Migrating from PHP to Python and Django

Many programmers cut their teeth with PHP before getting interested in Python. However, while the languages seem similar at first, there are many new concepts to grasp and a rich ecosystem of tools to master. This isn't easy, but with the right advice, a strong PHP developer can become an excellent Python developer very quickly.

Based on the experience of migrating a development team from PHP to Python and Django, this talk will examine how to tackle this journey. While the fundamental languages differences will be touched upon, this talk will focus on more interesting topics such as common python gotchas, tips for grokking Django, awesome tools and applications from the community, and how to manage such a migration for a large team of developers.

Transcript

1. Migrating from
   to
   and
   David Winterbottom
   @codeinthehole
   and
   

   View Slide

2. View Slide

3. •2010: In-house PHP framework
   •2012: Python, Django
   

   View Slide

4. Why?
   •General purpose language
   •Elegant, readable
   •BDFL
   

   View Slide

5. Today
   •Introduction to Python
   •Introduction to Django
   

   View Slide

6. View Slide

7. View Slide

8. Zen of python
   

   View Slide

9. View Slide

10. View Slide

11. View Slide

12. What’s
    http://www.davidshrigley.com/photo_htmpgs/lost_pidgeon.html
    

    View Slide

13. Cruft
    •Significant whitespace
    •() ; not required
    •Readability counts!
    

    View Slide

14. View Slide

15. View Slide

16. View Slide

17. Privacy
    •Nothing truly private
    •_name not in public API
    •__name mangled
    

    View Slide

18. switch () {}
    

    View Slide

19. View Slide

20. View Slide

21. OO
    •Type-hinting
    •Interfaces
    •Duck typing
    

    View Slide

22. View Slide

23. Don’t check type
    

    View Slide

24. Don’t check type
    

    View Slide

25. View Slide

26. View Slide

27. View Slide

28. Server set-up
    • Easy: apache2, mod_php
    • Tricky: apache2, mod_wsgi, ...
    • ...but getting better:
    • Servers: gunicorn, uWSGI
    • Platforms: ep.io, gondor.io
    

    View Slide

29. View Slide

30. >>> dir()
    ['__builtins__', '__doc__', '__name__', '__package__']
    >>> dir(__builtins__)
    ['ArithmeticError', 'AssertionError', 'AttributeError', 'BaseException', 'BufferError', 'BytesWarning',
    'DeprecationWarning', 'EOFError', 'Ellipsis', 'EnvironmentError', 'Exception', 'False', 'FloatingPointError',
    'FutureWarning', 'GeneratorExit', 'IOError', 'ImportError', 'ImportWarning', 'IndentationError', 'IndexError',
    'KeyError', 'KeyboardInterrupt', 'LookupError', 'MemoryError', 'NameError', 'None', 'NotImplemented',
    'NotImplementedError', 'OSError', 'OverflowError', 'PendingDeprecationWarning', 'ReferenceError', 'RuntimeError',
    'RuntimeWarning', 'StandardError', 'StopIteration', 'SyntaxError', 'SyntaxWarning', 'SystemError', 'SystemExit',
    'TabError', 'True', 'TypeError', 'UnboundLocalError', 'UnicodeDecodeError', 'UnicodeEncodeError', 'UnicodeError',
    'UnicodeTranslateError', 'UnicodeWarning', 'UserWarning', 'ValueError', 'Warning', 'ZeroDivisionError', '_',
    '__debug__', '__doc__', '__import__', '__name__', '__package__', 'abs', 'all', 'any', 'apply', 'basestring', 'bin',
    'bool', 'buffer', 'bytearray', 'bytes', 'callable', 'chr', 'classmethod', 'cmp', 'coerce', 'compile', 'complex',
    'copyright', 'credits', 'delattr', 'dict', 'dir', 'divmod', 'enumerate', 'eval', 'execfile', 'exit', 'file',
    'filter', 'float', 'format', 'frozenset', 'getattr', 'globals', 'hasattr', 'hash', 'help', 'hex', 'id', 'input',
    'int', 'intern', 'isinstance', 'issubclass', 'iter', 'len', 'license', 'list', 'locals', 'long', 'map', 'max',
    'memoryview', 'min', 'next', 'object', 'oct', 'open', 'ord', 'pow', 'print', 'property', 'quit', 'range',
    'raw_input', 'reduce', 'reload', 'repr', 'reversed', 'round', 'set', 'setattr', 'slice', 'sorted', 'staticmethod',
    'str', 'sum', 'super', 'tuple', 'type', 'unichr', 'unicode', 'vars', 'xrange', 'zip']
    built-ins
    

