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+{
+ "cells": [
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "# Cheat Sheet: Writing Python 2-3 compatible code"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "- **Copyright (c):** 2013-2019 Python Charmers Pty Ltd, Australia.\n",
+ "- **Author:** Ed Schofield.\n",
+ "- **Licence:** Creative Commons Attribution.\n",
+ "\n",
+ "A PDF version is here: http://python-future.org/compatible_idioms.pdf\n",
+ "\n",
+ "This notebook shows you idioms for writing future-proof code that is compatible with both versions of Python: 2 and 3. It accompanies Ed Schofield's talk at PyCon AU 2014, \"Writing 2/3 compatible code\". (The video is here: <http://www.youtube.com/watch?v=KOqk8j11aAI&t=10m14s>.)\n",
+ "\n",
+ "Minimum versions:\n",
+ "\n",
+ " - Python 2: 2.6+\n",
+ " - Python 3: 3.3+"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Setup"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "The imports below refer to these ``pip``-installable packages on PyPI:\n",
+ "\n",
+ " import future # pip install future\n",
+ " import builtins # pip install future\n",
+ " import past # pip install future\n",
+ " import six # pip install six\n",
+ "\n",
+ "The following scripts are also ``pip``-installable:\n",
+ "\n",
+ " futurize # pip install future\n",
+ " pasteurize # pip install future\n",
+ "\n",
+ "See http://python-future.org and https://pythonhosted.org/six/ for more information."
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Essential syntax differences"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### print"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "print 'Hello'"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3:\n",
+ "print('Hello')"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "To print multiple strings, import ``print_function`` to prevent Py2 from interpreting it as a tuple:"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "print 'Hello', 'Guido'"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3:\n",
+ "from __future__ import print_function # (at top of module)\n",
+ "\n",
+ "print('Hello', 'Guido')"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "print >> sys.stderr, 'Hello'"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3:\n",
+ "from __future__ import print_function\n",
+ "\n",
+ "print('Hello', file=sys.stderr)"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "print 'Hello',"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3:\n",
+ "from __future__ import print_function\n",
+ "\n",
+ "print('Hello', end='')"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### Raising exceptions"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "raise ValueError, \"dodgy value\""
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3:\n",
+ "raise ValueError(\"dodgy value\")"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "Raising exceptions with a traceback:"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "traceback = sys.exc_info()[2]\n",
+ "raise ValueError, \"dodgy value\", traceback"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 3 only:\n",
+ "raise ValueError(\"dodgy value\").with_traceback()"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: option 1\n",
+ "from six import reraise as raise_\n",
+ "# or\n",
+ "from future.utils import raise_\n",
+ "\n",
+ "traceback = sys.exc_info()[2]\n",
+ "raise_(ValueError, \"dodgy value\", traceback)"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: option 2\n",
+ "from future.utils import raise_with_traceback\n",
+ "\n",
+ "raise_with_traceback(ValueError(\"dodgy value\"))"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "Exception chaining (PEP 3134):"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 3,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Setup:\n",
+ "class DatabaseError(Exception):\n",
+ " pass"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 3 only\n",
+ "class FileDatabase:\n",
+ " def __init__(self, filename):\n",
+ " try:\n",
+ " self.file = open(filename)\n",
+ " except IOError as exc:\n",
+ " raise DatabaseError('failed to open') from exc"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 16,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3:\n",
+ "from future.utils import raise_from\n",
+ "\n",
+ "class FileDatabase:\n",
+ " def __init__(self, filename):\n",
+ " try:\n",
+ " self.file = open(filename)\n",
+ " except IOError as exc:\n",
+ " raise_from(DatabaseError('failed to open'), exc)"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 17,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Testing the above:\n",
+ "try:\n",
+ " fd = FileDatabase('non_existent_file.txt')\n",
+ "except Exception as e:\n",
+ " assert isinstance(e.__cause__, IOError) # FileNotFoundError on Py3.3+ inherits from IOError"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### Catching exceptions"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "try:\n",
+ " ...\n",
+ "except ValueError, e:\n",
+ " ..."
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3:\n",
+ "try:\n",
+ " ...\n",
+ "except ValueError as e:\n",
+ " ..."
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### Division"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "Integer division (rounding down):"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "assert 2 / 3 == 0"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3:\n",
+ "assert 2 // 3 == 0"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "\"True division\" (float division):"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 3 only:\n",
+ "assert 3 / 2 == 1.5"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3:\n",
+ "from __future__ import division # (at top of module)\n",
+ "\n",
+ "assert 3 / 2 == 1.5"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "\"Old division\" (i.e. compatible with Py2 behaviour):"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "a = b / c # with any types"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3:\n",
+ "from past.utils import old_div\n",
+ "\n",
+ "a = old_div(b, c) # always same as / on Py2"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### Long integers"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "Short integers are gone in Python 3 and ``long`` has become ``int`` (without the trailing ``L`` in the ``repr``)."
