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pythonconfigparser

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.

Solution

  • 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