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<title>7.8.1 Queue Objects</title>
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<H2><A NAME="SECTION009810000000000000000"></A>
<A NAME="QueueObjects"></A>
<BR>
7.8.1 Queue Objects
</H2>

<P>
Class <tt class="class">Queue</tt> implements queue objects and has the methods
described below.  This class can be derived from in order to implement
other queue organizations (e.g. stack) but the inheritable interface
is not described here.  See the source code for details.  The public
methods are:

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-2755' xml:id='l2h-2755' class="method">qsize</tt></b>(</nobr></td>
  <td><var></var>)</td></tr></table></dt>
<dd>
Return the approximate size of the queue.  Because of multithreading
semantics, this number is not reliable.
</dl>

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-2756' xml:id='l2h-2756' class="method">empty</tt></b>(</nobr></td>
  <td><var></var>)</td></tr></table></dt>
<dd>
Return <code>True</code> if the queue is empty, <code>False</code> otherwise.
Because of multithreading semantics, this is not reliable.
</dl>

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-2757' xml:id='l2h-2757' class="method">full</tt></b>(</nobr></td>
  <td><var></var>)</td></tr></table></dt>
<dd>
Return <code>True</code> if the queue is full, <code>False</code> otherwise.
Because of multithreading semantics, this is not reliable.
</dl>

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-2758' xml:id='l2h-2758' class="method">put</tt></b>(</nobr></td>
  <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>
<dd>
Put <var>item</var> into the queue. If optional args <var>block</var> is true
and <var>timeout</var> is None (the default), block if necessary until a
free slot is available. If <var>timeout</var> is a positive number, it
blocks at most <var>timeout</var> seconds and raises the <tt class="exception">Full</tt>
exception if no free slot was available within that time.
Otherwise (<var>block</var> is false), put an item on the queue if a free
slot is immediately available, else raise the <tt class="exception">Full</tt>
exception (<var>timeout</var> is ignored in that case).

<P>

<span class="versionnote">New in version 2.3:
the timeout parameter.</span>

<P>
</dl>

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-2759' xml:id='l2h-2759' class="method">put_nowait</tt></b>(</nobr></td>
  <td><var>item</var>)</td></tr></table></dt>
<dd>
Equivalent to <code>put(<var>item</var>, False)</code>.
</dl>

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-2760' xml:id='l2h-2760' class="method">get</tt></b>(</nobr></td>
  <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>
<dd>
Remove and return an item from the queue. If optional args
<var>block</var> is true and <var>timeout</var> is None (the default),
block if necessary until an item is available. If <var>timeout</var> is
a positive number, it blocks at most <var>timeout</var> seconds and raises
the <tt class="exception">Empty</tt> exception if no item was available within that
time. Otherwise (<var>block</var> is false), return an item if one is
immediately available, else raise the <tt class="exception">Empty</tt> exception
(<var>timeout</var> is ignored in that case).

<P>

<span class="versionnote">New in version 2.3:
the timeout parameter.</span>

<P>
</dl>

<P>
<dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline">
  <td><nobr><b><tt id='l2h-2761' xml:id='l2h-2761' class="method">get_nowait</tt></b>(</nobr></td>
  <td><var></var>)</td></tr></table></dt>
<dd>
Equivalent to <code>get(False)</code>.
</dl>

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<span class="release-info">Release 2.4.2, documentation updated on 28 September 2005.</span>
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