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only\n",
+ "k = 9223372036854775808L\n",
+ "\n",
+ "# Python 2 and 3:\n",
+ "k = 9223372036854775808"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only\n",
+ "bigint = 1L\n",
+ "\n",
+ "# Python 2 and 3\n",
+ "from builtins import int\n",
+ "bigint = int(1)"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "To test whether a value is an integer (of any kind):"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "if isinstance(x, (int, long)):\n",
+ " ...\n",
+ "\n",
+ "# Python 3 only:\n",
+ "if isinstance(x, int):\n",
+ " ...\n",
+ "\n",
+ "# Python 2 and 3: option 1\n",
+ "from builtins import int # subclass of long on Py2\n",
+ "\n",
+ "if isinstance(x, int): # matches both int and long on Py2\n",
+ " ...\n",
+ "\n",
+ "# Python 2 and 3: option 2\n",
+ "from past.builtins import long\n",
+ "\n",
+ "if isinstance(x, (int, long)):\n",
+ " ..."
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### Octal constants"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "0644 # Python 2 only"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "0o644 # Python 2 and 3"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### Backtick repr"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "`x` # Python 2 only"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "repr(x) # Python 2 and 3"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### Metaclasses"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "class BaseForm(object):\n",
+ " pass\n",
+ "\n",
+ "class FormType(type):\n",
+ " pass"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "class Form(BaseForm):\n",
+ " __metaclass__ = FormType\n",
+ " pass"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 3 only:\n",
+ "class Form(BaseForm, metaclass=FormType):\n",
+ " pass"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3:\n",
+ "from six import with_metaclass\n",
+ "# or\n",
+ "from future.utils import with_metaclass\n",
+ "\n",
+ "class Form(with_metaclass(FormType, BaseForm)):\n",
+ " pass"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Strings and bytes"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### Unicode (text) string literals"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "If you are upgrading an existing Python 2 codebase, it may be preferable to mark up all string literals as unicode explicitly with ``u`` prefixes:"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only\n",
+ "s1 = 'The Zen of Python'\n",
+ "s2 = u'きたないのよりきれいな方がいい\\n'\n",
+ "\n",
+ "# Python 2 and 3\n",
+ "s1 = u'The Zen of Python'\n",
+ "s2 = u'きたないのよりきれいな方がいい\\n'"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "The ``futurize`` and ``python-modernize`` tools do not currently offer an option to do this automatically."
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "If you are writing code for a new project or new codebase, you can use this idiom to make all string literals in a module unicode strings:"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3\n",
+ "from __future__ import unicode_literals # at top of module\n",
+ "\n",
+ "s1 = 'The Zen of Python'\n",
+ "s2 = 'きたないのよりきれいな方がいい\\n'"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "See http://python-future.org/unicode_literals.html for more discussion on which style to use."
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### Byte-string literals"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only\n",
+ "s = 'This must be a byte-string'\n",
+ "\n",
+ "# Python 2 and 3\n",
+ "s = b'This must be a byte-string'"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "To loop over a byte-string with possible high-bit characters, obtaining each character as a byte-string of length 1:"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "for bytechar in 'byte-string with high-bit chars like \\xf9':\n",
+ " ...\n",
+ "\n",
+ "# Python 3 only:\n",
+ "for myint in b'byte-string with high-bit chars like \\xf9':\n",
+ " bytechar = bytes([myint])\n",
+ "\n",
+ "# Python 2 and 3:\n",
+ "from builtins import bytes\n",
+ "for myint in bytes(b'byte-string with high-bit chars like \\xf9'):\n",
+ " bytechar = bytes([myint])"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "As an alternative, ``chr()`` and ``.encode('latin-1')`` can be used to convert an int into a 1-char byte string:"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 3 only:\n",
+ "for myint in b'byte-string with high-bit chars like \\xf9':\n",
+ " char = chr(myint) # returns a unicode string\n",
+ " bytechar = char.encode('latin-1')\n",
+ "\n",
+ "# Python 2 and 3:\n",
+ "from builtins import bytes, chr\n",
+ "for myint in bytes(b'byte-string with high-bit chars like \\xf9'):\n",
+ " char = chr(myint) # returns a unicode string\n",
+ " bytechar = char.encode('latin-1') # forces returning a byte str"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### basestring"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "a = u'abc'\n",
+ "b = 'def'\n",
+ "assert (isinstance(a, basestring) and isinstance(b, basestring))\n",
+ "\n",
+ "# Python 2 and 3: alternative 1\n",
+ "from past.builtins import basestring # pip install future\n",
+ "\n",
+ "a = u'abc'\n",
+ "b = b'def'\n",
+ "assert (isinstance(a, basestring) and isinstance(b, basestring))"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: alternative 2: refactor the code to avoid considering\n",
+ "# byte-strings as strings.\n",
+ "\n",
+ "from builtins import str\n",
+ "a = u'abc'\n",
+ "b = b'def'\n",
+ "c = b.decode()\n",
+ "assert isinstance(a, str) and isinstance(c, str)\n",
+ "# ..."
