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<H2><A NAME="SECTION007240000000000000000"></A><A NAME="lists"></A>
<BR>
5.2.4 List displays
</H2>
<a id='l2h-344' xml:id='l2h-344'></a><a id='l2h-345' xml:id='l2h-345'></a>
<P>
A list display is a possibly empty series of expressions enclosed in
square brackets:

<P>
<dl><dd class="grammar">
<div class="productions">
<table>
<tr>
    <td><a id='tok-test' xml:id='tok-test'>test</a></td>
    <td>::=</td>
    <td><a class='grammartoken' href="Booleans.html#tok-and_test">and_test</a> ( "or" <a class='grammartoken' href="Booleans.html#tok-and_test">and_test</a> )*
              | <a class='grammartoken' href="lambdas.html#tok-lambda_form">lambda_form</a></td></tr>
  <tr>
    <td><a id='tok-testlist' xml:id='tok-testlist'>testlist</a></td>
    <td>::=</td>
    <td><a class='grammartoken' href="lists.html#tok-test">test</a> ( "," <a class='grammartoken' href="lists.html#tok-test">test</a> )* [ "," ]</td></tr>
  <tr>
    <td><a id='tok-list_display' xml:id='tok-list_display'>list_display</a></td>
    <td>::=</td>
    <td>"[" [<a class='grammartoken' href="lists.html#tok-listmaker">listmaker</a>] "]"</td></tr>
  <tr>
    <td><a id='tok-listmaker' xml:id='tok-listmaker'>listmaker</a></td>
    <td>::=</td>
    <td><a class='grammartoken' href="Booleans.html#tok-expression">expression</a> ( <a class='grammartoken' href="lists.html#tok-list_for">list_for</a>
              | ( "," <a class='grammartoken' href="Booleans.html#tok-expression">expression</a> )* [","] )</td></tr>
  <tr>
    <td><a id='tok-list_iter' xml:id='tok-list_iter'>list_iter</a></td>
    <td>::=</td>
    <td><a class='grammartoken' href="lists.html#tok-list_for">list_for</a> | <a class='grammartoken' href="lists.html#tok-list_if">list_if</a></td></tr>
  <tr>
    <td><a id='tok-list_for' xml:id='tok-list_for'>list_for</a></td>
    <td>::=</td>
    <td>"for" <a class='grammartoken' href="exprlists.html#tok-expression_list">expression_list</a> "in" <a class='grammartoken' href="lists.html#tok-testlist">testlist</a>
              [<a class='grammartoken' href="lists.html#tok-list_iter">list_iter</a>]</td></tr>
  <tr>
    <td><a id='tok-list_if' xml:id='tok-list_if'>list_if</a></td>
    <td>::=</td>
    <td>"if" <a class='grammartoken' href="lists.html#tok-test">test</a> [<a class='grammartoken' href="lists.html#tok-list_iter">list_iter</a>]</td></tr>
</table>
</div>
<a class="grammar-footer"
  href="grammar.txt" type="text/plain"
  >Download entire grammar as text.</a>
</dd></dl>

<P>
A list display yields a new list object.  Its contents are specified
by providing either a list of expressions or a list comprehension.
<a id='l2h-346' xml:id='l2h-346'></a>When a comma-separated list of expressions is supplied, its elements are
evaluated from left to right and placed into the list object in that
order.  When a list comprehension is supplied, it consists of a
single expression followed by at least one <tt class="keyword">for</tt> clause and zero or
more <tt class="keyword">for</tt> or <tt class="keyword">if</tt> clauses.  In this
case, the elements of the new list are those that would be produced
by considering each of the <tt class="keyword">for</tt> or <tt class="keyword">if</tt> clauses a block,
nesting from
left to right, and evaluating the expression to produce a list element
each time the innermost block is reached<A NAME="tex2html4"
  HREF="#foot4516"><SUP>5.1</SUP></A>.
<a id='l2h-347' xml:id='l2h-347'></a><a id='l2h-348' xml:id='l2h-348'></a>
<P>
<BR><HR><H4>Footnotes</H4>
<DL>
<DT><A NAME="foot4516">... reached</A><A
 href="lists.html#tex2html4"><SUP>5.1</SUP></A></DT>
<DD>In Python 2.3, a
list comprehension "leaks" the control variables of each
"<tt class="samp">for</tt>" it contains into the containing scope.  However, this
behavior is deprecated, and relying on it will not work once this
bug is fixed in a future release

