The upcoming version Plone 5.2 will support Plone 3, what does that mean for you? When should you start to use Python 3 in your new Plone projects? When and how should you migrate existing projects to Python 3? How do you migrate addons and your custom code? Drawing from the experience with the migration of Plone itself I'll answer all the questions that arise from moving to Python 3.

1. P L O N E P Y T H O N 3
PHILIP BAUER
♥

2. TEXT (WAS UNICODE IN PY2)
BYTE S (WAS STRING IN PY2)
STRING (BYTES IN PY2 / TEXT IN PY3)

3. BYTES ARE MEASURED IN
KILOS, STORED IN DISKS
AND TRANSFERED
THROUGH CABLES

4. SAY: TEXT & BYTES
NOT: UNICODE & STRING

5. U N I C O D E S A N D W I C H
B Y T E S | T E X T | B Y T E ST E X T

6. safe_text (safe_unicode)
safe_bytes (safe_encode)

7. s a f e _ n a t i v e s t r i n g
b y t e s i n p y 3
t e x t i n p y 3

8. >>> 'foo' == u'foo'
True
>>> 'foo' + u'foo'
u'foofoo'
>>> u'foo' + 'foo'
u'foofoo'
Python 2
IMPLICIT CONVERSION

9. >>> b'foo' == 'foo'
False
>>> 'foo' + b'foo'
TypeError: can only concatenate str (not
"bytes") to str
>>> b'foo' + 'foo'
TypeError: can't concat str to bytes
Python 3
IMPLICIT CONVERSION

10. >>> byte = b'huhu'
>>> byte
'huhu'
>>> byte.decode('utf8')
u'huhu'
>>> byte.encode('utf8')
'huhu'
Python 2: bytes
EXPLICIT CONVERSION

11. >>> byte = b'huhu'
>>> byte
b'huhu'
>>> byte.decode('utf8')
'huhu'
>>> byte.encode('utf8')
AttributeError: 'bytes' object has no
attribute 'encode'
Python 3: bytes
EXPLICIT CONVERSION

12. >>> text = u'foo'
>>> text
u'foo'
>>> text.encode('utf8')
'foo'
>>> text.decode('utf8')
u'foo'
Python 2: text
EXPLICIT CONVERSION

13. >>> text = 'foo'
>>> text
'foo'
>>> text.encode('utf8')
b'foo'
>>> text.decode('utf8')
AttributeError: 'str' object has no attribute
'decode'
Python 3: text
EXPLICIT CONVERSION

14. ITERATING IS WEIRD

15. >>> [i for i in 'huhu']
['h', 'u', 'h', 'u']
Python 2
ITERATING OVER BYTES

16. >>> [i for i in b'huhu']
[104, 117, 104, 117]
>>> [chr(i) for i in b'huhu']
['h', 'u', 'h', 'u']
>>> [chr(i).encode('utf8') for i in b'huhu']
[b'h', b'u', b'h', b'u']
Python 3
ITERATING OVER BYTES

17. P Y T H O N 3 . 3
• Py3: u'text'
• Py2: b'bytes'
• u'text' is text in py2 and py3
• b'bytes' is bytes in py2 and py3

18. • text/bytes is the main issue when migrating code
• It makes much more sense in py3
• Writing code that works in py2/py3 is not easy

19. L E T ' S TA L K A B O U T B R A Z I L

27. ZOPE 4

29. POR TING PLONE TO
PYTHON 3

31. 1. MIGRATE PACKAGES FLYING BLIND
• Tools: six, sixer and python-modernize
• Educated Guessing™
• Testing in Python 2

32. 2 . S TA R T U P A N D M A N U A L T E S T
• Fix what breaks
• Test features manually
• Nightly demo

33. 3 . A U T O M AT E D T E S T S
• Get > 10.000 tests to work on Python 3
• Hunt & kill test-isolation issues
• doctests oh my