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### unicode"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "templates = [u\"blog/blog_post_detail_%s.html\" % unicode(slug)]"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: alternative 1\n",
+ "from builtins import str\n",
+ "templates = [u\"blog/blog_post_detail_%s.html\" % str(slug)]"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: alternative 2\n",
+ "from builtins import str as text\n",
+ "templates = [u\"blog/blog_post_detail_%s.html\" % text(slug)]"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### StringIO"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "from StringIO import StringIO\n",
+ "# or:\n",
+ "from cStringIO import StringIO\n",
+ "\n",
+ "# Python 2 and 3:\n",
+ "from io import BytesIO # for handling byte strings\n",
+ "from io import StringIO # for handling unicode strings"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Imports relative to a package"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "Suppose the package is:\n",
+ "\n",
+ " mypackage/\n",
+ " __init__.py\n",
+ " submodule1.py\n",
+ " submodule2.py\n",
+ " \n",
+ "and the code below is in ``submodule1.py``:"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only: \n",
+ "import submodule2"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3:\n",
+ "from . import submodule2"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3:\n",
+ "# To make Py2 code safer (more like Py3) by preventing\n",
+ "# implicit relative imports, you can also add this to the top:\n",
+ "from __future__ import absolute_import"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Dictionaries"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "heights = {'Fred': 175, 'Anne': 166, 'Joe': 192}"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### Iterating through ``dict`` keys/values/items"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "Iterable dict keys:"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "for key in heights.iterkeys():\n",
+ " ..."
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3:\n",
+ "for key in heights:\n",
+ " ..."
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "Iterable dict values:"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "for value in heights.itervalues():\n",
+ " ..."
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Idiomatic Python 3\n",
+ "for value in heights.values(): # extra memory overhead on Py2\n",
+ " ..."
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 8,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: option 1\n",
+ "from builtins import dict\n",
+ "\n",
+ "heights = dict(Fred=175, Anne=166, Joe=192)\n",
+ "for key in heights.values(): # efficient on Py2 and Py3\n",
+ " ..."
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: option 2\n",
+ "from future.utils import itervalues\n",
+ "# or\n",
+ "from six import itervalues\n",
+ "\n",
+ "for key in itervalues(heights):\n",
+ " ..."
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "Iterable dict items:"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "for (key, value) in heights.iteritems():\n",
+ " ..."
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: option 1\n",
+ "for (key, value) in heights.items(): # inefficient on Py2 \n",
+ " ..."
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: option 2\n",
+ "from future.utils import viewitems\n",
+ "\n",
+ "for (key, value) in viewitems(heights): # also behaves like a set\n",
+ " ..."
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: option 3\n",
+ "from future.utils import iteritems\n",
+ "# or\n",
+ "from six import iteritems\n",
+ "\n",
+ "for (key, value) in iteritems(heights):\n",
+ " ..."
