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EnumeratedString.html
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EnumeratedString.html
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<section id="enumeratedstring">
<span id="id1"></span><h1>EnumeratedString<a class="headerlink" href="#enumeratedstring" title="Link to this heading">¶</a></h1>
<nav class="contents local" id="contents">
<ul class="simple">
<li><p><a class="reference internal" href="#why-enumeratedstring" id="id2">Why EnumeratedString?</a></p></li>
<li><p><a class="reference internal" href="#how-to-use-the-enumeratedstring" id="id3">How to use the EnumeratedString</a></p></li>
<li><p><a class="reference internal" href="#example-use-of-enumeratedstring" id="id4">Example Use of EnumeratedString</a></p></li>
</ul>
</nav>
<section id="why-enumeratedstring">
<h2><a class="toc-backref" href="#id2" role="doc-backlink">Why EnumeratedString?</a><a class="headerlink" href="#why-enumeratedstring" title="Link to this heading">¶</a></h2>
<p>It is common for a property to be a string, the value of which must be one of several enumerated values. Programmatically,
this is representing an <code class="docutils literal notranslate"><span class="pre">enum</span></code> object in C++, but based on a set of strings instead of integer-types. What would be ideal
would be something like the following:</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="k">enum</span><span class="w"> </span><span class="k">class</span><span class="w"> </span><span class="nc">StringPropertyOptions</span><span class="o">:</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="w"> </span><span class="p">{</span><span class="n">option1</span><span class="o">=</span><span class="s">"OptionOne"</span><span class="p">,</span><span class="w"> </span><span class="p">...</span><span class="w"> </span><span class="p">};</span>
</pre></div>
</div>
<p>However, this is not allowed under C++.</p>
<p>The <code class="docutils literal notranslate"><span class="pre">EnumeratedString</span></code> objects allow for binding an <code class="docutils literal notranslate"><span class="pre">enum</span></code> or <code class="docutils literal notranslate"><span class="pre">enum</span> <span class="pre">class</span></code> to a vector of strings, allowing for much
of the same behavior. This allows for easy-to-read <code class="docutils literal notranslate"><span class="pre">if</span></code> and <code class="docutils literal notranslate"><span class="pre">switch</span></code> statements, as well as easy conversions and assignments
with strings from the allowed set. This further adds an additional layer of validation for string properties, in additon to the
<code class="docutils literal notranslate"><span class="pre">StringListValidator</span></code> used in the property declaration.</p>
</section>
<section id="how-to-use-the-enumeratedstring">
<h2><a class="toc-backref" href="#id3" role="doc-backlink">How to use the EnumeratedString</a><a class="headerlink" href="#how-to-use-the-enumeratedstring" title="Link to this heading">¶</a></h2>
<p>First include the <code class="docutils literal notranslate"><span class="pre">EnumeratedString.h</span></code> header file.</p>
<p>This is a template class, and its three template parameters are the name of an <code class="docutils literal notranslate"><span class="pre">enum</span></code> type, a <em>pointer</em> to static vector of
<code class="docutils literal notranslate"><span class="pre">std::string</span></code> objects, and an optional <em>pointer</em> to a statically defined <code class="docutils literal notranslate"><span class="pre">std::function</span></code> for comparing <code class="docutils literal notranslate"><span class="pre">std::string</span></code> objects. The last
template parameter is defaulted to <code class="docutils literal notranslate"><span class="pre">compareStrings</span></code> which implements a case-sensitive string comparison. A predefined function for case-insensitive
string comparison, <code class="docutils literal notranslate"><span class="pre">compareStringsCaseInsensitive</span></code>, is also provided as an option.</p>
<p>Below is an example. Consider the mantid algorithm <code class="code docutils literal notranslate"><span class="pre">BakeCake</span></code>, which has a string property,
<code class="docutils literal notranslate"><span class="pre">CakeType</span></code>. This algorithm only knows how to bake a few types of cakes. The allowed types of cake the user can set for
this property are limited to “Lemon”, “Bundt”, and “Pound”.</p>
<p>The <code class="docutils literal notranslate"><span class="pre">EnumeratedString</span></code> should be setup as follows:</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="cp">#include</span><span class="w"> </span><span class="cpf">"MantidKernel/EnumeratedString.h"</span>
