Commit | Line | Data |
---|---|---|
86530b38 AT |
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="prev" href="global.html" /> | |
13 | <link rel="parent" href="simple.html" /> | |
14 | <link rel="next" href="compound.html" /> | |
15 | <meta name='aesop' content='information' /> | |
16 | <title>6.14 The exec statement </title> | |
17 | </head> | |
18 | <body> | |
19 | <DIV CLASS="navigation"> | |
20 | <div id='top-navigation-panel' xml:id='top-navigation-panel'> | |
21 | <table align="center" width="100%" cellpadding="0" cellspacing="2"> | |
22 | <tr> | |
23 | <td class='online-navigation'><a rel="prev" title="6.13 The global statement" | |
24 | href="global.html"><img src='../icons/previous.png' | |
25 | border='0' height='32' alt='Previous Page' width='32' /></A></td> | |
26 | <td class='online-navigation'><a rel="parent" title="6. Simple statements" | |
27 | href="simple.html"><img src='../icons/up.png' | |
28 | border='0' height='32' alt='Up One Level' width='32' /></A></td> | |
29 | <td class='online-navigation'><a rel="next" title="7. Compound statements" | |
30 | href="compound.html"><img src='../icons/next.png' | |
31 | border='0' height='32' alt='Next Page' width='32' /></A></td> | |
32 | <td align="center" width="100%">Python Reference Manual</td> | |
33 | <td class='online-navigation'><a rel="contents" title="Table of Contents" | |
34 | href="contents.html"><img src='../icons/contents.png' | |
35 | border='0' height='32' alt='Contents' width='32' /></A></td> | |
36 | <td class='online-navigation'><img src='../icons/blank.png' | |
37 | border='0' height='32' alt='' width='32' /></td> | |
38 | <td class='online-navigation'><a rel="index" title="Index" | |
39 | href="genindex.html"><img src='../icons/index.png' | |
40 | border='0' height='32' alt='Index' width='32' /></A></td> | |
41 | </tr></table> | |
42 | <div class='online-navigation'> | |
43 | <b class="navlabel">Previous:</b> | |
44 | <a class="sectref" rel="prev" href="global.html">6.13 The global statement</A> | |
45 | <b class="navlabel">Up:</b> | |
46 | <a class="sectref" rel="parent" href="simple.html">6. Simple statements</A> | |
47 | <b class="navlabel">Next:</b> | |
48 | <a class="sectref" rel="next" href="compound.html">7. Compound statements</A> | |
49 | </div> | |
50 | <hr /></div> | |
51 | </DIV> | |
52 | <!--End of Navigation Panel--> | |
53 | ||
54 | <H1><A NAME="SECTION0081400000000000000000"></A><A NAME="exec"></A> | |
55 | <BR> | |
56 | 6.14 The <tt class="keyword">exec</tt> statement | |
57 | </H1> | |
58 | <a id='l2h-563' xml:id='l2h-563'></a> | |
59 | <P> | |
60 | <dl><dd class="grammar"> | |
61 | <div class="productions"> | |
62 | <table> | |
63 | <tr> | |
64 | <td><a id='tok-exec_stmt' xml:id='tok-exec_stmt'>exec_stmt</a></td> | |
65 | <td>::=</td> | |
66 | <td>"exec" <a class='grammartoken' href="Booleans.html#tok-expression">expression</a> | |
67 | ["in" <a class='grammartoken' href="Booleans.html#tok-expression">expression</a> ["," <a class='grammartoken' href="Booleans.html#tok-expression">expression</a>]]</td></tr> | |
68 | </table> | |
69 | </div> | |
70 | <a class="grammar-footer" | |
71 | href="grammar.txt" type="text/plain" | |
72 | >Download entire grammar as text.</a> | |
73 | </dd></dl> | |
74 | ||
75 | <P> | |
76 | This statement supports dynamic execution of Python code. The first | |
77 | expression should evaluate to either a string, an open file object, or | |
78 | a code object. If it is a string, the string is parsed as a suite of | |
79 | Python statements which is then executed (unless a syntax error | |
80 | occurs). If it is an open file, the file is parsed until EOF and | |
81 | executed. If it is a code object, it is simply executed. In all | |
82 | cases, the code that's executed is expected to be be valid as file | |
83 | input (see section <A href="file-input.html#file-input">8.2</A>, ``File input''). Be aware that | |
84 | the <tt class="keyword">return</tt> and <tt class="keyword">yield</tt> statements may not be used | |
85 | outside of function definitions even within the context of code passed | |