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### dict keys/values/items as a list"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "dict keys as a list:"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "keylist = heights.keys()\n",
+ "assert isinstance(keylist, list)"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3:\n",
+ "keylist = list(heights)\n",
+ "assert isinstance(keylist, list)"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "dict values as a list:"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "heights = {'Fred': 175, 'Anne': 166, 'Joe': 192}\n",
+ "valuelist = heights.values()\n",
+ "assert isinstance(valuelist, list)"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: option 1\n",
+ "valuelist = list(heights.values()) # inefficient on Py2"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: option 2\n",
+ "from builtins import dict\n",
+ "\n",
+ "heights = dict(Fred=175, Anne=166, Joe=192)\n",
+ "valuelist = list(heights.values())"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: option 3\n",
+ "from future.utils import listvalues\n",
+ "\n",
+ "valuelist = listvalues(heights)"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: option 4\n",
+ "from future.utils import itervalues\n",
+ "# or\n",
+ "from six import itervalues\n",
+ "\n",
+ "valuelist = list(itervalues(heights))"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "dict items as a list:"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: option 1\n",
+ "itemlist = list(heights.items()) # inefficient on Py2"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: option 2\n",
+ "from future.utils import listitems\n",
+ "\n",
+ "itemlist = listitems(heights)"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: option 3\n",
+ "from future.utils import iteritems\n",
+ "# or\n",
+ "from six import iteritems\n",
+ "\n",
+ "itemlist = list(iteritems(heights))"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Custom class behaviour"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### Custom iterators"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only\n",
+ "class Upper(object):\n",
+ " def __init__(self, iterable):\n",
+ " self._iter = iter(iterable)\n",
+ " def next(self): # Py2-style\n",
+ " return self._iter.next().upper()\n",
+ " def __iter__(self):\n",
+ " return self\n",
+ "\n",
+ "itr = Upper('hello')\n",
+ "assert itr.next() == 'H' # Py2-style\n",
+ "assert list(itr) == list('ELLO')"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: option 1\n",
+ "from builtins import object\n",
+ "\n",
+ "class Upper(object):\n",
+ " def __init__(self, iterable):\n",
+ " self._iter = iter(iterable)\n",
+ " def __next__(self): # Py3-style iterator interface\n",
+ " return next(self._iter).upper() # builtin next() function calls\n",
+ " def __iter__(self):\n",
+ " return self\n",
+ "\n",
+ "itr = Upper('hello')\n",
+ "assert next(itr) == 'H' # compatible style\n",
+ "assert list(itr) == list('ELLO')"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: option 2\n",
+ "from future.utils import implements_iterator\n",
+ "\n",
+ "@implements_iterator\n",
+ "class Upper(object):\n",
+ " def __init__(self, iterable):\n",
+ " self._iter = iter(iterable)\n",
+ " def __next__(self): # Py3-style iterator interface\n",
+ " return next(self._iter).upper() # builtin next() function calls\n",
+ " def __iter__(self):\n",
+ " return self\n",
+ "\n",
+ "itr = Upper('hello')\n",
+ "assert next(itr) == 'H'\n",
+ "assert list(itr) == list('ELLO')"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### Custom ``__str__`` methods"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "class MyClass(object):\n",
+ " def __unicode__(self):\n",
+ " return 'Unicode string: \\u5b54\\u5b50'\n",
+ " def __str__(self):\n",
+ " return unicode(self).encode('utf-8')\n",
+ "\n",
+ "a = MyClass()\n",
+ "print(a) # prints encoded string"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 11,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [
+ {
+ "name": "stdout",
+ "output_type": "stream",
+ "text": [
+ "Unicode string: 孔子\n"
+ ]
+ }
+ ],
+ "source": [
+ "# Python 2 and 3:\n",
+ "from future.utils import python_2_unicode_compatible\n",
+ "\n",
+ "@python_2_unicode_compatible\n",
+ "class MyClass(object):\n",
+ " def __str__(self):\n",
+ " return u'Unicode string: \\u5b54\\u5b50'\n",
+ "\n",
+ "a = MyClass()\n",
+ "print(a) # prints string encoded as utf-8 on Py2"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### Custom ``__nonzero__`` vs ``__bool__`` method:"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "class AllOrNothing(object):\n",
+ " def __init__(self, l):\n",
+ " self.l = l\n",
+ " def __nonzero__(self):\n",
+ " return all(self.l)\n",
+ "\n",
+ "container = AllOrNothing([0, 100, 200])\n",
+ "assert not bool(container)"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3:\n",
+ "from builtins import object\n",
+ "\n",
+ "class AllOrNothing(object):\n",
+ " def __init__(self, l):\n",
+ " self.l = l\n",
+ " def __bool__(self):\n",
+ " return all(self.l)\n",
+ "\n",
+ "container = AllOrNothing([0, 100, 200])\n",
+ "assert not bool(container)"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Lists versus iterators"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### xrange"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "for i in xrange(10**8):\n",
+ " ..."
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: forward-compatible\n",
+ "from builtins import range\n",
+ "for i in range(10**8):\n",
+ " ..."
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: backward-compatible\n",
+ "from past.builtins import xrange\n",
+ "for i in xrange(10**8):\n",
+ " ..."
