CODEWITHSUNDEEP
pythonconfigparser
emesday
emesday

Reputation: 6186

How to use variables already defined in ConfigParser

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.

Upvotes: 17

Views: 19281

Answers (3)

Franck Dernoncourt
Franck Dernoncourt

Reputation: 83187

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}

Upvotes: 8

Rod
Rod

Reputation: 55772

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 line

would 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

Upvotes: 25

Gareth McCaughan
Gareth McCaughan

Reputation: 19981

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.)

Upvotes: 11

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