Where can I get the Python 2to3 library on Buildroot

Question

I get the following error when importing gmusicapi in Python 2.7 on a Buildroot Linux system:

>>> import gmusicapi
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "gmusicapi/__init__.py", line 4, in <module>
    from gmusicapi.clients import Webclient, Musicmanager, Mobileclient
  File "gmusicapi/clients/__init__.py", line 4, in <module>
    from gmusicapi.clients.webclient import Webclient
  File "gmusicapi/clients/webclient.py", line 5, in <module>
    from past.builtins import basestring
  File "past/__init__.py", line 88, in <module>
    from past.translation import install_hooks as autotranslate
  File "past/translation/__init__.py", line 41, in <module>
    from lib2to3.pgen2.parse import ParseError
ImportError: No module named lib2to3.pgen2.parse

Python can't find lib2to3. Neither can I ;-). Is there anywhere I can download this library? I'm using Buildroot, so I can't simply do pip installs.

This is not a duplicate of: How to use/install python 2to3?

According to the [docs](https://docs.python.org/2/library/2to3.html), "2to3 will usually be installed with the Python interpreter as a script. It is also located in the `Tools/scripts` directory of the Python root." — ForceBru, Jan 17 '18 at 16:36
What OS is this? How was Python installed? `lib2to3` is part of the *standard library*, and should have been installed automatically. For example, on Ubuntu, I'd expect the [`libpython2.7-stdlib` package](https://packages.ubuntu.com/search?suite=default&section=all&arch=any&keywords=libpython2.7-stdlib&searchon=names) (which contains `lib2to3`) to have been installed as a dependency of `python2.7`. — Martijn Pieters, Jan 17 '18 at 16:45
@ForceBru: I don't have this directory, also, I'd expect not a tool but a Python library, because Python code imports it. — svenema, Jan 17 '18 at 16:46
@MartijnPieters: Linux (Buildroot). Maybe it's in a library which has a misleading name, but there is nothing like lib2to3 or anything that points in that direction. — svenema, Jan 17 '18 at 16:47
@svenema, if your installation has the script, it must also have the library. If it doesn't, make sure you're using the official latest Python 2.7. — ForceBru, Jan 17 '18 at 16:47
Then this looks relevant: https://github.com/buildroot/buildroot/blob/master/package/python/0018-Add-an-option-to-disable-lib2to3.patch — Martijn Pieters, Jan 17 '18 at 22:19

Martijn Pieters · Accepted Answer · 2018-01-17T22:29:56.660

lib2to3 is a standard library, normally included with Python. However, the buildroot build system explicitly removes it.

I'm not certain if Buildroot actually lets you disable their patch; the python.mk file appears to hardcode the flag:

PYTHON_CONF_OPTS += \
    --without-cxx-main \
    --without-doc-strings \
    --with-system-ffi \
    --disable-pydoc \
    --disable-test-modules \
    --disable-lib2to3 \
    --disable-gdbm \
    --disable-tk \
    --disable-nis \
    --disable-dbm \
    --disable-pyo-build \
    --disable-pyc-build

and I don't see an option to add --enable-lib2to3 to override that. You may want to check with the Buildroot community if this is at all an option. Otherwise, I'd just edit that make file.

It's not ideal to use 2to3 on embedded systems, that's why it turned out it was disabled. — svenema, Jan 18 '18 at 22:02

score 0 · Answer 2 · answered Jan 17 '18 at 17:05

Workaround: patching the past library (source of the problem):

--- past/translation/__init__.py.orig   2017-09-24 08:23:47.646644743 +0200
+++ past/translation/__init__.py    2018-01-01 10:31:36.584576652 +0100
@@ -38,8 +38,32 @@
 import os
 import sys
 import copy
-from lib2to3.pgen2.parse import ParseError
-from lib2to3.refactor import RefactoringTool
+
+try:
+    from lib2to3.pgen2.parse import ParseError
+
+except ImportError:
+
+    class ParseError(SyntaxError):
+        pass
+
+try:
+    from lib2to3.refactor import RefactoringTool
+
+except ImportError:
+
+    class RefactoringTool:
+
+        def __init__(self, *args, **kwargs):
+            self._args = [repr(a) for a in args]
+            self._args += ["{}={!r}".format(k, v) for k, v in kwargs.items()]
+
+        def __repr__(self):
+            return "{}({})".format(self.__class__.__name__, ", ".join(self._args))
+
+        def refactor_string(self, *args, **kwargs):
+            raise NotImplementedError("dummy RefactoringTool")
+

 from libfuturize import fixes

found here: https://github.com/PythonCharmers/python-future/issues/209

If someone can point me to a downloadable lib2to3 I'll accept that answer, for now this workaround will do the trick.

Please post your question to Buildroot's mailing list. – yegorich Jan 18 '18 at 09:15 — yegorich, Jan 18 '18 at 09:15

score 0 · Answer 3 · answered Jul 12 '22 at 12:00

0

I resolved this issue by running below command on my Ubuntu 20.04 machine: sudo apt-get install -y python3.7-lib2to3

answered Jul 12 '22 at 12:00

Jill

47
8

The question is specifically about how to install it on a Buildroot system. – snakecharmerb Jul 16 '22 at 11:27

Where can I get the Python 2to3 library on Buildroot

3 Answers3