86 | to the <tt class="keyword">exec</tt> statement. | |
87 | ||
88 | <P> | |
89 | In all cases, if the optional parts are omitted, the code is executed | |
90 | in the current scope. If only the first expression after <tt class="keyword">in</tt> | |
91 | is specified, it should be a dictionary, which will be used for both | |
92 | the global and the local variables. If two expressions are given, | |
93 | they are used for the global and local variables, respectively. | |
94 | If provided, <var>locals</var> can be any mapping object. | |
95 | ||
96 | <span class="versionnote">Changed in version 2.4: | |
97 | formerly <var>locals</var> was required to be a dictionary.</span> | |
98 | ||
99 | <P> | |
100 | As a side effect, an implementation may insert additional keys into | |
101 | the dictionaries given besides those corresponding to variable names | |
102 | set by the executed code. For example, the current implementation | |
103 | may add a reference to the dictionary of the built-in module | |
104 | <tt class="module">__builtin__</tt> under the key <code>__builtins__</code> (!). | |
105 | <a id='l2h-567' xml:id='l2h-567'></a> | |
106 | ||
107 | <P> | |
108 | <strong>Programmer's hints:</strong> | |
109 | dynamic evaluation of expressions is supported by the built-in | |
110 | function <tt class="function">eval()</tt>. The built-in functions | |
111 | <tt class="function">globals()</tt> and <tt class="function">locals()</tt> return the current global | |
112 | and local dictionary, respectively, which may be useful to pass around | |
113 | for use by <tt class="keyword">exec</tt>. | |
114 | <a id='l2h-564' xml:id='l2h-564'></a><a id='l2h-565' xml:id='l2h-565'></a><a id='l2h-566' xml:id='l2h-566'></a> | |
115 | <P> | |
116 | ||
117 | <DIV CLASS="navigation"> | |
118 | <div class='online-navigation'> | |
119 | <p></p><hr /> | |
120 | <table align="center" width="100%" cellpadding="0" cellspacing="2"> | |
121 | <tr> | |
122 | <td class='online-navigation'><a rel="prev" title="6.13 The global statement" | |
123 | href="global.html"><img src='../icons/previous.png' | |
124 | border='0' height='32' alt='Previous Page' width='32' /></A></td> | |
125 | <td class='online-navigation'><a rel="parent" title="6. Simple statements" | |
126 | href="simple.html"><img src='../icons/up.png' | |
127 | border='0' height='32' alt='Up One Level' width='32' /></A></td> | |
128 | <td class='online-navigation'><a rel="next" title="7. Compound statements" | |
129 | href="compound.html"><img src='../icons/next.png' | |
130 | border='0' height='32' alt='Next Page' width='32' /></A></td> | |
131 | <td align="center" width="100%">Python Reference Manual</td> | |
132 | <td class='online-navigation'><a rel="contents" title="Table of Contents" | |
133 | href="contents.html"><img src='../icons/contents.png' | |
134 | border='0' height='32' alt='Contents' width='32' /></A></td> | |
135 | <td class='online-navigation'><img src='../icons/blank.png' | |
136 | border='0' height='32' alt='' width='32' /></td> | |
137 | <td class='online-navigation'><a rel="index" title="Index" | |
138 | href="genindex.html"><img src='../icons/index.png' | |
139 | border='0' height='32' alt='Index' width='32' /></A></td> | |
140 | </tr></table> | |
141 | <div class='online-navigation'> | |
142 | <b class="navlabel">Previous:</b> | |
143 | <a class="sectref" rel="prev" href="global.html">6.13 The global statement</A> | |
144 | <b class="navlabel">Up:</b> | |
145 | <a class="sectref" rel="parent" href="simple.html">6. Simple statements</A> | |
146 | <b class="navlabel">Next:</b> | |
147 | <a class="sectref" rel="next" href="compound.html">7. Compound statements</A> | |
148 | </div> | |
149 | </div> | |
150 | <hr /> | |
151 | <span class="release-info">Release 2.4.2, documentation updated on 28 September 2005.</span> | |
152 | </DIV> | |
153 | <!--End of Navigation Panel--> | |
154 | <ADDRESS> | |
155 | See <i><a href="about.html">About this document...</a></i> for information on suggesting changes. | |
156 | </ADDRESS> | |
157 | </BODY> | |
158 | </HTML> |