Basic configparser usage

These are some examples on using ConfigParser, assuming the following INI file...

[SectionOne]
Status: Single
Name: Derek
Value: Yes
Age: 30
Single: True

[SectionTwo]
FavoriteColor = Green
[SectionThree]
FamilyName: Johnson

[Others]
Route: 66

>>> import ConfigParser
>>> Config = ConfigParser.ConfigParser()
>>> Config
<ConfigParser.ConfigParser instance at 0x00BA9B20>
>>> Config.read("c:\\tomorrow.ini")
['c:\\tomorrow.ini']
>>> Config.sections()
['Others', 'SectionThree', 'SectionOne', 'SectionTwo']
>>>

Explanation: We first import the configparser, tell it to read the file, and get a listing of the sections. Sections are listed in square brackets [].

Next, we are going to get some settings, after defining a helper function.

The Function:

def ConfigSectionMap(section):
    dict1 = {}
    options = Config.options(section)
    for option in options:
        try:
            dict1[option] = Config.get(section, option)
            if dict1[option] == -1:
                DebugPrint("skip: %s" % option)
        except:
            print("exception on %s!" % option)
            dict1[option] = None
    return dict1

Now the code:

>>> Name = ConfigSectionMap("SectionOne")['name']
>>> Age = ConfigSectionMap("SectionOne")['age']
>>> print "Hello %s. You are %s years old." % (Name, Age)
Hello Derek. You are 30 years old.

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This works great most of the time, but what about the "Value: Yes" and "Single: True" values? Those are booleans. They can be either True or False, Yes or No, 1 or 0, on or off. To read a boolean value, you use:  Config.getboolean(section, option)  Example, continuing from above:

>>> single = Config.getboolean("SectionOne", "single")
>>> single
True

You can also use getint(section, option) to get a number as an int. This may be easier to use than int(Config.get(section, option)) There is also getfloat which is used the same as getint, but, as you guessed, returns a float instead of an int.

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Notes on reading an INI file

lines beginning with a semicolon ';' a pound sign '#' or the letters 'REM' (uppercase or lowercase) will be ignored. You may use these for comments if you want. You cannot put a comment on an option line. It will only be treated as a comment if it is at the beginning of the line!

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Writing an INI file

When you write to an INI file, you will wipe out all comments.

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Assuming the config file doesn't exist yet, this is the code to create one:

# lets create that config file for next time...
cfgfile = open("c:\\next.ini",'w')

# add the settings to the structure of the file, and lets write it out...
Config.add_section('Person')
Config.set('Person','HasEyes',True)
Config.set('Person','Age', 50)
Config.write(cfgfile)
cfgfile.close()

Advanced configparser usage

ExtendedInterpolation

Using ExtendedInterpolation one can make use of cross-chapter flexible parameter values. For instance, using the following ini file:

[SectionOne]
Param1: Hello
Param2: World

[SectionTwo]
Param1: ${SectionOne:Param1} ${SectionOne:Param2}

[SectionThree]
Alpha: One
Bravo: Two
Charlie: ${Alpha} Mississippi

By setting _interpolation to ExtendedInterpolation() the values become dynamic.

>>> import configparser
>>> settings = configparser.ConfigParser()
>>> settings._interpolation = configparser.ExtendedInterpolation()
>>> settings.read('settings.ini')
['settings.ini']
>>> settings.sections()
['SectionOne', 'SectionTwo', 'SectionThree']
>>> settings.get('SectionTwo', 'Param1')
'Hello World'
>>> settings.get('SectionThree', 'Charlie')
'One Mississippi'

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