and you want to test the installed package, go to the directory containing the installed package and run:

  python3 -m unittest discover -t ..
  

  With a POSIX-style shell, you can combine both operations with the following command (that does not change your current directory):

  ( cd base_dir/lib/python3.4/site-packages/condconfigparser && \
    python3 -m unittest discover -t .. )
  

  This command is given for a Python 3.4 installation:

  • rooted at base_dir (typically /usr, /usr/local, /opt/pythonX.Y [on Unix-like systems] or a directory containing a Python venv or virtualenv)
  • using the python3 executable.

  You may want to add the -v option after the discover argument in order to run the test suite in verbose mode.

A successful run of the test suite looks like this:

% python3 -m unittest
.......
----------------------------------------------------------------------
Ran 7 tests in 0.052s

OK
% echo $?
0
%

In the above output, each dot represents a successful test. The echo $? command shows the zero exit status, indicating success for all tests. In case of a failure, the exit status is non-zero.

It is also possible to ask setuptools to run the test suite (by default in verbose mode, cf. the corresponding documentation). For instance:

python3 setup.py test