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  <div class="section" id="utility-registration-apis">
<h1>Utility Registration APIs<a class="headerlink" href="#utility-registration-apis" title="Permalink to this headline">¶</a></h1>
<p>Utilities are components that simply provide an interface. They are
instantiated at the time or before they are registered. Here we test the
simple query interface.</p>
<p>Before we register any utility, there is no utility available, of
course. The pure instatiation of an object does not make it a utility. If
you do not specify a default, you get a <cite>ComponentLookupError</cite>.</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">&gt;&gt;&gt; </span><span class="kn">from</span> <span class="nn">zope.component</span> <span class="kn">import</span> <span class="n">getUtility</span>
<span class="gp">&gt;&gt;&gt; </span><span class="kn">from</span> <span class="nn">zope.component</span> <span class="kn">import</span> <span class="n">queryUtility</span>
<span class="gp">&gt;&gt;&gt; </span><span class="kn">from</span> <span class="nn">zope.component.tests.examples</span> <span class="kn">import</span> <span class="n">I1</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">getUtility</span><span class="p">(</span><span class="n">I1</span><span class="p">)</span> 
<span class="gt">Traceback (most recent call last):</span>
<span class="c">...</span>
<span class="gr">ComponentLookupError</span>: <span class="n">\</span>
<span class="go">(&lt;InterfaceClass zope.component.tests.examples.I1&gt;, &#39;&#39;)</span>
</pre></div>
</div>
<p>Otherwise, you get the default:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">&gt;&gt;&gt; </span><span class="n">queryUtility</span><span class="p">(</span><span class="n">I1</span><span class="p">,</span> <span class="n">default</span><span class="o">=</span><span class="s">&#39;&lt;default&gt;&#39;</span><span class="p">)</span>
<span class="go">&#39;&lt;default&gt;&#39;</span>
</pre></div>
</div>
<p>Now we declare <cite>ob</cite> to be the utility providing <cite>I1</cite>:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">&gt;&gt;&gt; </span><span class="n">ob</span> <span class="o">=</span> <span class="nb">object</span><span class="p">()</span>
<span class="gp">&gt;&gt;&gt; </span><span class="kn">from</span> <span class="nn">zope.component</span> <span class="kn">import</span> <span class="n">getGlobalSiteManager</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">getGlobalSiteManager</span><span class="p">()</span><span class="o">.</span><span class="n">registerUtility</span><span class="p">(</span><span class="n">ob</span><span class="p">,</span> <span class="n">I1</span><span class="p">)</span>
</pre></div>
</div>
<p>Now the component is available:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">&gt;&gt;&gt; </span><span class="n">getUtility</span><span class="p">(</span><span class="n">I1</span><span class="p">)</span> <span class="ow">is</span> <span class="n">ob</span>
<span class="go">True</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">queryUtility</span><span class="p">(</span><span class="n">I1</span><span class="p">)</span> <span class="ow">is</span> <span class="n">ob</span>
<span class="go">True</span>
</pre></div>
</div>
<div class="section" id="named-utilities">
<h2>Named Utilities<a class="headerlink" href="#named-utilities" title="Permalink to this headline">¶</a></h2>
<p>Registering a utility without a name does not mean that it is available
when looking for the utility with a name:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">&gt;&gt;&gt; </span><span class="n">getUtility</span><span class="p">(</span><span class="n">I1</span><span class="p">,</span> <span class="n">name</span><span class="o">=</span><span class="s">&#39;foo&#39;</span><span class="p">)</span>
<span class="gt">Traceback (most recent call last):</span>
<span class="c">...</span>
<span class="gr">ComponentLookupError</span>:
<span class="go">(&lt;InterfaceClass zope.component.tests.examples.I1&gt;, &#39;foo&#39;)</span>

<span class="gp">&gt;&gt;&gt; </span><span class="n">queryUtility</span><span class="p">(</span><span class="n">I1</span><span class="p">,</span> <span class="n">name</span><span class="o">=</span><span class="s">&#39;foo&#39;</span><span class="p">,</span> <span class="n">default</span><span class="o">=</span><span class="s">&#39;&lt;default&gt;&#39;</span><span class="p">)</span>
<span class="go">&#39;&lt;default&gt;&#39;</span>
</pre></div>
</div>
