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<title>Module: Publisher</title>
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<td><strong>Module</strong></td>
<td class="class-name-in-header">Publisher</td>
</tr>
<tr class="top-aligned-row">
<td><strong>In:</strong></td>
<td>
<a href="../files/lib/utility/publisher_rb.html">
lib/utility/publisher.rb
</a>
<br />
</td>
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<area shape="rect" coords="16,16,109,65" href="Publisher.html" alt="Publisher
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<div id="description">
<p>
<a href="Publisher.html">Publisher</a> is a variation on Ruby‘s
Observable. We do not keep track of any changed state; instead we assume
that by virtue of calling <a href="Publisher.html#M000399">publish</a> we
have changed state. We do not allow serialization of subscribers. We allow
a <a href="Publisher.html">Publisher</a> to have multiple publications and
maintain separate lists of subscribers for each one.
</p>
</div>
</div>
<div id="method-list">
<h3 class="section-bar">Methods</h3>
<div class="name-list">
<a href="#M000399">publish</a>
<a href="#M000395">subscribe</a>
<a href="#M000398">subscriber_count</a>
<a href="#M000396">unsubscribe</a>
<a href="#M000397">unsubscribe_all</a>
</div>
</div>
</div>
<!-- if includes -->
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<!-- if method_list -->
<div id="methods">
<h3 class="section-bar">Public Instance methods</h3>
<div id="method-M000399" class="method-detail">
<a name="M000399"></a>
<div class="method-heading">
<a href="#M000399" class="method-signature">
<span class="method-name">publish</span><span class="method-args">(*arg)</span>
</a>
</div>
<div class="method-description">
<p>
If this object‘s changed state is <tt>true</tt>, invoke the update
method in each currently associated subscriber in turn, passing it the
given arguments. The changed state is then set to <tt>false</tt>.
</p>
<p><a class="source-toggle" href="#"
onclick="toggleCode('M000399-source');return false;">[Source]</a></p>
<div class="method-source-code" id="M000399-source">
<pre>
<span class="ruby-comment cmt"># File lib/utility/publisher.rb, line 65</span>
<span class="ruby-keyword kw">def</span> <span class="ruby-identifier">publish</span>(<span class="ruby-operator">*</span><span class="ruby-identifier">arg</span>)
<span class="ruby-keyword kw">if</span> <span class="ruby-keyword kw">defined?</span> <span class="ruby-ivar">@subscribers</span>
<span class="ruby-ivar">@subscribers</span>.<span class="ruby-identifier">dup</span>.<span class="ruby-identifier">each</span> <span class="ruby-keyword kw">do</span> <span class="ruby-operator">|</span><span class="ruby-identifier">s</span><span class="ruby-operator">|</span>
<span class="ruby-keyword kw">if</span> <span class="ruby-identifier">s</span>.<span class="ruby-identifier">respond_to?</span>(<span class="ruby-identifier">:to_int</span>)
<span class="ruby-constant">Engine</span>.<span class="ruby-identifier">instance</span>.<span class="ruby-identifier">db</span>.<span class="ruby-identifier">get</span>(<span class="ruby-identifier">s</span>).<span class="ruby-identifier">update</span>(<span class="ruby-operator">*</span><span class="ruby-identifier">arg</span>)
<span class="ruby-keyword kw">else</span>
<span class="ruby-identifier">s</span>.<span class="ruby-identifier">update</span>(<span class="ruby-operator">*</span><span class="ruby-identifier">arg</span>)
<span class="ruby-keyword kw">end</span>
<span class="ruby-keyword kw">end</span>
<span class="ruby-keyword kw">end</span>
<span class="ruby-keyword kw">end</span>
</pre>
</div>
</div>
</div>
<div id="method-M000395" class="method-detail">
<a name="M000395"></a>
<div class="method-heading">
<a href="#M000395" class="method-signature">
<span class="method-name">subscribe</span><span class="method-args">(subscriber)</span>
</a>
</div>
<div class="method-description">
<p>
Add <tt>subscriber</tt> as an subscriber on this object.
<tt>subscriber</tt> will now receive notifications.
