Closing file opened by ConfigParser

Question

I have the following:

config = ConfigParser()
config.read(\'connections.cfg\')
sections = config.sections()

How can I close the file opened

Answer 1

ConfigParser.read(filenames) actually takes care of that for you.

While coding I have encountered this issue and found myself asking myself the very same question:

Reading basically means I also have to close this resource after I'm done with it, right?

I read the answer you got here suggesting to open the file yourself and use config.readfp(fp) as an alternative. I looked at the documentation and saw that indeed there is no ConfigParser.close(). So I researched a little more and read the ConfigParser code implementation itself:

def read(self, filenames):
    """Read and parse a filename or a list of filenames.

    Files that cannot be opened are silently ignored; this is
    designed so that you can specify a list of potential
    configuration file locations (e.g. current directory, user's
    home directory, systemwide directory), and all existing
    configuration files in the list will be read.  A single
    filename may also be given.

    Return list of successfully read files.
    """
    if isinstance(filenames, basestring):
        filenames = [filenames]
    read_ok = []
    for filename in filenames:
        try:
            fp = open(filename)
        except IOError:
            continue
        self._read(fp, filename)
        fp.close()
        read_ok.append(filename)
    return read_ok

This is the actual read() method from ConfigParser.py source code. As you can see, 3rd line from the bottom, fp.close() closes the opened resource after its usage in any case. This is offered to you, already included in the box with ConfigParser.read() :)

Answer 2

To test your suspicion, use ConfigParser.readfp() and handle opening and closing of the file by yourself. Make the readfp call after the changes are made.

config = ConfigParser()
#...on each change
fp = open('connections.cfg')
config.readfp(fp)
fp.close()
sections = config.sections()

Answer 3

Use readfp instead of read:

with open('connections.cfg') as fp:
    config = ConfigParser()
    config.readfp(fp)
    sections = config.sections()

Answer 4

The difference between ConfigParser and RawConfigParser is that ConfigParser will attempt to "magically" expand references to other config variables, like so:

x = 9000 %(y)s
y = spoons

In this case, x will be 9000 spoons, and y will just be spoons. If you need this expansion feature, the docs recommend that you instead use SafeConfigParser. I don't know what exatly the difference between the two is. If you don't need the expansion (you probably don't) just need RawConfigParser.