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### range"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only\n",
+ "mylist = range(5)\n",
+ "assert mylist == [0, 1, 2, 3, 4]"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: forward-compatible: option 1\n",
+ "mylist = list(range(5)) # copies memory on Py2\n",
+ "assert mylist == [0, 1, 2, 3, 4]"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: forward-compatible: option 2\n",
+ "from builtins import range\n",
+ "\n",
+ "mylist = list(range(5))\n",
+ "assert mylist == [0, 1, 2, 3, 4]"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: option 3\n",
+ "from future.utils import lrange\n",
+ "\n",
+ "mylist = lrange(5)\n",
+ "assert mylist == [0, 1, 2, 3, 4]"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: backward compatible\n",
+ "from past.builtins import range\n",
+ "\n",
+ "mylist = range(5)\n",
+ "assert mylist == [0, 1, 2, 3, 4]"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### map"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "mynewlist = map(f, myoldlist)\n",
+ "assert mynewlist == [f(x) for x in myoldlist]"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: option 1\n",
+ "# Idiomatic Py3, but inefficient on Py2\n",
+ "mynewlist = list(map(f, myoldlist))\n",
+ "assert mynewlist == [f(x) for x in myoldlist]"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: option 2\n",
+ "from builtins import map\n",
+ "\n",
+ "mynewlist = list(map(f, myoldlist))\n",
+ "assert mynewlist == [f(x) for x in myoldlist]"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: option 3\n",
+ "try:\n",
+ " from itertools import imap as map\n",
+ "except ImportError:\n",
+ " pass\n",
+ "\n",
+ "mynewlist = list(map(f, myoldlist)) # inefficient on Py2\n",
+ "assert mynewlist == [f(x) for x in myoldlist]"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: option 4\n",
+ "from future.utils import lmap\n",
+ "\n",
+ "mynewlist = lmap(f, myoldlist)\n",
+ "assert mynewlist == [f(x) for x in myoldlist]"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: option 5\n",
+ "from past.builtins import map\n",
+ "\n",
+ "mynewlist = map(f, myoldlist)\n",
+ "assert mynewlist == [f(x) for x in myoldlist]"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### imap"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "from itertools import imap\n",
+ "\n",
+ "myiter = imap(func, myoldlist)\n",
+ "assert isinstance(myiter, iter)"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 3 only:\n",
+ "myiter = map(func, myoldlist)\n",
+ "assert isinstance(myiter, iter)"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: option 1\n",
+ "from builtins import map\n",
+ "\n",
+ "myiter = map(func, myoldlist)\n",
+ "assert isinstance(myiter, iter)"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: option 2\n",
+ "try:\n",
+ " from itertools import imap as map\n",
+ "except ImportError:\n",
+ " pass\n",
+ "\n",
+ "myiter = map(func, myoldlist)\n",
+ "assert isinstance(myiter, iter)"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### zip, izip"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "As above with ``zip`` and ``itertools.izip``."
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### filter, ifilter"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "As above with ``filter`` and ``itertools.ifilter`` too."
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Other builtins"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### File IO with open()"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": true
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only\n",
+ "f = open('myfile.txt')\n",
+ "data = f.read() # as a byte string\n",
+ "text = data.decode('utf-8')\n",
+ "\n",
+ "# Python 2 and 3: alternative 1\n",
+ "from io import open\n",
+ "f = open('myfile.txt', 'rb')\n",
+ "data = f.read() # as bytes\n",
+ "text = data.decode('utf-8') # unicode, not bytes\n",
+ "\n",
+ "# Python 2 and 3: alternative 2\n",
+ "from io import open\n",
+ "f = open('myfile.txt', encoding='utf-8')\n",
+ "text = f.read() # unicode, not bytes"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### reduce()"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "assert reduce(lambda x, y: x+y, [1, 2, 3, 4, 5]) == 1+2+3+4+5"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3:\n",
+ "from functools import reduce\n",
+ "\n",
+ "assert reduce(lambda x, y: x+y, [1, 2, 3, 4, 5]) == 1+2+3+4+5"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### raw_input()"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "name = raw_input('What is your name? ')\n",
+ "assert isinstance(name, str) # native str"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3:\n",
+ "from builtins import input\n",
+ "\n",
+ "name = input('What is your name? ')\n",
+ "assert isinstance(name, str) # native str on Py2 and Py3"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### input()"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "input(\"Type something safe please: \")"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3\n",
+ "from builtins import input\n",
+ "eval(input(\"Type something safe please: \"))"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "Warning: using either of these is **unsafe** with untrusted input."
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### file()"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "f = file(pathname)"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3:\n",
+ "f = open(pathname)\n",
+ "\n",
+ "# But preferably, use this:\n",
+ "from io import open\n",
+ "f = open(pathname, 'rb') # if f.read() should return bytes\n",
+ "# or\n",
+ "f = open(pathname, 'rt') # if f.read() should return unicode text"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### exec"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": true
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "exec 'x = 10'\n",
+ "\n",
+ "# Python 2 and 3:\n",
+ "exec('x = 10')"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": true
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "g = globals()\n",
+ "exec 'x = 10' in g\n",
+ "\n",
+ "# Python 2 and 3:\n",
+ "g = globals()\n",
+ "exec('x = 10', g)"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": true
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "l = locals()\n",
+ "exec 'x = 10' in g, l\n",
+ "\n",
+ "# Python 2 and 3:\n",
+ "exec('x = 10', g, l)"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "But note that Py3's `exec()` is less powerful (and less dangerous) than Py2's `exec` statement."