<p>Registering the utility under the correct name makes it available:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">&gt;&gt;&gt; </span><span class="n">ob2</span> <span class="o">=</span> <span class="nb">object</span><span class="p">()</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">getGlobalSiteManager</span><span class="p">()</span><span class="o">.</span><span class="n">registerUtility</span><span class="p">(</span><span class="n">ob2</span><span class="p">,</span> <span class="n">I1</span><span class="p">,</span> <span class="n">name</span><span class="o">=</span><span class="s">&#39;foo&#39;</span><span class="p">)</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">getUtility</span><span class="p">(</span><span class="n">I1</span><span class="p">,</span> <span class="s">&#39;foo&#39;</span><span class="p">)</span> <span class="ow">is</span> <span class="n">ob2</span>
<span class="go">True</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">queryUtility</span><span class="p">(</span><span class="n">I1</span><span class="p">,</span> <span class="s">&#39;foo&#39;</span><span class="p">)</span> <span class="ow">is</span> <span class="n">ob2</span>
<span class="go">True</span>
</pre></div>
</div>
</div>
<div class="section" id="querying-multiple-utilities">
<h2>Querying Multiple Utilities<a class="headerlink" href="#querying-multiple-utilities" title="Permalink to this headline">¶</a></h2>
<p>Sometimes it may be useful to query all utilities, both anonymous and named
for a given interface.  The <tt class="xref py py-func docutils literal"><span class="pre">getUtilitiesFor()</span></tt> API
returns a sequence of <tt class="docutils literal"><span class="pre">(name,</span> <span class="pre">utility)</span></tt> tuples, where <tt class="docutils literal"><span class="pre">name</span></tt> is the
empty string for the anonymous utility:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">&gt;&gt;&gt; </span><span class="kn">from</span> <span class="nn">zope.component</span> <span class="kn">import</span> <span class="n">getUtilitiesFor</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">tuples</span> <span class="o">=</span> <span class="nb">list</span><span class="p">(</span><span class="n">getUtilitiesFor</span><span class="p">(</span><span class="n">I1</span><span class="p">))</span>
<span class="gp">&gt;&gt;&gt; </span><span class="nb">len</span><span class="p">(</span><span class="n">tuples</span><span class="p">)</span>
<span class="go">2</span>
<span class="gp">&gt;&gt;&gt; </span><span class="p">(</span><span class="s">&#39;&#39;</span><span class="p">,</span> <span class="n">ob</span><span class="p">)</span> <span class="ow">in</span> <span class="n">tuples</span>
<span class="go">True</span>
<span class="gp">&gt;&gt;&gt; </span><span class="p">(</span><span class="s">&#39;foo&#39;</span><span class="p">,</span> <span class="n">ob2</span><span class="p">)</span> <span class="ow">in</span> <span class="n">tuples</span>
<span class="go">True</span>
</pre></div>
</div>
<p>The <tt class="xref py py-func docutils literal"><span class="pre">getAllUtilitiesRegisteredFor()</span></tt> API returns
utilities that have been registered for a particular interface. Utilities
providing a derived interface are also listed.</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">&gt;&gt;&gt; </span><span class="kn">from</span> <span class="nn">zope.interface</span> <span class="kn">import</span> <span class="n">implementer</span>
<span class="gp">&gt;&gt;&gt; </span><span class="kn">from</span> <span class="nn">zope.component.tests.examples</span> <span class="kn">import</span> <span class="n">Comp</span>
<span class="gp">&gt;&gt;&gt; </span><span class="kn">from</span> <span class="nn">zope.component.tests.examples</span> <span class="kn">import</span> <span class="n">I2</span>
<span class="gp">&gt;&gt;&gt; </span><span class="kn">from</span> <span class="nn">zope.component.tests.examples</span> <span class="kn">import</span> <span class="n">Ob</span>
<span class="gp">&gt;&gt;&gt; </span><span class="k">class</span> <span class="nc">I11</span><span class="p">(</span><span class="n">I1</span><span class="p">):</span>
<span class="gp">... </span>    <span class="k">pass</span>

<span class="gp">&gt;&gt;&gt; </span><span class="nd">@implementer</span><span class="p">(</span><span class="n">I11</span><span class="p">)</span>
<span class="gp">... </span><span class="k">class</span> <span class="nc">Ob11</span><span class="p">(</span><span class="n">Ob</span><span class="p">):</span>
<span class="gp">... </span>    <span class="k">pass</span>

<span class="gp">&gt;&gt;&gt; </span><span class="n">ob11</span> <span class="o">=</span> <span class="n">Ob11</span><span class="p">()</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">ob_bob</span> <span class="o">=</span> <span class="n">Ob</span><span class="p">()</span>
</pre></div>
</div>
