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| 16 | <title>7.8.1 Queue Objects</title> |
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| 54 | <H2><A NAME="SECTION009810000000000000000"></A> |
| 55 | <A NAME="QueueObjects"></A> |
| 56 | <BR> |
| 57 | 7.8.1 Queue Objects |
| 58 | </H2> |
| 59 | |
| 60 | <P> |
| 61 | Class <tt class="class">Queue</tt> implements queue objects and has the methods |
| 62 | described below. This class can be derived from in order to implement |
| 63 | other queue organizations (e.g. stack) but the inheritable interface |
| 64 | is not described here. See the source code for details. The public |
| 65 | methods are: |
| 66 | |
| 67 | <P> |
| 68 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 69 | <td><nobr><b><tt id='l2h-2755' xml:id='l2h-2755' class="method">qsize</tt></b>(</nobr></td> |
| 70 | <td><var></var>)</td></tr></table></dt> |
| 71 | <dd> |
| 72 | Return the approximate size of the queue. Because of multithreading |
| 73 | semantics, this number is not reliable. |
| 74 | </dl> |
| 75 | |
| 76 | <P> |
| 77 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 78 | <td><nobr><b><tt id='l2h-2756' xml:id='l2h-2756' class="method">empty</tt></b>(</nobr></td> |
| 79 | <td><var></var>)</td></tr></table></dt> |
| 80 | <dd> |
| 81 | Return <code>True</code> if the queue is empty, <code>False</code> otherwise. |
| 82 | Because of multithreading semantics, this is not reliable. |
| 83 | </dl> |
| 84 | |
| 85 | <P> |
| 86 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 87 | <td><nobr><b><tt id='l2h-2757' xml:id='l2h-2757' class="method">full</tt></b>(</nobr></td> |
| 88 | <td><var></var>)</td></tr></table></dt> |
| 89 | <dd> |
| 90 | Return <code>True</code> if the queue is full, <code>False</code> otherwise. |
| 91 | Because of multithreading semantics, this is not reliable. |
| 92 | </dl> |
| 93 | |
| 94 | <P> |
| 95 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 96 | <td><nobr><b><tt id='l2h-2758' xml:id='l2h-2758' class="method">put</tt></b>(</nobr></td> |
| 97 | <td><var>item</var><big>[</big><var>, block</var><big>[</big><var>, timeout</var><big>]</big><var></var><big>]</big><var></var>)</td></tr></table></dt> |
| 98 | <dd> |
| 99 | Put <var>item</var> into the queue. If optional args <var>block</var> is true |
| 100 | and <var>timeout</var> is None (the default), block if necessary until a |
| 101 | free slot is available. If <var>timeout</var> is a positive number, it |
| 102 | blocks at most <var>timeout</var> seconds and raises the <tt class="exception">Full</tt> |
| 103 | exception if no free slot was available within that time. |
| 104 | Otherwise (<var>block</var> is false), put an item on the queue if a free |
| 105 | slot is immediately available, else raise the <tt class="exception">Full</tt> |
| 106 | exception (<var>timeout</var> is ignored in that case). |
| 107 | |
| 108 | <P> |
| 109 | |
| 110 | <span class="versionnote">New in version 2.3: |
| 111 | the timeout parameter.</span> |
| 112 | |
| 113 | <P> |
| 114 | </dl> |
| 115 | |
| 116 | <P> |
| 117 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 118 | <td><nobr><b><tt id='l2h-2759' xml:id='l2h-2759' class="method">put_nowait</tt></b>(</nobr></td> |
| 119 | <td><var>item</var>)</td></tr></table></dt> |
| 120 | <dd> |
| 121 | Equivalent to <code>put(<var>item</var>, False)</code>. |
| 122 | </dl> |
| 123 | |
| 124 | <P> |
| 125 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 126 | <td><nobr><b><tt id='l2h-2760' xml:id='l2h-2760' class="method">get</tt></b>(</nobr></td> |
| 127 | <td><var></var><big>[</big><var>block</var><big>[</big><var>, timeout</var><big>]</big><var></var><big>]</big><var></var>)</td></tr></table></dt> |
| 128 | <dd> |
| 129 | Remove and return an item from the queue. If optional args |
| 130 | <var>block</var> is true and <var>timeout</var> is None (the default), |
| 131 | block if necessary until an item is available. If <var>timeout</var> is |
| 132 | a positive number, it blocks at most <var>timeout</var> seconds and raises |
| 133 | the <tt class="exception">Empty</tt> exception if no item was available within that |
| 134 | time. Otherwise (<var>block</var> is false), return an item if one is |
| 135 | immediately available, else raise the <tt class="exception">Empty</tt> exception |
| 136 | (<var>timeout</var> is ignored in that case). |
| 137 | |
| 138 | <P> |
| 139 | |
| 140 | <span class="versionnote">New in version 2.3: |
| 141 | the timeout parameter.</span> |
| 142 | |
| 143 | <P> |
| 144 | </dl> |
| 145 | |
| 146 | <P> |
| 147 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> |
| 148 | <td><nobr><b><tt id='l2h-2761' xml:id='l2h-2761' class="method">get_nowait</tt></b>(</nobr></td> |
| 149 | <td><var></var>)</td></tr></table></dt> |
| 150 | <dd> |
| 151 | Equivalent to <code>get(False)</code>. |
| 152 | </dl> |
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