[Tutor] The __setattr__ method

[steve]

Hi there,

On Monday 27 August 2001 23:33, you wrote:
> Hey everyone. I am working on a module to provide access to an mp3 file=
's
> ID3 tags. A class seemed to be the best way to represent the informatio=
n
> represented in an ID3 tag's fields. However, i would like to be able to
> tell when the information in the tag is changed so that the information=
 can
> be written back into the ID3 tag. This is my dilemma.
> .....
> .....
> <snip>

 Thought I'd just mention it,....I've written a similar module, you can h=
ave=20
a look at it at the Useless Python site:
 http://www.lowerstandard.com/python/uselesspython12.html

I have used a UserDict to represent the IDTag data, like so:
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
class mp3file(UserDict):
    tagDataMap =3D {
        "title"   : (  3,  33, stripnulls),
        "artist"  : ( 33,  63, stripnulls),
        "album"   : ( 63,  93, stripnulls),
        "year"    : ( 93,  97, stripnulls),
        "comment" : ( 96, 126, stripnulls),
        "genre"   : (127, 128, ord) }

    def __init__(self, flname =3D None):
        UserDict.__init__(self)
        self["name"] =3D flname
        self.__parse()
        self.dir, file =3D os.path.split(flname)
        self["new_name"] =3D file

    def __parse(self):
        try:
            fl =3D open(self["name"], "r")
            try:
                fl.seek(-128, 2)
                tagdata =3D fl.read()
            finally:
                fl.close()
            if tagdata[:3] =3D=3D 'TAG':
                for tag, (start, end, func) in self.tagDataMap.items():
                    self[tag] =3D func(tagdata[start:end])
            else:
                for tag in self.tagDataMap.keys():
                    self[tag] =3D ''
            except IOError,msg:
                raise BigBooBoo("Error opening file %s\n%s" % (flname, ms=
g))
=20
    def __setitem__(self, key, item):
        if key in [ "title", "artist", "album", "comment" ]:
            item =3D item[:30]
        elif key =3D=3D "year":
            item =3D item[:4]
        elif key =3D=3D "genre":
            item =3D self.getGenre(item)
        self.data[key] =3D item

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
It might not be all that clear b'cos I have no comments within the file a=
bout=20
why I do what I do, but if you have questions about anything you could al=
ways=20
ask.

 Hope you find it interesting

Peace
Steve
          =20
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