35. CURRENT STATE (DEMO)

36. THANK YOU TO ALL
THAT HELPED

37. STEFFEN ALLNER | PHILIP BAUER | ROEL
BRUGGINK | GODEFROID CHAPELLE | MAIK
DERSTAPPEN | GIL FORCADA | HARALD
FRISENEGGER | DAVID GLICK | DANIEL
HAVLIK | MICHAEL HOWITZ | JENS KLEIN |
DAVI LIMA | ALEXANDER LOECHEL |
THOMAS LOTZE | PETER MATHIS | JAN
MEVISSEN | ROBERT NIEDERREITER | JONI
ORPONEN | ALESSANDRO PISA | JOHANNES
RAGGAM | MAURITS VAN REES | MANUEL
REINHARDT | THOMAS SCHORR | ERIC
STEELE | JENS VAGELPOHL | MATTHEW
WILKES | ANDI ZEIDLER

46. UPGRADE TO PYTHON 3

47. 6 STEP PROCESS

48. 1 . U P G R A D E T O P L O N E 5 . 2
• Use Python 2.7

49. 2 . D R O P A R C H E T Y P E S
• It's not asking too much
• Migration for default types is available since 2013
• Migration for custom types is available since 2015

50. 3 . M I G R AT E Y O U R C O D E T O P Y T H O N 3
• Without Database
• Support Python 2 and Python 3
• Small addons: Startup and fix whatever fails
• Bigger addons: Use python-modernize
• Same with tests
• Beware of complex doctests

51. 4 . M I G R AT E A D D O N S
• Same as above
• Everyone benefits

52. 5 . M I G R AT E Y O U R D ATA B A S E
• See David Glick's Talk
• Downtime/Read-only might be ineviable

53. 6 . D E P L O Y O N P Y T H O N 3
• Test the production-setup with WSGI early

54. STAR T NOW
DON'T WAIT
WORK ITERATIVELY

55. R O A D M A P
• 5.2a1 now
• 5.2 final in February

56. T O D O
• FTP and/or WebDAV
• DB Migration
• Upgrade- and porting-guide
• Migrate Addons
• Performance-tests

57. COME TO THE SPRINT

58. BRING YOUR ADDONS

59. QUESTIONS

60. WHAT ABOUT PYTHON 4?

61. W H E N W I L L P L O N E D R O P
S U P P O R T F O R P Y T H O N 2 ?

62. WHAT ABOUT ZOPE 5?

63. WILL ARCHETYPES BE
POR TED TO PYTHON 3?

64. HOW DO WE REPLACE
FTP/WEBDAV?

65. W H Y D I D Y O U N O T ' S I M P LY '
M I G R AT E T O G U I L L I O T I N A ?

66. CAN I NOW USE ASYNC/
AWAIT?

67. W H Y D O E S N ' T T H E P L O N E
F O U N D AT I O N S I M P LY B U Y
S U P P O R T F O R P Y T H O N 2 . 7 F R O M
R E D H AT / I B M F O R A L L O F U S ?

68. DOES PYTHON 3 MAKE
PLONE RUN FASTER?

69. CAN I RUN THE SAME DB
IN PY2 AND PY3?

70. I S A D D O N < Y O U R N A M E H E R E >
A L R E A D Y P O R T E D ?

71. W I L L T H I S I N C R E A S E
P L O N E ' S M A R K E T S H A R E ?

72. HOW DO I DEPLOY INTO
PRODUCTION?

73. WILL THIS WORK ON
WINDOWS?

74. ARE PRODUCTION-TOOLS
ALREADY WORK, LIKE BACKUP,
ZRS OR RELSTORAGE?

75. DOES BOBTEMPLATES.PLONE AND
PLONECLI ALREADY WORK IN PY3?

76. MORE QUESTIONS...

77. @StarzelDe
pbauer
P L O N E P Y T H O N 3
PHILIP BAUER
♥
THANKS