Preferences Script

import copy
import shutil

class Preferences:
    """Simple Class for reading and writing preferences to a file"""

    _pref = {}
    _sections = []

    def __init__(self, fileName):
        self._file = fileName
        self._loadPreferences_()

    def __repr__(self):
        """Defines what happens when the object is printed out"""
        out = ""

        for sk,sv in self._pref.items():
            out += "[%s]\n" % (sk)
            for ik,iv in sv.items():
                out += "%s = %s\n" % (ik,iv)

        return out

    def _loadPreferences_(self):
        """
        Reads in the preferences's from a file
        Ignores lines that start with # or ; (comments)
        Comments must be on their own line
        """

        pref = {}
        pref["Main"] = {}
        sections = ["Main"]
        curSection = "Main"
        fh = open(self._file,"r+")

        for line in fh:
            if line[:1] == '#' or line == "\n" or line[:1] == ';':
                continue

            if line[:1] == '[':
                curSection = line.strip()[1:-1]
                sections.append(line.strip()[1:-1])
                pref[curSection] = {}
                continue

            p = line.split('=')
            pref[curSection][p[0].replace('"', '').strip()] = p[1].replace('"', '').strip()

        fh.close()

        self._pref = pref
        self._sections = sections


    def getPreferences(self):
        """
        Returns a Deepcopy of a Dictionary
        Contains Dictionaries for each section in preference file
        """
        return copy.deepcopy(self._pref)

    def savePreferences(self, pref, backup = False):
        """
        Takes the supplied dictionary and writes it to file
        Curently overrides orginal file
        Optionaly makes backup of original file
        """
        lines = ""
        sections = []

        for k in pref.keys():
            sections.append(k)

        sections.insert(0, sections.pop(sections.index('Main')))

        for section in sections:
            if not section == 'Main':
                lines += "\n[%s]\n" % (section)

            for k,v in pref[section].items():
                lines += "%s = %s\n" % (k,v)

        if backup:
            #Do Backup
            shutil.copy2(self._file,"%s.bak" % (self._file))

        fh = open(self._file, "w")
        fh.write(lines)
        fh.close()

    def listSections(self):
        """Lists the sections in a preference file"""
        return self._sections

    def getDifferences(self, oldPref, newPref):
        """
        Compares two dictionaries and returns a tuple
        The tuple contains 3 dictionaries(changed, inserted, deleted)
        """
        changedPref = {}
        insertPref = {}
        delPref = {}

        for k,v in newPref.iteritems():
            if (k not in oldPref):
                insertPref[k] = v
                continue

            if (not oldPref[k] == v):
                changedPref[k] = v

        for k,v in oldPref.iteritems():
            if (k not in newPref):
                delPref[k] = v

        return updatePref, insertPref, delPref


if __name__ == "__main__":
    tp = Preferences("test2.ini")
    pref = tp.getPreferences()
    pref["New"] = {}
    pref["New"]["Bad"] = "Good"
    tp.savePreferences(pref)