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### execfile()"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "execfile('myfile.py')"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: alternative 1\n",
+ "from past.builtins import execfile\n",
+ "\n",
+ "execfile('myfile.py')"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: alternative 2\n",
+ "exec(compile(open('myfile.py').read()))\n",
+ "\n",
+ "# This can sometimes cause this:\n",
+ "# SyntaxError: function ... uses import * and bare exec ...\n",
+ "# See https://github.com/PythonCharmers/python-future/issues/37"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### unichr()"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "assert unichr(8364) == '€'"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 3 only:\n",
+ "assert chr(8364) == '€'"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3:\n",
+ "from builtins import chr\n",
+ "assert chr(8364) == '€'"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### intern()"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "intern('mystring')"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 3 only:\n",
+ "from sys import intern\n",
+ "intern('mystring')"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: alternative 1\n",
+ "from past.builtins import intern\n",
+ "intern('mystring')"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: alternative 2\n",
+ "from six.moves import intern\n",
+ "intern('mystring')"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: alternative 3\n",
+ "from future.standard_library import install_aliases\n",
+ "install_aliases()\n",
+ "from sys import intern\n",
+ "intern('mystring')"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: alternative 2\n",
+ "try:\n",
+ " from sys import intern\n",
+ "except ImportError:\n",
+ " pass\n",
+ "intern('mystring')"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### apply()"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "args = ('a', 'b')\n",
+ "kwargs = {'kwarg1': True}"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "apply(f, args, kwargs)"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: alternative 1\n",
+ "f(*args, **kwargs)"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: alternative 2\n",
+ "from past.builtins import apply\n",
+ "apply(f, args, kwargs)"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### chr()"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "assert chr(64) == b'@'\n",
+ "assert chr(200) == b'\\xc8'"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 3 only: option 1\n",
+ "assert chr(64).encode('latin-1') == b'@'\n",
+ "assert chr(0xc8).encode('latin-1') == b'\\xc8'"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: option 1\n",
+ "from builtins import chr\n",
+ "\n",
+ "assert chr(64).encode('latin-1') == b'@'\n",
+ "assert chr(0xc8).encode('latin-1') == b'\\xc8'"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 3 only: option 2\n",
+ "assert bytes([64]) == b'@'\n",
+ "assert bytes([0xc8]) == b'\\xc8'"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: option 2\n",
+ "from builtins import bytes\n",
+ "\n",
+ "assert bytes([64]) == b'@'\n",
+ "assert bytes([0xc8]) == b'\\xc8'"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### cmp()"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "assert cmp('a', 'b') < 0 and cmp('b', 'a') > 0 and cmp('c', 'c') == 0"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: alternative 1\n",
+ "from past.builtins import cmp\n",
+ "assert cmp('a', 'b') < 0 and cmp('b', 'a') > 0 and cmp('c', 'c') == 0"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: alternative 2\n",
+ "cmp = lambda(x, y): (x > y) - (x < y)\n",
+ "assert cmp('a', 'b') < 0 and cmp('b', 'a') > 0 and cmp('c', 'c') == 0"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### reload()"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "reload(mymodule)"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3\n",
+ "from imp import reload\n",
+ "reload(mymodule)"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Standard library"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### dbm modules"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only\n",
+ "import anydbm\n",
+ "import whichdb\n",
+ "import dbm\n",
+ "import dumbdbm\n",
+ "import gdbm\n",
+ "\n",
+ "# Python 2 and 3: alternative 1\n",
+ "from future import standard_library\n",
+ "standard_library.install_aliases()\n",
+ "\n",
+ "import dbm\n",
+ "import dbm.ndbm\n",
+ "import dbm.dumb\n",
+ "import dbm.gnu\n",
+ "\n",
+ "# Python 2 and 3: alternative 2\n",
+ "from future.moves import dbm\n",
+ "from future.moves.dbm import dumb\n",
+ "from future.moves.dbm import ndbm\n",
+ "from future.moves.dbm import gnu\n",
+ "\n",
+ "# Python 2 and 3: alternative 3\n",
+ "from six.moves import dbm_gnu\n",
+ "# (others not supported)"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### commands / subprocess modules"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only\n",