<span class="k">namespace</span><span class="w"> </span><span class="nn">Mantid</span><span class="w"> </span><span class="p">{</span>
<span class="k">namespace</span><span class="w"> </span><span class="p">{</span>
<span class="k">enum</span><span class="w"> </span><span class="k">class</span><span class="w"> </span><span class="nc">CakeTypeEnum</span><span class="w"> </span><span class="p">{</span><span class="n">LEMON</span><span class="p">,</span><span class="w"> </span><span class="n">BUNDT</span><span class="p">,</span><span class="w"> </span><span class="n">POUND</span><span class="p">,</span><span class="w"> </span><span class="n">enum_count</span><span class="p">};</span>
<span class="k">const</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o"><</span><span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="o">></span><span class="w"> </span><span class="n">cakeTypeNames</span><span class="w"> </span><span class="p">{</span><span class="s">"Lemon"</span><span class="p">,</span><span class="w"> </span><span class="s">"Bundt"</span><span class="p">,</span><span class="w"> </span><span class="s">"Pound"</span><span class="p">};</span>
<span class="c1">// optional typedef</span>
<span class="k">typedef</span><span class="w"> </span><span class="n">EnumeratedString</span><span class="o"><</span><span class="n">CakeEnumType</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">cakeTypeNames</span><span class="o">></span><span class="w"> </span><span class="n">CAKETYPE</span><span class="p">;</span>
<span class="p">}</span><span class="w"> </span><span class="c1">// namespace</span>
<span class="c1">// ...</span>
<span class="c1">// initialize an object</span>
<span class="n">EnumeratedString</span><span class="o"><</span><span class="n">CakeTypeEnum</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">cakeTypeNames</span><span class="o">></span><span class="w"> </span><span class="n">cake1</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">CakeTypeEnum</span><span class="o">::</span><span class="n">LEMON</span><span class="p">;</span>
<span class="n">EnumeratedString</span><span class="o"><</span><span class="n">CakeTypeEnum</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">cakeTypeNames</span><span class="o">></span><span class="w"> </span><span class="n">cake2</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">"Lemon"</span><span class="p">;</span>
<span class="c1">//init from the typedef</span>
<span class="n">CAKETYPE</span><span class="w"> </span><span class="n">cake3</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="s">"Pound"</span><span class="p">;</span>
<span class="kt">bool</span><span class="w"> </span><span class="n">sameCake</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">(</span><span class="n">cake1</span><span class="o">==</span><span class="n">cake2</span><span class="p">);</span><span class="w"> </span><span class="c1">//sameCake = true, a Lemon cake is a Lemon cake</span>
<span class="kt">bool</span><span class="w"> </span><span class="n">notSameCake</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="p">(</span><span class="n">cake1</span><span class="o">!=</span><span class="n">cake3</span><span class="p">);</span><span class="w"> </span><span class="c1">//notSameCake = true, a Lemon cake is not a Pound cake</span>
</pre></div>
</div>
<p>Notice that the final element of the <code class="docutils literal notranslate"><span class="pre">enum</span></code> is called <code class="code docutils literal notranslate"><span class="pre">enum_count</span></code>. This is mandatory. This element indicates the
number of elements inside the <code class="docutils literal notranslate"><span class="pre">enum</span></code>, and used for verifying compatibility with the vector of strings. A compiler error
will be triggered if this is not included.</p>
<p>Further, the <code class="docutils literal notranslate"><span class="pre">enum</span></code> <em>must</em> have elements in order from 0 to <code class="code docutils literal notranslate"><span class="pre">enum_count</span></code>. That is, you <em>CANNOT</em> set them like so:</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="k">enum</span><span class="w"> </span><span class="k">class</span><span class="w"> </span><span class="nc">CakeTypeEnum</span><span class="w"> </span><span class="o">:</span><span class="w"> </span><span class="kt">char</span><span class="w"> </span><span class="p">{</span><span class="n">LEMON</span><span class="o">=</span><span class="sc">'l'</span><span class="p">,</span><span class="w"> </span><span class="n">BUNDT</span><span class="o">=</span><span class="sc">'b'</span><span class="p">,</span><span class="w"> </span><span class="n">POUND</span><span class="o">=</span><span class="sc">'p'</span><span class="p">,</span><span class="w"> </span><span class="n">enum_count</span><span class="o">=</span><span class="mi">3</span><span class="p">};</span><span class="w"> </span><span class="c1">// NOT ALLOWED</span>
