| 1 | <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> |
| 2 | <html> |
| 3 | <head> |
| 4 | <link rel="STYLESHEET" href="ref.css" type='text/css' /> |
| 5 | <link rel="SHORTCUT ICON" href="../icons/pyfav.png" type="image/png" /> |
| 6 | <link rel='start' href='../index.html' title='Python Documentation Index' /> |
| 7 | <link rel="first" href="ref.html" title='Python Reference Manual' /> |
| 8 | <link rel='contents' href='contents.html' title="Contents" /> |
| 9 | <link rel='index' href='genindex.html' title='Index' /> |
| 10 | <link rel='last' href='about.html' title='About this document...' /> |
| 11 | <link rel='help' href='about.html' title='About this document...' /> |
| 12 | <link rel="next" href="lexical.html" /> |
| 13 | <link rel="prev" href="contents.html" /> |
| 14 | <link rel="parent" href="ref.html" /> |
| 15 | <link rel="next" href="implementations.html" /> |
| 16 | <meta name='aesop' content='information' /> |
| 17 | <title>1. Introduction</title> |
| 18 | </head> |
| 19 | <body> |
| 20 | <DIV CLASS="navigation"> |
| 21 | <div id='top-navigation-panel' xml:id='top-navigation-panel'> |
| 22 | <table align="center" width="100%" cellpadding="0" cellspacing="2"> |
| 23 | <tr> |
| 24 | <td class='online-navigation'><a rel="prev" title="Contents" |
| 25 | href="contents.html"><img src='../icons/previous.png' |
| 26 | border='0' height='32' alt='Previous Page' width='32' /></A></td> |
| 27 | <td class='online-navigation'><a rel="parent" title="Python Reference Manual" |
| 28 | href="ref.html"><img src='../icons/up.png' |
| 29 | border='0' height='32' alt='Up One Level' width='32' /></A></td> |
| 30 | <td class='online-navigation'><a rel="next" title="1.1 Alternate Implementations" |
| 31 | href="implementations.html"><img src='../icons/next.png' |
| 32 | border='0' height='32' alt='Next Page' width='32' /></A></td> |
| 33 | <td align="center" width="100%">Python Reference Manual</td> |
| 34 | <td class='online-navigation'><a rel="contents" title="Table of Contents" |
| 35 | href="contents.html"><img src='../icons/contents.png' |
| 36 | border='0' height='32' alt='Contents' width='32' /></A></td> |
| 37 | <td class='online-navigation'><img src='../icons/blank.png' |
| 38 | border='0' height='32' alt='' width='32' /></td> |
| 39 | <td class='online-navigation'><a rel="index" title="Index" |
| 40 | href="genindex.html"><img src='../icons/index.png' |
| 41 | border='0' height='32' alt='Index' width='32' /></A></td> |
| 42 | </tr></table> |
| 43 | <div class='online-navigation'> |
| 44 | <b class="navlabel">Previous:</b> |
| 45 | <a class="sectref" rel="prev" href="contents.html">Contents</A> |
| 46 | <b class="navlabel">Up:</b> |
| 47 | <a class="sectref" rel="parent" href="ref.html">Python Reference Manual</A> |
| 48 | <b class="navlabel">Next:</b> |
| 49 | <a class="sectref" rel="next" href="implementations.html">1.1 Alternate Implementations</A> |
| 50 | </div> |
| 51 | <hr /></div> |
| 52 | </DIV> |
| 53 | <!--End of Navigation Panel--> |
| 54 | |
| 55 | <H1><A NAME="SECTION003000000000000000000"></A><A NAME="introduction"></A> |
| 56 | <BR> |
| 57 | 1. Introduction |
| 58 | </H1> |
| 59 | |
| 60 | <P> |
| 61 | This reference manual describes the Python programming language. |
| 62 | It is not intended as a tutorial. |
| 63 | |
| 64 | <P> |
| 65 | While I am trying to be as precise as possible, I chose to use English |
| 66 | rather than formal specifications for everything except syntax and |
| 67 | lexical analysis. This should make the document more understandable |
| 68 | to the average reader, but will leave room for ambiguities. |
| 69 | Consequently, if you were coming from Mars and tried to re-implement |
| 70 | Python from this document alone, you might have to guess things and in |
| 71 | fact you would probably end up implementing quite a different language. |
| 72 | On the other hand, if you are using |
| 73 | Python and wonder what the precise rules about a particular area of |
| 74 | the language are, you should definitely be able to find them here. |