<p>Now we register the new utilities:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">&gt;&gt;&gt; </span><span class="kn">from</span> <span class="nn">zope.component</span> <span class="kn">import</span> <span class="n">getGlobalSiteManager</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">gsm</span> <span class="o">=</span> <span class="n">getGlobalSiteManager</span><span class="p">()</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">gsm</span><span class="o">.</span><span class="n">registerUtility</span><span class="p">(</span><span class="n">ob</span><span class="p">,</span> <span class="n">I1</span><span class="p">)</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">gsm</span><span class="o">.</span><span class="n">registerUtility</span><span class="p">(</span><span class="n">ob11</span><span class="p">,</span> <span class="n">I11</span><span class="p">)</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">gsm</span><span class="o">.</span><span class="n">registerUtility</span><span class="p">(</span><span class="n">ob_bob</span><span class="p">,</span> <span class="n">I1</span><span class="p">,</span> <span class="n">name</span><span class="o">=</span><span class="s">&#39;bob&#39;</span><span class="p">)</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">gsm</span><span class="o">.</span><span class="n">registerUtility</span><span class="p">(</span><span class="n">Comp</span><span class="p">(</span><span class="mi">2</span><span class="p">),</span> <span class="n">I2</span><span class="p">)</span>
</pre></div>
</div>
<p>We can now get all the utilities that provide interface <cite>I1</cite>:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">&gt;&gt;&gt; </span><span class="kn">from</span> <span class="nn">zope.component</span> <span class="kn">import</span> <span class="n">getAllUtilitiesRegisteredFor</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">uts</span> <span class="o">=</span> <span class="nb">list</span><span class="p">(</span><span class="n">getAllUtilitiesRegisteredFor</span><span class="p">(</span><span class="n">I1</span><span class="p">))</span>
<span class="gp">&gt;&gt;&gt; </span><span class="nb">len</span><span class="p">(</span><span class="n">uts</span><span class="p">)</span>
<span class="go">4</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">ob</span> <span class="ow">in</span> <span class="n">uts</span>
<span class="go">True</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">ob2</span> <span class="ow">in</span> <span class="n">uts</span>
<span class="go">True</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">ob_bob</span> <span class="ow">in</span> <span class="n">uts</span>
<span class="go">True</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">ob11</span> <span class="ow">in</span> <span class="n">uts</span>
<span class="go">True</span>
</pre></div>
</div>
<p>Note that <cite>getAllUtilitiesRegisteredFor()</cite> does not return the names of
the utilities.</p>
</div>
<div class="section" id="delegated-utility-lookup">
<h2>Delegated Utility Lookup<a class="headerlink" href="#delegated-utility-lookup" title="Permalink to this headline">¶</a></h2>
<p>It is common for a utility to delegate its answer to a utility
providing the same interface in one of the component registry&#8217;s
bases. Let&#8217;s first create a global utility:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">&gt;&gt;&gt; </span><span class="kn">from</span> <span class="nn">zope.interface</span> <span class="kn">import</span> <span class="n">Interface</span>
<span class="gp">&gt;&gt;&gt; </span><span class="kn">from</span> <span class="nn">zope.interface</span> <span class="kn">import</span> <span class="n">implementer</span>
<span class="gp">&gt;&gt;&gt; </span><span class="k">class</span> <span class="nc">IMyUtility</span><span class="p">(</span><span class="n">Interface</span><span class="p">):</span>
<span class="gp">... </span>    <span class="k">pass</span>

<span class="gp">&gt;&gt;&gt; </span><span class="kn">from</span> <span class="nn">zope.component.tests.examples</span> <span class="kn">import</span> <span class="n">ConformsToIComponentLookup</span>
<span class="gp">&gt;&gt;&gt; </span><span class="nd">@implementer</span><span class="p">(</span><span class="n">IMyUtility</span><span class="p">)</span>
<span class="gp">... </span><span class="k">class</span> <span class="nc">MyUtility</span><span class="p">(</span><span class="n">ConformsToIComponentLookup</span><span class="p">):</span>
<span class="gp">... </span>    <span class="k">def</span> <span class="nf">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="nb">id</span><span class="p">,</span> <span class="n">sm</span><span class="p">):</span>
<span class="gp">... </span>        <span class="bp">self</span><span class="o">.</span><span class="n">id</span> <span class="o">=</span> <span class="nb">id</span>
<span class="gp">... </span>        <span class="bp">self</span><span class="o">.</span><span class="n">sitemanager</span> <span class="o">=</span> <span class="n">sm</span>
