def __init__(self, filename=None, sign=False, verify=False):
        """
        Initialise an instance using a (valid) filename.
        """
        self.sign = sign
        self.should_verify = verify
        self.buildver = ''
        self.pyver = [PYVER]
        self.abi = ['none']
        self.arch = ['any']
        self.dirname = os.getcwd()
        if filename is None:
            self.name = 'dummy'
            self.version = '0.1'
            self._filename = self.filename
        else:
            m = NAME_VERSION_RE.match(filename)
            if m:
                info = m.groupdict('')
                self.name = info['nm']
                # Reinstate the local version separator
                self.version = info['vn'].replace('_', '-')
                self.buildver = info['bn']
                self._filename = self.filename
            else:
                dirname, filename = os.path.split(filename)
                m = FILENAME_RE.match(filename)
                if not m:
                    raise DistlibException('Invalid name or '
                                           'filename: %r' % filename)
                if dirname:
                    self.dirname = os.path.abspath(dirname)
                self._filename = filename
                info = m.groupdict('')
                self.name = info['nm']
                self.version = info['vn']
                self.buildver = info['bn']
                self.pyver = info['py'].split('.')
                self.abi = info['bi'].split('.')
                self.arch = info['ar'].split('.')

        Initialise an instance using a (valid) filename.
        
product/gradle-plugin/src/main/python/pip/_vendor/distlib/wheel.py