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iniherit 0.2.0

A ConfigParser subclass with file-specified inheritance.

Latest Version: 0.3.3

Adds INI-file inheritance to ConfigParser. Note that although it effectively behaves very similarly to passing multiple files to ConfigParser’s read() method, that requires changing the code at that point. If that is not feasible, or the INI files should dictate inheritance themselves, then the iniherit package is a better alternative.

TL;DR

Given the following two files, base.ini:

[app:main]
name = My Application Name

and 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.SafeConfigParser()
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.

The command-line program iniherit allows flattening of INI files (i.e. collapsing all inheritance rules), optionally in “watch” mode:

$ iniherit --watch --interval 2 --verbose input.ini output.ini
INFO:iniherit.cli:"source.ini" changed; updating output...
INFO:iniherit.cli:"inherited-file.ini" changed; updating output...
^C

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

  • After an inherit-enabled INI file is loaded, the ConfigParser no longer has knowledge of where a particular option was loaded from or how it was derived. For this reason, when the write method is called, the ConfigParser generates an INI file without inheritance. In other words, it flattens the inheritance tree.
 
File Type Py Version Uploaded on Size
iniherit-0.2.0.tar.gz (md5) Source 2014-04-16 11KB
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