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53 | ||
54 | <H2><A NAME="SECTION006110000000000000000"></A><A NAME="dynamic-features"></A> | |
55 | <BR> | |
56 | 4.1.1 Interaction with dynamic features | |
57 | </H2> | |
58 | ||
59 | <P> | |
60 | There are several cases where Python statements are illegal when | |
61 | used in conjunction with nested scopes that contain free | |
62 | variables. | |
63 | ||
64 | <P> | |
65 | If a variable is referenced in an enclosing scope, it is illegal | |
66 | to delete the name. An error will be reported at compile time. | |
67 | ||
68 | <P> | |
69 | If the wild card form of import -- "<tt class="samp">import *</tt>" -- is used in a | |
70 | function and the function contains or is a nested block with free | |
71 | variables, the compiler will raise a SyntaxError. | |
72 | ||
73 | <P> | |
74 | If <tt class="keyword">exec</tt> is used in a function and the function contains or | |
75 | is a nested block with free variables, the compiler will raise a | |
76 | <tt class="exception">SyntaxError</tt> unless the exec explicitly specifies the local | |
77 | namespace for the <tt class="keyword">exec</tt>. (In other words, "<tt class="samp">exec obj</tt>"would be illegal, but "<tt class="samp">exec obj in ns</tt>" would be legal.) | |
78 | ||
79 | <P> | |
80 | The <tt class="function">eval()</tt>, <tt class="function">execfile()</tt>, and <tt class="function">input()</tt> | |
81 | functions and the <tt class="keyword">exec</tt> statement do not have access to the | |
82 | full environment for resolving names. Names may be resolved in the | |
83 | local and global namespaces of the caller. Free variables are not | |
84 | resolved in the nearest enclosing namespace, but in the global | |
85 | namespace.<A NAME="tex2html3" | |
86 | HREF="#foot3527"><SUP>4.1</SUP></A>The <tt class="keyword">exec</tt> statement and the <tt class="function">eval()</tt> and | |
87 | <tt class="function">execfile()</tt> functions have optional arguments to override | |
88 | the global and local namespace. If only one namespace is specified, | |
89 | it is used for both. | |
90 | ||
91 | <P> | |
92 | <BR><HR><H4>Footnotes</H4> | |
93 | <DL> | |
94 | <DT><A NAME="foot3527">... | |
95 | namespace.</A><A | |
96 | href="dynamic-features.html#tex2html3"><SUP>4.1</SUP></A></DT> | |
97 | <DD>This limitation occurs because the code that is | |
98 | executed by these operations is not available at the time the | |
99 | module is compiled. | |
100 | ||
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137 | <span class="release-info">Release 2.4.2, documentation updated on 28 September 2005.</span> | |
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