| 75 | If you would like to see a more formal definition of the language, |
| 76 | maybe you could volunteer your time -- or invent a cloning machine |
| 77 | :-). |
| 78 | |
| 79 | <P> |
| 80 | It is dangerous to add too many implementation details to a language |
| 81 | reference document -- the implementation may change, and other |
| 82 | implementations of the same language may work differently. On the |
| 83 | other hand, there is currently only one Python implementation in |
| 84 | widespread use (although alternate implementations exist), and |
| 85 | its particular quirks are sometimes worth being mentioned, especially |
| 86 | where the implementation imposes additional limitations. Therefore, |
| 87 | you'll find short ``implementation notes'' sprinkled throughout the |
| 88 | text. |
| 89 | |
| 90 | <P> |
| 91 | Every Python implementation comes with a number of built-in and |
| 92 | standard modules. These are not documented here, but in the separate |
| 93 | <em class="citetitle"><a |
| 94 | href="../lib/lib.html" |
| 95 | title="Python Library Reference" |
| 96 | >Python Library Reference</a></em> document. A few |
| 97 | built-in modules are mentioned when they interact in a significant way |
| 98 | with the language definition. |
| 99 | |
| 100 | <P> |
| 101 | |
| 102 | <p><br /></p><hr class='online-navigation' /> |
| 103 | <div class='online-navigation'> |
| 104 | <!--Table of Child-Links--> |
| 105 | <A NAME="CHILD_LINKS"><STRONG>Subsections</STRONG></a> |
| 106 | |
| 107 | <UL CLASS="ChildLinks"> |
| 108 | <LI><A href="implementations.html">1.1 Alternate Implementations</a> |
| 109 | <LI><A href="notation.html">1.2 Notation</a> |
| 110 | </ul> |
| 111 | <!--End of Table of Child-Links--> |
| 112 | </div> |
| 113 | |
| 114 | <DIV CLASS="navigation"> |
| 115 | <div class='online-navigation'> |
| 116 | <p></p><hr /> |
| 117 | <table align="center" width="100%" cellpadding="0" cellspacing="2"> |
| 118 | <tr> |
| 119 | <td class='online-navigation'><a rel="prev" title="Contents" |
| 120 | href="contents.html"><img src='../icons/previous.png' |
| 121 | border='0' height='32' alt='Previous Page' width='32' /></A></td> |
| 122 | <td class='online-navigation'><a rel="parent" title="Python Reference Manual" |
| 123 | href="ref.html"><img src='../icons/up.png' |
| 124 | border='0' height='32' alt='Up One Level' width='32' /></A></td> |
| 125 | <td class='online-navigation'><a rel="next" title="1.1 Alternate Implementations" |
| 126 | href="implementations.html"><img src='../icons/next.png' |
| 127 | border='0' height='32' alt='Next Page' width='32' /></A></td> |
| 128 | <td align="center" width="100%">Python Reference Manual</td> |
| 129 | <td class='online-navigation'><a rel="contents" title="Table of Contents" |
| 130 | href="contents.html"><img src='../icons/contents.png' |
| 131 | border='0' height='32' alt='Contents' width='32' /></A></td> |
| 132 | <td class='online-navigation'><img src='../icons/blank.png' |
| 133 | border='0' height='32' alt='' width='32' /></td> |
| 134 | <td class='online-navigation'><a rel="index" title="Index" |
| 135 | href="genindex.html"><img src='../icons/index.png' |
| 136 | border='0' height='32' alt='Index' width='32' /></A></td> |
| 137 | </tr></table> |
| 138 | <div class='online-navigation'> |
| 139 | <b class="navlabel">Previous:</b> |
| 140 | <a class="sectref" rel="prev" href="contents.html">Contents</A> |
| 141 | <b class="navlabel">Up:</b> |
| 142 | <a class="sectref" rel="parent" href="ref.html">Python Reference Manual</A> |
| 143 | <b class="navlabel">Next:</b> |
| 144 | <a class="sectref" rel="next" href="implementations.html">1.1 Alternate Implementations</A> |
| 145 | </div> |
| 146 | </div> |
| 147 | <hr /> |
| 148 | <span class="release-info">Release 2.4.2, documentation updated on 28 September 2005.</span> |
| 149 | </DIV> |
| 150 | <!--End of Navigation Panel--> |
| 151 | <ADDRESS> |
| 152 | See <i><a href="about.html">About this document...</a></i> for information on suggesting changes. |
| 153 | </ADDRESS> |
| 154 | </BODY> |
| 155 | </HTML> |