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
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
8. Zen of python
12. What’s http://www.davidshrigley.com/photo_htmpgs/lost_pidgeon.html
13. Cruft •Significant whitespace •() ; not required •Readability counts!
17. Privacy •Nothing truly private •_name not in public API •__name mangled
18. switch () {}
21. OO •Type-hinting •Interfaces •Duck typing
23. Don’t check type
24. Don’t check type
28. Server set-up • Easy: apache2, mod_php • Tricky: apache2, mod_wsgi, ... • ...but getting better: • Servers: gunicorn, uWSGI • Platforms: ep.io, gondor.io
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
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
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
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
72. docs
73. server runserver
74. admin
75. class-based views
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
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