<span class="gp">... </span>    <span class="k">def</span> <span class="nf">__repr__</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="gp">... </span>        <span class="k">return</span> <span class="s">&quot;</span><span class="si">%s</span><span class="s">(&#39;</span><span class="si">%s</span><span class="s">&#39;)&quot;</span> <span class="o">%</span> <span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">__class__</span><span class="o">.</span><span class="n">__name__</span><span class="p">,</span> <span class="bp">self</span><span class="o">.</span><span class="n">id</span><span class="p">)</span>

<span class="gp">&gt;&gt;&gt; </span><span class="n">gutil</span> <span class="o">=</span> <span class="n">MyUtility</span><span class="p">(</span><span class="s">&#39;global&#39;</span><span class="p">,</span> <span class="n">gsm</span><span class="p">)</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">gsm</span><span class="o">.</span><span class="n">registerUtility</span><span class="p">(</span><span class="n">gutil</span><span class="p">,</span> <span class="n">IMyUtility</span><span class="p">,</span> <span class="s">&#39;myutil&#39;</span><span class="p">)</span>
</pre></div>
</div>
<p>Now, let&#8217;s create two registries and set up the bases hierarchy:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">&gt;&gt;&gt; </span><span class="kn">from</span> <span class="nn">zope.interface.registry</span> <span class="kn">import</span> <span class="n">Components</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">sm1</span> <span class="o">=</span> <span class="n">Components</span><span class="p">(</span><span class="s">&#39;sm1&#39;</span><span class="p">,</span> <span class="n">bases</span><span class="o">=</span><span class="p">(</span><span class="n">gsm</span><span class="p">,</span> <span class="p">))</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">sm1_1</span> <span class="o">=</span> <span class="n">Components</span><span class="p">(</span><span class="s">&#39;sm1_1&#39;</span><span class="p">,</span> <span class="n">bases</span><span class="o">=</span><span class="p">(</span><span class="n">sm1</span><span class="p">,</span> <span class="p">))</span>
</pre></div>
</div>
<p>Now we create two utilities and insert them in our folder hierarchy:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">&gt;&gt;&gt; </span><span class="kn">from</span> <span class="nn">zope.component.interfaces</span> <span class="kn">import</span> <span class="n">IComponentLookup</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">util1</span> <span class="o">=</span> <span class="n">MyUtility</span><span class="p">(</span><span class="s">&#39;one&#39;</span><span class="p">,</span> <span class="n">sm1</span><span class="p">)</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">sm1</span><span class="o">.</span><span class="n">registerUtility</span><span class="p">(</span><span class="n">util1</span><span class="p">,</span> <span class="n">IMyUtility</span><span class="p">,</span> <span class="s">&#39;myutil&#39;</span><span class="p">)</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">IComponentLookup</span><span class="p">(</span><span class="n">util1</span><span class="p">)</span> <span class="ow">is</span> <span class="n">sm1</span>
<span class="go">True</span>

<span class="gp">&gt;&gt;&gt; </span><span class="n">util1_1</span> <span class="o">=</span> <span class="n">MyUtility</span><span class="p">(</span><span class="s">&#39;one-one&#39;</span><span class="p">,</span> <span class="n">sm1_1</span><span class="p">)</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">sm1_1</span><span class="o">.</span><span class="n">registerUtility</span><span class="p">(</span><span class="n">util1_1</span><span class="p">,</span> <span class="n">IMyUtility</span><span class="p">,</span> <span class="s">&#39;myutil&#39;</span><span class="p">)</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">IComponentLookup</span><span class="p">(</span><span class="n">util1_1</span><span class="p">)</span> <span class="ow">is</span> <span class="n">sm1_1</span>
<span class="go">True</span>
</pre></div>
</div>
<p>Now, if we ask <cite>util1_1</cite> for its next available utility we get the
<tt class="docutils literal"><span class="pre">one</span></tt> utility:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">&gt;&gt;&gt; </span><span class="kn">from</span> <span class="nn">zope.component</span> <span class="kn">import</span> <span class="n">getNextUtility</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">getNextUtility</span><span class="p">(</span><span class="n">util1_1</span><span class="p">,</span> <span class="n">IMyUtility</span><span class="p">,</span> <span class="s">&#39;myutil&#39;</span><span class="p">)</span>
<span class="go">MyUtility(&#39;one&#39;)</span>
</pre></div>
</div>
