Migrating from PHP to Python and Django

Transcript

1. Migrating from to and David Winterbottom @codeinthehole and

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

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

5. Today •Introduction to Python •Introduction to Django

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8. Zen of python

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

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

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

    mangled

18. switch () {}

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

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23. Don’t check type

24. Don’t check type

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28. Server set-up • Easy: apache2, mod_php • Tricky: apache2, mod_wsgi,

    ... • ...but getting better: • Servers: gunicorn, uWSGI • Platforms: ep.io, gondor.io
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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

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

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
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34. TypeError >>> 'hello' + 100 Traceback (most recent call last):

    File "<stdin>", line 1, in <module> TypeError: cannot concatenate 'str' and 'int' objects >>> duck, dynamic, strong

35. TypeError >>> 'hello' + 100 Traceback (most recent call last):

    File "<stdin>", line 1, in <module> TypeError: cannot concatenate 'str' and 'int' objects >>> duck, dynamic, strong

36. TypeError >>> 'hello' + 100 Traceback (most recent call last):

    File "<stdin>", line 1, in <module> TypeError: cannot concatenate 'str' and 'int' objects >>> duck, dynamic, strong

37. TypeError >>> 'hello' + 100 Traceback (most recent call last):

    File "<stdin>", line 1, in <module> TypeError: cannot concatenate 'str' and 'int' objects >>> duck, dynamic, strong

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

    deque(), defaultdict() - collections

39. Inheritance multiple inheritance

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

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42. integer division

43. integer division

44. integer division

45. integer division

46. mutable defaults

47. mutable defaults

48. mutable defaults

49. mutable defaults

50. names and objects

51. names and objects

52. names and objects

53. names and objects

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

55. class attributes

56. class attributes

57. class attributes

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

60. The good stuff

61. Interpreter console

62. ipython

63. pdb

64. pdb

65. pdb

66. pip

67. pip

68. pip

69. virtualenn •virtualenvwrapper •workon django virtualenv

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

    tox
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72. docs

73. server runserver

74. admin

75. class-based views

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

    and domain logic

78. 1. Placing the project's primary focus on the core domain

    and domain logic 2. Basing complex design on a model

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
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81. Models •Capture the “conceptual heart of the domain” •DB schema

    generated for you •Foundation for application

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

83. Libraries

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

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

    though

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

87. Tips •Do a pure python project •Read top questions on

    Stack Overflow •Get your IDE set-up

88. Teams •Books •Pairing •Dojos and workshops

89. Summary

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

    of tools and libraries

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

    •Low-lowel hosting

92. Thanks