</DD>
</DL>
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	17	<title>5.2.4 List displays</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">
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	54
	55	<H2><A NAME="SECTION007240000000000000000"></A><A NAME="lists"></A>
	56	<BR>
	57	5.2.4 List displays
	58	</H2>
	59	<a id='l2h-344' xml:id='l2h-344'></a><a id='l2h-345' xml:id='l2h-345'></a>
	60	<P>
	61	A list display is a possibly empty series of expressions enclosed in
	62	square brackets:
	63
	64	<P>
65	<dl><dd class="grammar">
66	<div class="productions">
67	<table>
68	<tr>
69	<td><a id='tok-test' xml:id='tok-test'>test</a></td>
70	<td>::=</td>
71	<td><a class='grammartoken' href="Booleans.html#tok-and_test">and_test</a> ( "or" <a class='grammartoken' href="Booleans.html#tok-and_test">and_test</a> )*
72	\| <a class='grammartoken' href="lambdas.html#tok-lambda_form">lambda_form</a></td></tr>
73	<tr>
74	<td><a id='tok-testlist' xml:id='tok-testlist'>testlist</a></td>
75	<td>::=</td>
76	<td><a class='grammartoken' href="lists.html#tok-test">test</a> ( "," <a class='grammartoken' href="lists.html#tok-test">test</a> )* [ "," ]</td></tr>
77	<tr>
78	<td><a id='tok-list_display' xml:id='tok-list_display'>list_display</a></td>
79	<td>::=</td>
80	<td>"[" [<a class='grammartoken' href="lists.html#tok-listmaker">listmaker</a>] "]"</td></tr>
81	<tr>
82	<td><a id='tok-listmaker' xml:id='tok-listmaker'>listmaker</a></td>
83	<td>::=</td>
84	<td><a class='grammartoken' href="Booleans.html#tok-expression">expression</a> ( <a class='grammartoken' href="lists.html#tok-list_for">list_for</a>
85	\| ( "," <a class='grammartoken' href="Booleans.html#tok-expression">expression</a> )* [","] )</td></tr>
86	<tr>
87	<td><a id='tok-list_iter' xml:id='tok-list_iter'>list_iter</a></td>
88	<td>::=</td>
89	<td><a class='grammartoken' href="lists.html#tok-list_for">list_for</a> \| <a class='grammartoken' href="lists.html#tok-list_if">list_if</a></td></tr>
90	<tr>
91	<td><a id='tok-list_for' xml:id='tok-list_for'>list_for</a></td>
92	<td>::=</td>
93	<td>"for" <a class='grammartoken' href="exprlists.html#tok-expression_list">expression_list</a> "in" <a class='grammartoken' href="lists.html#tok-testlist">testlist</a>
94	[<a class='grammartoken' href="lists.html#tok-list_iter">list_iter</a>]</td></tr>
95	<tr>
96	<td><a id='tok-list_if' xml:id='tok-list_if'>list_if</a></td>
97	<td>::=</td>
98	<td>"if" <a class='grammartoken' href="lists.html#tok-test">test</a> [<a class='grammartoken' href="lists.html#tok-list_iter">list_iter</a>]</td></tr>
99	</table>
100	</div>
101	<a class="grammar-footer"
102	href="grammar.txt" type="text/plain"
103	>Download entire grammar as text.</a>
104	</dd></dl>
105
106	<P>
107	A list display yields a new list object. Its contents are specified
108	by providing either a list of expressions or a list comprehension.
109	<a id='l2h-346' xml:id='l2h-346'></a>When a comma-separated list of expressions is supplied, its elements are
110	evaluated from left to right and placed into the list object in that
111	order. When a list comprehension is supplied, it consists of a
112	single expression followed by at least one <tt class="keyword">for</tt> clause and zero or
113	more <tt class="keyword">for</tt> or <tt class="keyword">if</tt> clauses. In this
114	case, the elements of the new list are those that would be produced
115	by considering each of the <tt class="keyword">for</tt> or <tt class="keyword">if</tt> clauses a block,
116	nesting from
117	left to right, and evaluating the expression to produce a list element
118	each time the innermost block is reached<A NAME="tex2html4"
119	HREF="#foot4516"><SUP>5.1</SUP></A>.
120	<a id='l2h-347' xml:id='l2h-347'></a><a id='l2h-348' xml:id='l2h-348'></a>
121	<P>
122	<BR><HR><H4>Footnotes</H4>
123	<DL>
124	<DT><A NAME="foot4516">... reached</A><A
125	href="lists.html#tex2html4"><SUP>5.1</SUP></A></DT>
126	<DD>In Python 2.3, a
127	list comprehension "leaks" the control variables of each
128	"<tt class="samp">for</tt>" it contains into the containing scope. However, this
129	behavior is deprecated, and relying on it will not work once this
130	bug is fixed in a future release
131
132	</DD>
133	</DL>
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