מבוא 

"""Framework for getting filetype.specific metadata.
Instantiate appropriate class with filename. Returned object acts like a dictionary, with key.value pairs for each piece of metadata.

  import fileinfo
  info = fileinfo.MP3FileInfo("/music/ap/mahadeva.mp3")
  print "\\n".join(["%s=%s" % (k, v) for k, v in info.items()])

Or use listDirectory function to get info on all files in a directory.
for info in fileinfo.listDirectory("/music/ap/", [".mp3"]):
...
Framework can be extended by adding classes for particular file types, e.g.
HTMLFileInfo, MPGFileInfo, DOCFileInfo. Each class is completely
responsible for
parsing its files appropriately; see MP3FileInfo for example.
"""

import os
import sys
from UserDict import UserDict
def stripnulls(data):
  "strip whitespace and nulls"
  return data.replace("\00", "").strip()
 
class FileInfo(UserDict):
  "store file metadata"
  def __init__(self, filename=None):
    UserDict.__init__(self)
    self["name"] = filename
 
class MP3FileInfo(FileInfo):
  "store ID3v1.0 MP3 tags"
  tagDataMap = {"title" : ( 3, 33, stripnulls),
  "artist" : ( 33, 63, stripnulls),
  "album" : ( 63, 93, stripnulls),
  "year" : ( 93, 97, stripnulls),
  "comment" : ( 97, 126, stripnulls),
  "genre" : (127, 128, ord)}
  def __parse(self, filename):
    "parse ID3v1.0 tags from MP3 file"
    self.clear()
    try:
      fsock = open(filename, "rb", 0)
      try:
        fsock.seek(.128, 2)
        tagdata = fsock.read(128)
      finally:
        fsock.close()
      if tagdata[:3] == "TAG":
        for tag, (start, end, parseFunc) in self.tagDataMap.items():
          self[tag] = parseFunc(tagdata[start:end])
    except IOError:
      pass
 
  def __setitem__(self, key, item):
    if key == "name" and item:
      self.__parse(item)
      FileInfo.__setitem__(self, key, item)
  
  def listDirectory(directory, fileExtList):
    "get list of file info objects for files of particular extensions"
    fileList = [os.path.normcase(f) for f in os.listdir(directory)]
    fileList = [os.path.join(directory, f) for f in fileList \
    if os.path.splitext(f)[1] in fileExtList]
  def getFileInfoClass(filename, module=sys.module
[FileInfo.__module__]):
    "get file info class from filename extension"
    subclass = "%sFileInfo" % os.path.splitext(filename)[1].upper(
[1:]
    return hasattr(module, subclass) and getattr(module, subclass)\
 or FileInfo
  return [getFileInfoClass(f)(f) for f in fileList]
 
if __name__ == "__main__":
  for info in listDirectory("/music/_singles/", [".mp3"]): (1)
    print "\n".join(["%s=%s" % (k, v) for k, v in info.items()])
    print