def __init__(self, file, mode="r", compression=ZIP_STORED, allowZip64=False):
        if mode not in ("r", "w", "a"):
            raise RuntimeError('ZipFile() requires mode "r", "w", or "a"')

        if compression == ZIP_STORED:
            pass
        elif compression == ZIP_DEFLATED:
            if not zlib:
                raise RuntimeError,\
                      "Compression requires the (missing) zlib module"
        else:
            raise RuntimeError, "That compression method is not supported"

        self._allowZip64 = allowZip64
        self._didModify = False
        self.debug = 0  # Level of printing: 0 through 3
        self.NameToInfo = {}    # Find file info given name
        self.filelist = []      # List of ZipInfo instances for archive
        self.compression = compression  # Method of compression
        self.mode = key = mode.replace('b', '')[0]
        self.pwd = None
        self.comment = ''

        # Check if we were passed a file-like object
        if isinstance(file, basestring):
            self._filePassed = 0
            self.filename = file
            modeDict = {'r' : 'rb', 'w': 'wb', 'a' : 'r+b'}
            try:
                self.fp = open(file, modeDict[mode])
            except IOError:
                if mode == 'a':
                    mode = key = 'w'
                    self.fp = open(file, modeDict[mode])
                else:
                    raise
        else:
            self._filePassed = 1
            self.fp = file
            self.filename = getattr(file, 'name', None)

        if key == 'r':
            self._GetContents()
        elif key == 'w':
            pass
        elif key == 'a':
            try:                        # See if file is a zip file
                self._RealGetContents()
                # seek to start of directory and overwrite
                self.fp.seek(self.start_dir, 0)
            except BadZipfile:          # file is not a zip file, just append
                self.fp.seek(0, 2)
        else:
            if not self._filePassed:
                self.fp.close()
                self.fp = None
            raise RuntimeError, 'Mode must be "r", "w" or "a"'
Open the ZIP file with mode read "r", write "w" or append "a".
dataset/ETHPy150Open deanhiller/databus/webapp/play1.3.x/python/Lib/zipfile.py/ZipFile.__init__