I'm using ConfigParser in Python
config.ini is
[general]
name: my_name
base_dir: /home/myhome/exp
exe_dir: ${base_dir}/bin
Here I want exp_dir becomes /home/myhome/exp/bin not ${base_dir}/bin.
It means ${base_dir} would be substituted to /home/myhome/exp automatically.
You can use ConfigParser interpolation
On top of the core functionality, SafeConfigParser supports interpolation. This means values can contain format strings which refer to other values in the same section, or values in a special DEFAULT section. Additional defaults can be provided on initialization.
For example:
[My Section] foodir: %(dir)s/whatever dir=frob long: this value continues in the next linewould resolve the %(dir)s to the value of dir (frob in this case). All reference expansions are done on demand.
Your example becomes:
[general]
name: my_name
base_dir: /home/myhome/exp
exe_dir: %(base_dir)s/bin
Instead of "${foo}", write "%(foo)s". (See http://docs.python.org/library/configparser.html and search for "interpolation". This works for either an ordinary ConfigParser or a SafeConfigParser.)
s after the %(foo) drove me crazy. Sometimes you've got to look at the source first, before you realize it's in the docs, too! ;-)In Python 3, you can use ${base_dir}/bin, and the extended interpolation allows you to use variables from other sections. Example:
[Common]
home_dir: /Users
library_dir: /Library
system_dir: /System
macports_dir: /opt/local
[Frameworks]
Python: 3.2
path: ${Common:system_dir}/Library/Frameworks/
[Arthur]
nickname: Two Sheds
last_name: Jackson
my_dir: ${Common:home_dir}/twosheds
my_pictures: ${my_dir}/Pictures
python_dir: ${Frameworks:path}/Python/Versions/${Frameworks:Python}
configparser.ConfigParser(interpolation=configparser.ExtendedInterpolation())