Inifile: an ini-style configuration template

IniFile is a ini-style configuration module that uses a template to define the configuration file structure. The code below includes some samples. Feel free to use as-is.

"""

inifile.py



Library for reading and writing ini-style config files. The ini file

structure is provided as a class, with nested classes acting as the

sections.



Usage:



    # declare the ini file structure using a class statement

    class MyIni(IniFile):

        one = TypedAttribute(1)

        two = TypedAttribute(2)

        three = TypedAttribute(3, name='triple')

        class NestedSection(IniSection):

            str1 = TypedAttribute('one', name='str_one')

            str2 = TypedAttribute('two', name='str_two')



    # create a configuration instance

    config = MyIni()



    # read the config file

    inifile.load()

      or

    inifile.read()



    # write it back

    inifile.save()

      or

    inifile.write()



-- sample ini file --

[server]

socketPort = 8080

threadPool = 10



[staticContent]

bitmaps = /var/local/bitmaps



[session]

storageType=ram



"""



from metatemplate import GenericTemplate, GenericAttribute,     TypedAttribute, next_attribute_id

from types import StringType

from inspect import isclass

import re



debug_inifile = 0



class IniSection(GenericTemplate):



    re_section = re.compile(r'^\[(.*)\]')

    re_unquote = re.compile(r'^(?P[\"\']?)(?P.*)(?P=openquote)$')



    def log(self, line):

        """simple auxiliary log functions"""

        if debug_inifile:

            # should use the logger interface!

            print line



    def unquote(self, value):

        """unquotes strings reads from the config file"""

        return self.re_unquote.match(value).groupdict()['content']



    def read(self, fileobj):

        """reads the config file info from a file-like object"""



        for line in fileobj:

            #attr_name_list = [f[0] for f in self.__fields__]

            attr_name_list = self.__attr__.keys()

            line = line.strip()

            if not line: continue

            matchresult = self.re_section.match(line)

            if matchresult:

                sectionname = matchresult.group(1)

                self.log('Found section: %s' % sectionname)

                while sectionname in attr_name_list:

                    # found a known section

                    section = getattr(self, sectionname, None)

                    if isinstance(section, IniSection):

                        self.log('Section: %s' % sectionname)

                        sectionname = section.read(fileobj)

                        self.log('Section finished: %s' % sectionname)

                    else:

                        # section name does refer to a section object

                        # ?should it raise a fatal exception/warning?

                        self.log('Section error: %s' % sectionname)

                        sectionname = None

                else:

                    # section is not a child of this node, it's a

                    # sibling; returns the section name

                    self.log('Unknown section: %s' % sectionname)

                    return sectionname

            else:

                # found an attribute

                name, value = line.split('=',1)

                name = name.strip()

                value = value.strip()

                self.log('Normal attribute: %s = %s' % (name, value))



                # retrieves the attribute using the alternative name

                cls_attr_tuple = self.__class__.__attr__.get(name, None)

                if not cls_attr_tuple:

                    # invalid attribute found in the config file!

                    # ? should it cause a exception or warning ?

                    print '1:', self.__class__.__fields__

                    print '2:', self.__class__.__attr__

                    print '3:', self.__class__.__attr__[name]

                    print '4:', cls_attr_tuple

                    print 'Error - Attribute not found: %s' % (name,)

                    raise KeyError



                # retrieves the name used for binding

                cls_attr_name, cls_attr = cls_attr_tuple



                # sets the instance value

                if isinstance(cls_attr, GenericAttribute):

                    setattr(self, cls_attr_name, self.unquote(value))

                else:

                    # invalid attribute found in the config file!

                    # ? should it cause a exception or warning ?

                    raise KeyError



    def write(self, fileobj, _initialpos = None):

        """writes the config file info to a file-like object"""

        if not _initialpos:

            _initialpos = fileobj.tell()



        for fname, fobj in self.__fields__:

            # looks at the class to retrieve the attribute definition

            cls_attr = getattr(self.__class__, fname, None)

            # gets the attribute value stored in the instance

            ins_attr = getattr(self, fname, None)



            # is a subsection?

            if isclass(cls_attr) and issubclass(cls_attr, IniSection):

                # writes an empty line before the section (if needed)

                currentpos = fileobj.tell()

                if currentpos > _initialpos:

                    fileobj.write('\n')



                # writes section name & section contents

                fileobj.write('[%s]\n' % fname)

                ins_attr.write(fileobj, _initialpos = currentpos)



            # is an attribute?

            elif isinstance(cls_attr, GenericAttribute):

                fileobj.write('%s=%s\n' % (cls_attr.name, str(ins_attr)))



class IniFile(IniSection):

    def load(self, fname=None):

        if not fname:

            fname = self.name + '.ini'

        inifile = open(fname, 'r')

        self.read(inifile)

        inifile.close()



    def save(self, fname=None):

        if not fname:

            fname = self.name + '.ini'

        inifile = open(fname, 'w')

        self.write(inifile)

        inifile.close()