def accepts(exception,**types): def check_accepts(f): assert len(types) == f.func_code.co_argcount, \ 'accept number of arguments not equal with function number of arguments in "%s"' % f.func_name def new_f(*args, **kwds): for i,v in enumerate(args): if types.has_key(f.func_code.co_varnames[i]) and \ not isinstance(v, types[f.func_code.co_varnames[i]]): raise exception("arg '%s'=%r does not match %s" % \ (f.func_code.co_varnames[i],v,types[f.func_code.co_varnames[i]])) del types[f.func_code.co_varnames[i]] for k,v in kwds.iteritems(): if types.has_key(k) and not isinstance(v, types[k]): raise exception("arg '%s'=%r does not match %s" % \ (k,v,types[k])) return f(*args, **kwds) new_f.func_name = f.func_name return new_f return check_accepts def exmaple(): @accepts(Exception,a=int,b=list,c=(str,unicode)) def test(a,b=None,c=None) print 'ok' test(13,c=[],b='df')