Introduction to Python

1. Python's Birth Xmas 1989

2. About two weeks of time off with no plans

3. Had it all in my head

4. Fat Mac with Lightspeed C on 20 MB hard drive

5. First code: a parser generator

6. Soon followed: a running program!

7. TIOBE Programming Community Index for March 2011 Position Mar 2011 Position Mar 2010 Programming Language Ratings Mar 2011 Delta Mar 2010 1 1 Java 19.711% +2.20% 2 2 C 15.262% -2.02% 3 4 C++ 8.754% -0.86% 4 6 C# 7.210% +2.95% 5 3 PHP 6.566% -3.34% 6 7 Python 5.737% +1.51% 7 5 (Visual) Basic 4.710% -1.86% 8 12 Objective-C 3.518% +1.55% 9 8 Perl 1.969% -1.85% 10 10 JavaScript 1.866% -0.78%

8. What is Python? O-O rapid prototyping language

9. Not just a scripting language

10. Not just another Perl

11. Easy to learn, read, use

12. Extensible (add new modules) C/C++/Fortran/whatever

13. Java (through Jython) Embeddable in applications

14. What is it used for? rapid prototyping

15. web programming (client and server side)

16. ad hoc programming ("scripting")

17. steering scientific applications

18. extension language

19. XML processing

20. database applications

21. GUI applications

22. education

23. Who is using it? Google (various projects)

24. NASA (several projects)

25. NYSE (one of only three languages "on the floor")

26. Industrial Light & Magic (everything)

27. Yahoo! (Yahoo mail & groups)

28. RealNetworks (function and load testing)

29. RedHat (Linux installation tools)

30. LLNL, Fermilab (steering scientific applications)

31. Zope Corporation (content management)

32. ObjectDomain (embedded Jython in UML tool)

33. Alice project at CMU (accessible 3D graphics)

34. More success stories at www.pythonology.com

35. Language properties Everything is an object

36. Packages, modules, classes, functions

37. Exception handling

38. Dynamic typing, polymorphism

39. Static scoping

40. Operator overloading

41. Indentation for block structure Otherwise conventional syntax

42. Compared to Perl Easier to learn very important for infrequent users More readable code

43. More maintainable code

44. Fewer “magical” side effects

45. More “safety” guarantees

46. Better Java integration

47. The Zen of Python Beautiful is better than ugly.

48. Explicit is better than implicit.

49. Simple is better than complex.

50. Complex is better than complicated.

51. Flat is better than nested.

52. Sparse is better than dense.

53. Readability counts.

54. Special cases aren't special enough to break the rules.

55. Although practicality beats purity.

56. Errors should never pass silently.

57. Unless explicitly silenced.

58. In the face of ambiguity, refuse the temptation to guess.

59. There should be one— and preferably only one —obvious way to do it.

60. Although that way may not be obvious at first unless you're Dutch.

61. Now is better than never.

62. Although never is often better than right now.

63. If the implementation is hard to explain, it's a bad idea.

64. If the implementation is easy to explain, it may be a good idea.

65. Namespaces are one honking great idea — let's do more of those! (a poem by Tim Peters)

66. Getting help http://python.org/

67. >>> help()

68. Indentation def foo(x): if x is not None and x == 0: bar() baz() else: qux(x) foo(x - 1)

69. Type hierarchy None, NotImplemented, Ellipsis

70. numbers.Number numbers.Integral Plain integers: -2147483648 ... 2147483647

71. Long integers

72. Booleans numbers.Real (float): double precision

73. numbers.Complex

74. Type hierarchy Sequences Immutable sequences Strings: “asdf”

75. Unicode: u”unicode asdf”

76. Tuples: 1, 2, 3 1, () Mutable sequences Lists: [1, 2, 3]

77. Byte Arrays: bytearray()

78. Type hierarchy Set types Sets: set()

79. Frozen sets: frozenset() Mappings Dictionaries: {'a': 1, 'b': 2}

80. Type hierarchy Callable types User-defined functions

81. User-defined methods

82. Generator functions

83. Built-in functions

84. Built-in methods

85. Class Types

86. Classic Classes

87. Class instances

88. Type hierarchy Classes

89. Class instances

90. Files

91. Internal types Code objects

92. Frame objects

93. Traceback objects

94. Slice objects

95. Static method objects

96. Class method objects

97. Control flow The if statement

98. if expression1 : … elif expression2 : … else: …

99. Control flow The while statement

100. while expression : … else: …

101. Control flow The for statement

102. for target_list in expression_list : … else: …

103. Function definitions def funcname ( param1, param2, param3=value, param4=value ): … funcname(1, 2) funcname(1, 2, 3, 4) funcname(1, 2, param4=4, param3=3) funcname(param4=1, param3=2, param2=3, param1=4)

104. Example function def gcd(a, b): "greatest common divisor" while a != 0: a, b = b%a, a # parallel assignment return b

105. Modules import re

106. from sys import stdout, stderr

107. from os import system as hack_them_all

108. Modules sys

109. os

110. re

111. struct

112. os.path

113. pickle, cPickle, shelve

114. socket, select, threading

Introduction to Python

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