+ "from commands import getoutput, getstatusoutput\n",
+ "\n",
+ "# Python 2 and 3\n",
+ "from future import standard_library\n",
+ "standard_library.install_aliases()\n",
+ "\n",
+ "from subprocess import getoutput, getstatusoutput"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### subprocess.check_output()"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2.7 and above\n",
+ "from subprocess import check_output\n",
+ "\n",
+ "# Python 2.6 and above: alternative 1\n",
+ "from future.moves.subprocess import check_output\n",
+ "\n",
+ "# Python 2.6 and above: alternative 2\n",
+ "from future import standard_library\n",
+ "standard_library.install_aliases()\n",
+ "\n",
+ "from subprocess import check_output"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### collections: Counter, OrderedDict, ChainMap"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 6,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2.7 and above\n",
+ "from collections import Counter, OrderedDict, ChainMap\n",
+ "\n",
+ "# Python 2.6 and above: alternative 1\n",
+ "from future.backports import Counter, OrderedDict, ChainMap\n",
+ "\n",
+ "# Python 2.6 and above: alternative 2\n",
+ "from future import standard_library\n",
+ "standard_library.install_aliases()\n",
+ "\n",
+ "from collections import Counter, OrderedDict, ChainMap"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### StringIO module"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only\n",
+ "from StringIO import StringIO\n",
+ "from cStringIO import StringIO"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3\n",
+ "from io import BytesIO\n",
+ "# and refactor StringIO() calls to BytesIO() if passing byte-strings"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### http module"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "import httplib\n",
+ "import Cookie\n",
+ "import cookielib\n",
+ "import BaseHTTPServer\n",
+ "import SimpleHTTPServer\n",
+ "import CGIHttpServer\n",
+ "\n",
+ "# Python 2 and 3 (after ``pip install future``):\n",
+ "import http.client\n",
+ "import http.cookies\n",
+ "import http.cookiejar\n",
+ "import http.server"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### xmlrpc module"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "import DocXMLRPCServer\n",
+ "import SimpleXMLRPCServer\n",
+ "\n",
+ "# Python 2 and 3 (after ``pip install future``):\n",
+ "import xmlrpc.server"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "import xmlrpclib\n",
+ "\n",
+ "# Python 2 and 3 (after ``pip install future``):\n",
+ "import xmlrpc.client"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### html escaping and entities"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3:\n",
+ "from cgi import escape\n",
+ "\n",
+ "# Safer (Python 2 and 3, after ``pip install future``):\n",
+ "from html import escape\n",
+ "\n",
+ "# Python 2 only:\n",
+ "from htmlentitydefs import codepoint2name, entitydefs, name2codepoint\n",
+ "\n",
+ "# Python 2 and 3 (after ``pip install future``):\n",
+ "from html.entities import codepoint2name, entitydefs, name2codepoint"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### html parsing"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "from HTMLParser import HTMLParser\n",
+ "\n",
+ "# Python 2 and 3 (after ``pip install future``)\n",
+ "from html.parser import HTMLParser\n",
+ "\n",
+ "# Python 2 and 3 (alternative 2):\n",
+ "from future.moves.html.parser import HTMLParser"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### urllib module"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "``urllib`` is the hardest module to use from Python 2/3 compatible code. You may like to use Requests (http://python-requests.org) instead."
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "from urlparse import urlparse\n",
+ "from urllib import urlencode\n",
+ "from urllib2 import urlopen, Request, HTTPError"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 2,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 3 only:\n",
+ "from urllib.parse import urlparse, urlencode\n",
+ "from urllib.request import urlopen, Request\n",
+ "from urllib.error import HTTPError"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: easiest option\n",
+ "from future.standard_library import install_aliases\n",
+ "install_aliases()\n",
+ "\n",
+ "from urllib.parse import urlparse, urlencode\n",
+ "from urllib.request import urlopen, Request\n",
+ "from urllib.error import HTTPError"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: alternative 2\n",
+ "from future.standard_library import hooks\n",
+ "\n",
+ "with hooks():\n",
+ " from urllib.parse import urlparse, urlencode\n",
+ " from urllib.request import urlopen, Request\n",
+ " from urllib.error import HTTPError"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: alternative 3\n",
+ "from future.moves.urllib.parse import urlparse, urlencode\n",
