iniherit 0.1.4

Project Info

• Project Page: https://github.com/cadithealth/iniherit

• Bug Tracking: https://github.com/cadithealth/iniherit/issues

TL;DR

Given the following two files:

## file "base.ini"

[app:main]
name = My Application Name

## file "config.ini"

[DEFAULT]
# the following will cause both "base.ini" and "override.ini" to be
# inherited. the "?" indicates that "override.ini" will be ignored
# if not found; otherwise an error would occur.
%inherit = base.ini ?override.ini

Then the following code will pass the assert:

import iniherit
cfg = iniherit.IniheritSafeConfigParser()
cfg.read('config.ini')

assert cfg.get('app:main', 'name') == 'My Application Name'

Alternatively, the global ConfigParser can be altered to support inheritance:

import iniherit
iniherit.mixin.install_globally()

import ConfigParser
cfg = ConfigParser.SafeConfigParser()
cfg.read('config.ini')

assert cfg.get('app:main', 'name') == 'My Application Name'

Note that the call to install_globally() must be invoked before any other module imports ConfigParser for the global override to have an effect.

Installation

Install iniherit via your favorite PyPI package manager works as follows:

$ pip install iniherit

Inheritance Mechanism

INI file inheritance with the iniherit package:

• To add inheritance to an INI file, add an %inherit option to the “DEFAULT” section of the INI file to inherit all sections of the specified files. Example:

  [DEFAULT]
  %inherit  = base.ini
  def_var   = Overrides the "def_var" setting, if present,
    in the "DEFAULT" section of "base.ini".
  
  [my-app]
  sect_var  = Overrides the "sect_var" setting, if present,
    in the "my-app" section of "base.ini". Other sections in
    "base.ini" will also be inherited, even if not specified
    here.

• The %inherit option points to a space-separated, URL-encoded, list of files to inherit values from, whose values are loaded depth-first, left-to-right. For example:

  [DEFAULT]
  %inherit = base.ini file-with%20space.ini

• To inherit only a specific section, add the %inherit option directly to the applicable section. By default, the section by the same name will be loaded from the other files, unless the filename is suffixed with square-bracket enclosed (“[” … “]”), URL-encoded, section name. Example:

  [section]
  %inherit = base.ini override.ini[other%20section]

  In this case, the “section” section in “base.ini” will be inherited, followed by the “other section” from “override.ini”.

  Note that if the inherited section includes interpolation references to the DEFAULT section, these will NOT be carried over! In other words, inheritance currently ONLY inherits the actual values, not the interpreted values. Be warned, as this can lead to surprising results!

  If a filename has “[” in the actual name, it can be URL-encoded.

• Filenames, if specified relatively, are taken to be relative to the current INI file.

• If a filename is prefixed with “?”, then it will be loaded optionally: i.e. if the file does not exist, it will be silently ignored. If the file does NOT have a “?” prefixed and cannot be found, then an IOError will be raised. Note that this is unlike standard ConfigParser.read() behavior, which silently ignores any files that cannot be found.

  If a filename has “?” as its first character, it can be URL-encoded.

• Note that the actual name of the inherit option can be changed by changing either iniherit.parser.DEFAULT_INHERITTAG for a global effect, or ConfigParser.IM_INHERITTAG for a per-instance effect.

Gotchas

• Because of how the INI files are loaded and manipulated, the IniheritConfigParser’s write method is disabled. This is because the parser cannot know in which inherited file to save any value changes. For writing INI files, you should use other ConfigParser subclasses, such as ConfigParser.RawConfigParser.