    View Slide

31. >>> dir()
    ['__builtins__', '__doc__', '__name__', '__package__']
    >>> dir(__builtins__)
    ['ArithmeticError', 'AssertionError', 'AttributeError', 'BaseException', 'BufferError', 'BytesWarning',
    'DeprecationWarning', 'EOFError', 'Ellipsis', 'EnvironmentError', 'Exception', 'False', 'FloatingPointError',
    'FutureWarning', 'GeneratorExit', 'IOError', 'ImportError', 'ImportWarning', 'IndentationError', 'IndexError',
    'KeyError', 'KeyboardInterrupt', 'LookupError', 'MemoryError', 'NameError', 'None', 'NotImplemented',
    'NotImplementedError', 'OSError', 'OverflowError', 'PendingDeprecationWarning', 'ReferenceError', 'RuntimeError',
    'RuntimeWarning', 'StandardError', 'StopIteration', 'SyntaxError', 'SyntaxWarning', 'SystemError', 'SystemExit',
    'TabError', 'True', 'TypeError', 'UnboundLocalError', 'UnicodeDecodeError', 'UnicodeEncodeError', 'UnicodeError',
    'UnicodeTranslateError', 'UnicodeWarning', 'UserWarning', 'ValueError', 'Warning', 'ZeroDivisionError', '_',
    '__debug__', '__doc__', '__import__', '__name__', '__package__', 'abs', 'all', 'any', 'apply', 'basestring', 'bin',
    'bool', 'buffer', 'bytearray', 'bytes', 'callable', 'chr', 'classmethod', 'cmp', 'coerce', 'compile', 'complex',
    'copyright', 'credits', 'delattr', 'dict', 'dir', 'divmod', 'enumerate', 'eval', 'execfile', 'exit', 'file',
    'filter', 'float', 'format', 'frozenset', 'getattr', 'globals', 'hasattr', 'hash', 'help', 'hex', 'id', 'input',
    'int', 'intern', 'isinstance', 'issubclass', 'iter', 'len', 'license', 'list', 'locals', 'long', 'map', 'max',
    'memoryview', 'min', 'next', 'object', 'oct', 'open', 'ord', 'pow', 'print', 'property', 'quit', 'range',
    'raw_input', 'reduce', 'reload', 'repr', 'reversed', 'round', 'set', 'setattr', 'slice', 'sorted', 'staticmethod',
    'str', 'sum', 'super', 'tuple', 'type', 'unichr', 'unicode', 'vars', 'xrange', 'zip']
    built-ins
    

    View Slide

32. >>> dir()
    ['__builtins__', '__doc__', '__name__', '__package__']
    >>> dir(__builtins__)
    ['ArithmeticError', 'AssertionError', 'AttributeError', 'BaseException', 'BufferError', 'BytesWarning',
    'DeprecationWarning', 'EOFError', 'Ellipsis', 'EnvironmentError', 'Exception', 'False', 'FloatingPointError',
    'FutureWarning', 'GeneratorExit', 'IOError', 'ImportError', 'ImportWarning', 'IndentationError', 'IndexError',
    'KeyError', 'KeyboardInterrupt', 'LookupError', 'MemoryError', 'NameError', 'None', 'NotImplemented',
    'NotImplementedError', 'OSError', 'OverflowError', 'PendingDeprecationWarning', 'ReferenceError', 'RuntimeError',
    'RuntimeWarning', 'StandardError', 'StopIteration', 'SyntaxError', 'SyntaxWarning', 'SystemError', 'SystemExit',
    'TabError', 'True', 'TypeError', 'UnboundLocalError', 'UnicodeDecodeError', 'UnicodeEncodeError', 'UnicodeError',
    'UnicodeTranslateError', 'UnicodeWarning', 'UserWarning', 'ValueError', 'Warning', 'ZeroDivisionError', '_',
    '__debug__', '__doc__', '__import__', '__name__', '__package__', 'abs', 'all', 'any', 'apply', 'basestring', 'bin',
    'bool', 'buffer', 'bytearray', 'bytes', 'callable', 'chr', 'classmethod', 'cmp', 'coerce', 'compile', 'complex',
    'copyright', 'credits', 'delattr', 'dict', 'dir', 'divmod', 'enumerate', 'eval', 'execfile', 'exit', 'file',
    'filter', 'float', 'format', 'frozenset', 'getattr', 'globals', 'hasattr', 'hash', 'help', 'hex', 'id', 'input',
    'int', 'intern', 'isinstance', 'issubclass', 'iter', 'len', 'license', 'list', 'locals', 'long', 'map', 'max',
    'memoryview', 'min', 'next', 'object', 'oct', 'open', 'ord', 'pow', 'print', 'property', 'quit', 'range',
    'raw_input', 'reduce', 'reload', 'repr', 'reversed', 'round', 'set', 'setattr', 'slice', 'sorted', 'staticmethod',
    'str', 'sum', 'super', 'tuple', 'type', 'unichr', 'unicode', 'vars', 'xrange', 'zip']
    built-ins
    