+ "from future.moves.urllib.request import urlopen, Request\n",
+ "from future.moves.urllib.error import HTTPError\n",
+ "# or\n",
+ "from six.moves.urllib.parse import urlparse, urlencode\n",
+ "from six.moves.urllib.request import urlopen\n",
+ "from six.moves.urllib.error import HTTPError"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 and 3: alternative 4\n",
+ "try:\n",
+ " from urllib.parse import urlparse, urlencode\n",
+ " from urllib.request import urlopen, Request\n",
+ " from urllib.error import HTTPError\n",
+ "except ImportError:\n",
+ " from urlparse import urlparse\n",
+ " from urllib import urlencode\n",
+ " from urllib2 import urlopen, Request, HTTPError"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### Tkinter"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "import Tkinter\n",
+ "import Dialog\n",
+ "import FileDialog\n",
+ "import ScrolledText\n",
+ "import SimpleDialog\n",
+ "import Tix \n",
+ "import Tkconstants\n",
+ "import Tkdnd \n",
+ "import tkColorChooser\n",
+ "import tkCommonDialog\n",
+ "import tkFileDialog\n",
+ "import tkFont\n",
+ "import tkMessageBox\n",
+ "import tkSimpleDialog\n",
+ "import ttk\n",
+ "\n",
+ "# Python 2 and 3 (after ``pip install future``):\n",
+ "import tkinter\n",
+ "import tkinter.dialog\n",
+ "import tkinter.filedialog\n",
+ "import tkinter.scrolledtext\n",
+ "import tkinter.simpledialog\n",
+ "import tkinter.tix\n",
+ "import tkinter.constants\n",
+ "import tkinter.dnd\n",
+ "import tkinter.colorchooser\n",
+ "import tkinter.commondialog\n",
+ "import tkinter.filedialog\n",
+ "import tkinter.font\n",
+ "import tkinter.messagebox\n",
+ "import tkinter.simpledialog\n",
+ "import tkinter.ttk"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### socketserver"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "import SocketServer\n",
+ "\n",
+ "# Python 2 and 3 (after ``pip install future``):\n",
+ "import socketserver"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### copy_reg, copyreg"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "import copy_reg\n",
+ "\n",
+ "# Python 2 and 3 (after ``pip install future``):\n",
+ "import copyreg"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### configparser"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "from ConfigParser import ConfigParser\n",
+ "\n",
+ "# Python 2 and 3 (after ``pip install future``):\n",
+ "from configparser import ConfigParser"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### queue"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "from Queue import Queue, heapq, deque\n",
+ "\n",
+ "# Python 2 and 3 (after ``pip install future``):\n",
+ "from queue import Queue, heapq, deque"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### repr, reprlib"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "from repr import aRepr, repr\n",
+ "\n",
+ "# Python 2 and 3 (after ``pip install future``):\n",
+ "from reprlib import aRepr, repr"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### UserDict, UserList, UserString"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "from UserDict import UserDict\n",
+ "from UserList import UserList\n",
+ "from UserString import UserString\n",
+ "\n",
+ "# Python 3 only:\n",
+ "from collections import UserDict, UserList, UserString\n",
+ "\n",
+ "# Python 2 and 3: alternative 1\n",
+ "from future.moves.collections import UserDict, UserList, UserString\n",
+ "\n",
+ "# Python 2 and 3: alternative 2\n",
+ "from six.moves import UserDict, UserList, UserString\n",
+ "\n",
+ "# Python 2 and 3: alternative 3\n",
+ "from future.standard_library import install_aliases\n",
+ "install_aliases()\n",
+ "from collections import UserDict, UserList, UserString"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### itertools: filterfalse, zip_longest"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {
+ "collapsed": false
+ },
+ "outputs": [],
+ "source": [
+ "# Python 2 only:\n",
+ "from itertools import ifilterfalse, izip_longest\n",
+ "\n",
+ "# Python 3 only:\n",
+ "from itertools import filterfalse, zip_longest\n",
+ "\n",
+ "# Python 2 and 3: alternative 1\n",
+ "from future.moves.itertools import filterfalse, zip_longest\n",
+ "\n",
+ "# Python 2 and 3: alternative 2\n",
+ "from six.moves import filterfalse, zip_longest\n",
+ "\n",
+ "# Python 2 and 3: alternative 3\n",
+ "from future.standard_library import install_aliases\n",
+ "install_aliases()\n",
+ "from itertools import filterfalse, zip_longest"
+ ]
+ }
+ ],
+ "metadata": {
+ "kernelspec": {
+ "display_name": "Python 3",
+ "language": "python",
+ "name": "python3"
+ },
+ "language_info": {
+ "codemirror_mode": {
+ "name": "ipython",
+ "version": 3
+ },
+ "file_extension": ".py",
+ "mimetype": "text/x-python",
+ "name": "python",
+ "nbconvert_exporter": "python",
+ "pygments_lexer": "ipython3",
+ "version": "3.4.3"
+ }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}
generated by cgit v1.2.3 (git 2.39.1) at 2026-06-01 14:56:41 +0000