</p>
<p><a class="source-toggle" href="#"
onclick="toggleCode('M000395-source');return false;">[Source]</a></p>
<div class="method-source-code" id="M000395-source">
<pre>
<span class="ruby-comment cmt"># File lib/utility/publisher.rb, line 30</span>
<span class="ruby-keyword kw">def</span> <span class="ruby-identifier">subscribe</span>(<span class="ruby-identifier">subscriber</span>)
<span class="ruby-ivar">@subscribers</span> <span class="ruby-operator">||=</span> []
<span class="ruby-keyword kw">if</span> <span class="ruby-operator">!</span><span class="ruby-identifier">subscriber</span>.<span class="ruby-identifier">respond_to?</span>(<span class="ruby-identifier">:to_int</span>) <span class="ruby-operator">&&</span> <span class="ruby-operator">!</span><span class="ruby-identifier">subscriber</span>.<span class="ruby-identifier">respond_to?</span>(<span class="ruby-identifier">:update</span>)
<span class="ruby-identifier">raise</span> <span class="ruby-constant">NoMethodError</span>, <span class="ruby-value str">"subscriber needs to respond to 'update'"</span>
<span class="ruby-keyword kw">end</span>
<span class="ruby-ivar">@subscribers</span>.<span class="ruby-identifier">push</span> <span class="ruby-identifier">subscriber</span>
<span class="ruby-keyword kw">end</span>
</pre>
</div>
</div>
</div>
<div id="method-M000398" class="method-detail">
<a name="M000398"></a>
<div class="method-heading">
<a href="#M000398" class="method-signature">
<span class="method-name">subscriber_count</span><span class="method-args">()</span>
</a>
</div>
<div class="method-description">
<p>
Count of subscribers to this object.
</p>
<p><a class="source-toggle" href="#"
onclick="toggleCode('M000398-source');return false;">[Source]</a></p>
<div class="method-source-code" id="M000398-source">
<pre>
<span class="ruby-comment cmt"># File lib/utility/publisher.rb, line 56</span>
<span class="ruby-keyword kw">def</span> <span class="ruby-identifier">subscriber_count</span>
<span class="ruby-ivar">@subscribers</span> <span class="ruby-operator">?</span> <span class="ruby-ivar">@subscribers</span>.<span class="ruby-identifier">size</span> <span class="ruby-operator">:</span> <span class="ruby-value">0</span>
<span class="ruby-keyword kw">end</span>
</pre>
</div>
</div>
</div>
<div id="method-M000396" class="method-detail">
<a name="M000396"></a>
<div class="method-heading">
<a href="#M000396" class="method-signature">
<span class="method-name">unsubscribe</span><span class="method-args">(subscriber)</span>
</a>
</div>
<div class="method-description">
<p>
Delete <tt>subscriber</tt> as a subscriber on this object. It will no
longer receive notifications.
</p>
<p><a class="source-toggle" href="#"
onclick="toggleCode('M000396-source');return false;">[Source]</a></p>
<div class="method-source-code" id="M000396-source">
<pre>
<span class="ruby-comment cmt"># File lib/utility/publisher.rb, line 42</span>
<span class="ruby-keyword kw">def</span> <span class="ruby-identifier">unsubscribe</span>(<span class="ruby-identifier">subscriber</span>)
<span class="ruby-ivar">@subscribers</span>.<span class="ruby-identifier">delete</span> <span class="ruby-identifier">subscriber</span> <span class="ruby-keyword kw">if</span> <span class="ruby-keyword kw">defined?</span> <span class="ruby-ivar">@subscribers</span>
<span class="ruby-keyword kw">end</span>
</pre>
</div>
</div>
</div>
<div id="method-M000397" class="method-detail">
<a name="M000397"></a>
<div class="method-heading">
<a href="#M000397" class="method-signature">
<span class="method-name">unsubscribe_all</span><span class="method-args">()</span>
</a>
</div>
<div class="method-description">
<p>
Delete all subscribers associated with this object.
</p>
<p><a class="source-toggle" href="#"
onclick="toggleCode('M000397-source');return false;">[Source]</a></p>
<div class="method-source-code" id="M000397-source">
<pre>
<span class="ruby-comment cmt"># File lib/utility/publisher.rb, line 49</span>
<span class="ruby-keyword kw">def</span> <span class="ruby-identifier">unsubscribe_all</span>
<span class="ruby-ivar">@subscribers</span>.<span class="ruby-identifier">clear</span> <span class="ruby-keyword kw">if</span> <span class="ruby-keyword kw">defined?</span> <span class="ruby-ivar">@subscribers</span>
<span class="ruby-keyword kw">end</span>
</pre>
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