[New-bugs-announce] [issue17125] tokenizer.tokenize passes a bytes object to str.startswith

Tyler Crompton report at bugs.python.org
Mon Feb 4 17:51:28 CET 2013

New submission from Tyler Crompton:

Line 402 in lib/python3.3/tokenize.py, contains the following line:

    if first.startswith(BOM_UTF8):

BOM_UTF8 is a bytes object. str.startswith does not accept bytes objects. I was able to use tokenize.tokenize only after making the following changes:

Change line 402 to the following:

    if first.startswith(BOM_UTF8.decode()):

Add these two lines at line 374:

        except AttributeError:
            line_string = line

Change line 485 to the following:

                line = line.decode(encoding)
            except AttributeError:

I do not know if these changes are correct as I have not fully tested this module after these changes, but it started working for me. This is the meat of my invokation of tokenize.tokenize:

import tokenize

with open('example.py') as file: # opening a file encoded as UTF-8
	for token in tokenize.tokenize(file.readline):

I am not suggesting that these changes are correct, but I do believe that the current implementation is incorrect. I am also unsure as to what other versions of Python are affected by this.

components: Library (Lib)
messages: 181349
nosy: Tyler.Crompton
priority: normal
severity: normal
status: open
title: tokenizer.tokenize passes a bytes object to str.startswith
type: behavior
versions: Python 3.3

Python tracker <report at bugs.python.org>

More information about the New-bugs-announce mailing list