    View Slide

33. View Slide

34. TypeError
    >>> 'hello' + 100
    Traceback (most recent call last):
    File "", line 1, in
    TypeError: cannot concatenate 'str' and 'int' objects
    >>>
    duck, dynamic, strong
    

    View Slide

35. TypeError
    >>> 'hello' + 100
    Traceback (most recent call last):
    File "", line 1, in
    TypeError: cannot concatenate 'str' and 'int' objects
    >>>
    duck, dynamic, strong
    

    View Slide

36. TypeError
    >>> 'hello' + 100
    Traceback (most recent call last):
    File "", line 1, in
    TypeError: cannot concatenate 'str' and 'int' objects
    >>>
    duck, dynamic, strong
    

    View Slide

37. TypeError
    >>> 'hello' + 100
    Traceback (most recent call last):
    File "", line 1, in
    TypeError: cannot concatenate 'str' and 'int' objects
    >>>
    duck, dynamic, strong
    

    View Slide

38. Data-structures
    •PHP: array()
    •tuple(), dict(), set(), list(), , ...
    •... deque(), defaultdict() -
    collections
    

    View Slide

39. Inheritance
    multiple inheritance
    

    View Slide

40. Modules!
    •Multiple classes per file
    •Static methods not needed
    

    View Slide

41. View Slide

42. integer division
    

    View Slide

43. integer division
    

    View Slide

44. integer division
    

    View Slide

45. integer division
    

    View Slide

46. mutable defaults
    

    View Slide

47. mutable defaults
    

    View Slide

48. mutable defaults
    

    View Slide

49. mutable defaults
    

    View Slide

50. names and objects
    

    View Slide

51. names and objects
    

    View Slide

52. names and objects
    

    View Slide

53. names and objects
    

    View Slide

54. Demo
    http://people.csail.mit.edu/pgbovine/python/tutor.html
    

    View Slide

55. class attributes
    

    View Slide

56. class attributes
    

    View Slide

57. class attributes
    

    View Slide

58. View Slide

59. Circular references
    •Misleading errors messages
    •Environment-specific
    •Divide and conquer
    

    View Slide

60. The good stuff
    

    View Slide

61. Interpreter
    console
    

    View Slide

62. ipython
    

    View Slide

63. pdb
    

    View Slide

64. pdb
    

    View Slide

65. pdb
    

    View Slide

66. pip
    

    View Slide

67. pip
    

    View Slide

68. pip
    

    View Slide

69. virtualenn
    •virtualenvwrapper
    •workon django
    virtualenv
    

    View Slide

70. Testing
    •unittest ~ JUnit
    •nose, mock, coverage,
    pyhamcrest, twill, lettuce,
    tox
    

    View Slide

71. View Slide

72. docs
    

    View Slide

73. server
    runserver
    

    View Slide

74. admin
    

    View Slide

75. class-based views
    

    View Slide

76. View Slide

77. 1. Placing the project's primary focus on
    the core domain and domain logic
    

    View Slide

78. 1. Placing the project's primary focus on
    the core domain and domain logic
    2. Basing complex design on a model
    

    View Slide

79. 1. Placing the project's primary focus on
    the core domain and domain logic
    2. Basing complex design on a model
    3. Developers and domain experts
    collaborate to iteratively improve the
    model
    

    View Slide

80. View Slide

81. Models
    •Capture the “conceptual heart
    of the domain”
    •DB schema generated for you
    •Foundation for application
    

    View Slide

82. “...where powerful new features unfold as
    corollaries to older features.”
    

    View Slide

83. Libraries
    

    View Slide

84. django-extensions
    •Various useful utilities
    •runserver_plus (demo)
    

    View Slide

85. south
    •Database schema migrations
    •Data migrations
    •Not a magic bullet though
    

    View Slide

86. debug-toolbar
    •Inspect SQL queries
    •Template contexts
    •Signals, logging, ...
    

    View Slide

87. Tips
    •Do a pure python project
    •Read top questions on Stack
    Overflow
    •Get your IDE set-up
    

    View Slide

88. Teams
    •Books
    •Pairing
    •Dojos and workshops
    

    View Slide

89. Summary
    

    View Slide

90. Python :)
    •Clean and readable
    •Low learning curve
    •Rich eco-system of tools
    and libraries
    

    View Slide

91. Python :(
    •No-one wants to go back
    •Harder to hire
    •Low-lowel hosting
    

    View Slide

92. Thanks
    

    View Slide