[Python-Dev] New regex module for 3.2? (original) (raw)

MRAB python at mrabarnett.plus.com
Fri Jul 9 02:35:14 CEST 2010

Nick Coghlan wrote:

On Fri, Jul 9, 2010 at 7:54 AM, MRAB <python at mrabarnett.plus.com> wrote:

You should be able to replace:

import re with: import regex as re and still have everything work the same, ie it's backwards compatible with re. That's not what I'm asking. I'm asking what happens if you take an existing Python installation's re module, move it aside, and drop regex in its place as "re.py". Doing that and then running Python's own test suite as well as the test suites of major Python applications and frameworks like Twisted, Zope and Django would provide solid evidence that the new version really is backwards compatible, rather than that it is meant to be backwards compatible. I had to recompile the .pyd to change its internal name from "regex" to "re", but apart from that it passed Python's own test suite except for where I expected it to fail:

  1. Some of the inline flags are scoped; for example, putting "(?i)" at the end of a regex will now have no effect because it's no longer a global, all-or-nothing, flag.

  2. The .sub method will treat unmatched groups in an expansion as empty strings. The re module raises an exception in such cases, which means that users currently need a workaround.

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