typecheck.py 文件源码

def _instancecheck_impl(self, value, info: Info) -> InfoMsg:
        if not isinstance(value, str) or value == "":
            return info.errormsg(self)
        value = os.path.expanduser(value)
        if self.allow_std and value == "-" and (self.constraint is None or self.constraint(value)):
            return info.wrap(True)
        is_valid = True
        if os.path.exists(value):
            if os.path.isfile(value) and os.access(os.path.abspath(value), os.W_OK)\
                    and (self.constraint is None or self.constraint(value)):
                return info.wrap(True)
            return info.errormsg(self)
        if not self.allow_non_existent:
            return info.errormsg(self, "File doesn't exist")
        abs_name = os.path.abspath(value)
        dir_name = os.path.dirname(abs_name)
        if os.path.exists(dir_name) and os.access(dir_name, os.EX_OK) and os.access(dir_name, os.W_OK) \
            and (self.constraint is None or self.constraint(value)):
            return info.wrap(True)
        return info.errormsg(self)