<p>Next we ask <cite>util1</cite> for its next utility and we should get the global version:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">&gt;&gt;&gt; </span><span class="n">getNextUtility</span><span class="p">(</span><span class="n">util1</span><span class="p">,</span> <span class="n">IMyUtility</span><span class="p">,</span> <span class="s">&#39;myutil&#39;</span><span class="p">)</span>
<span class="go">MyUtility(&#39;global&#39;)</span>
</pre></div>
</div>
<p>However, if we ask the global utility for the next one, an error is raised</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">&gt;&gt;&gt; </span><span class="n">getNextUtility</span><span class="p">(</span><span class="n">gutil</span><span class="p">,</span> <span class="n">IMyUtility</span><span class="p">,</span>
<span class="gp">... </span>                    <span class="s">&#39;myutil&#39;</span><span class="p">)</span> 
<span class="gt">Traceback (most recent call last):</span>
<span class="c">...</span>
<span class="gr">ComponentLookupError</span>:
<span class="go">No more utilities for &lt;InterfaceClass zope.component.tests.examples.IMyUtility&gt;,</span>
<span class="go">&#39;myutil&#39; have been found.</span>
</pre></div>
</div>
<p>You can also use <cite>queryNextUtility</cite> and specify a default:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">&gt;&gt;&gt; </span><span class="kn">from</span> <span class="nn">zope.component</span> <span class="kn">import</span> <span class="n">queryNextUtility</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">queryNextUtility</span><span class="p">(</span><span class="n">gutil</span><span class="p">,</span> <span class="n">IMyUtility</span><span class="p">,</span> <span class="s">&#39;myutil&#39;</span><span class="p">,</span> <span class="s">&#39;default&#39;</span><span class="p">)</span>
<span class="go">&#39;default&#39;</span>
</pre></div>
</div>
<p>Let&#8217;s now ensure that the function also works with multiple registries. First
we create another base registry:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">&gt;&gt;&gt; </span><span class="n">myregistry</span> <span class="o">=</span> <span class="n">Components</span><span class="p">()</span>
</pre></div>
</div>
<p>We now set up another utility into that registry:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">&gt;&gt;&gt; </span><span class="n">custom_util</span> <span class="o">=</span> <span class="n">MyUtility</span><span class="p">(</span><span class="s">&#39;my_custom_util&#39;</span><span class="p">,</span> <span class="n">myregistry</span><span class="p">)</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">myregistry</span><span class="o">.</span><span class="n">registerUtility</span><span class="p">(</span><span class="n">custom_util</span><span class="p">,</span> <span class="n">IMyUtility</span><span class="p">,</span> <span class="s">&#39;my_custom_util&#39;</span><span class="p">)</span>
</pre></div>
</div>
<p>We add it as a base to the local site manager:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">&gt;&gt;&gt; </span><span class="n">sm1</span><span class="o">.</span><span class="n">__bases__</span> <span class="o">=</span> <span class="p">(</span><span class="n">myregistry</span><span class="p">,)</span> <span class="o">+</span> <span class="n">sm1</span><span class="o">.</span><span class="n">__bases__</span>
</pre></div>
</div>
<p>Both the <tt class="docutils literal"><span class="pre">myregistry</span></tt> and global utilities should be available:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">&gt;&gt;&gt; </span><span class="n">queryNextUtility</span><span class="p">(</span><span class="n">sm1</span><span class="p">,</span> <span class="n">IMyUtility</span><span class="p">,</span> <span class="s">&#39;my_custom_util&#39;</span><span class="p">)</span>
<span class="go">MyUtility(&#39;my_custom_util&#39;)</span>
<span class="gp">&gt;&gt;&gt; </span><span class="n">queryNextUtility</span><span class="p">(</span><span class="n">sm1</span><span class="p">,</span> <span class="n">IMyUtility</span><span class="p">,</span> <span class="s">&#39;myutil&#39;</span><span class="p">)</span>
<span class="go">MyUtility(&#39;global&#39;)</span>
</pre></div>
</div>
<p>Note, if the context cannot be converted to a site manager, the default is
retruned:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">&gt;&gt;&gt; </span><span class="n">queryNextUtility</span><span class="p">(</span><span class="nb">object</span><span class="p">(),</span> <span class="n">IMyUtility</span><span class="p">,</span> <span class="s">&#39;myutil&#39;</span><span class="p">,</span> <span class="s">&#39;default&#39;</span><span class="p">)</span>
<span class="go">&#39;default&#39;</span>
</pre></div>
</div>
</div>
</div>


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