</pre></div>
</div>
<p>as this will break validation features inside the class.</p>
<p>Notice the use of the reference operator, <code class="code docutils literal notranslate"><span class="pre">&cakeTypeNames</span></code>, and <em>not</em> <code class="code docutils literal notranslate"><span class="pre">cakeTypeNames</span></code>.</p>
<p>In the above code, a <code class="code docutils literal notranslate"><span class="pre">CAKETYPE</span></code> object can be created either from a <code class="code docutils literal notranslate"><span class="pre">CakeTypeEnum</span></code>, or from one of the strings
in the <code class="code docutils literal notranslate"><span class="pre">cakeTypeNames</span></code> array (either by the literal, or by accessig it in the array), or from another <code class="code docutils literal notranslate"><span class="pre">CAKETYPE</span></code>
object. The only assignment/comparison not directly possible is from <code class="code docutils literal notranslate"><span class="pre">CakeTypeEnum</span></code> to one of the strings. Otherwise
free conversion and comparison from <code class="code docutils literal notranslate"><span class="pre">CAKETYPE</span></code>, <code class="code docutils literal notranslate"><span class="pre">CakeTypeEnum</span></code>, and strings from <code class="code docutils literal notranslate"><span class="pre">cakeTypeNames</span></code> is possible.</p>
</section>
<section id="example-use-of-enumeratedstring">
<h2><a class="toc-backref" href="#id4" role="doc-backlink">Example Use of EnumeratedString</a><a class="headerlink" href="#example-use-of-enumeratedstring" title="Link to this heading">¶</a></h2>
<p>An example of where this might be used inside an algorithm is shown below:</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="cp">#include</span><span class="w"> </span><span class="cpf">"MantidAlgorithms/BakeCake.h"</span>
<span class="cp">#include</span><span class="w"> </span><span class="cpf">"MantidKernel/EnumeratedString.h"</span>
<span class="k">namespace</span><span class="w"> </span><span class="nn">Mantid</span><span class="w"> </span><span class="p">{</span>
<span class="k">namespace</span><span class="w"> </span><span class="p">{</span>
<span class="k">enum</span><span class="w"> </span><span class="k">class</span><span class="w"> </span><span class="nc">CakeTypeEnum</span><span class="w"> </span><span class="p">{</span><span class="n">LEMON</span><span class="p">,</span><span class="w"> </span><span class="n">BUNDT</span><span class="p">,</span><span class="w"> </span><span class="n">POUND</span><span class="p">,</span><span class="w"> </span><span class="n">enum_count</span><span class="p">};</span>
<span class="k">const</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o"><</span><span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="o">></span><span class="w"> </span><span class="n">cakeTypeNames</span><span class="w"> </span><span class="p">{</span><span class="s">"Lemon"</span><span class="p">,</span><span class="w"> </span><span class="s">"Bundt"</span><span class="p">,</span><span class="w"> </span><span class="s">"Pound"</span><span class="p">};</span>
<span class="k">typedef</span><span class="w"> </span><span class="n">EnumeratedString</span><span class="o"><</span><span class="n">CakeEnumType</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">cakeTypeNames</span><span class="o">></span><span class="w"> </span><span class="n">CAKETYPE</span><span class="p">;</span>
<span class="p">}</span><span class="w"> </span><span class="c1">// namespace</span>
<span class="k">namespace</span><span class="w"> </span><span class="nn">Algorithms</span><span class="w"> </span><span class="p">{</span>
<span class="kt">void</span><span class="w"> </span><span class="nf">BakeCake::init</span><span class="p">()</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="c1">// the StringListValidator is optional, but fails faster; the CAKETYPE cannot be set with string not in list</span>
<span class="w"> </span><span class="n">declareProperty</span><span class="p">(</span><span class="s">"CakeType"</span><span class="p">,</span><span class="w"> </span><span class="s">"Bundt"</span><span class="p">,</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">make_shared</span><span class="o"><</span><span class="n">Mantid</span><span class="o">::</span><span class="n">Kernel</span><span class="o">::</span><span class="n">StringListValidator</span><span class="o">></span><span class="p">(</span><span class="n">cakeTypeNames</span><span class="p">),</span>
<span class="w"> </span><span class="s">"Mandatory. The kind of cake for algorithm to bake."</span><span class="p">);</span>
<span class="p">}</span>
<span class="kt">void</span><span class="w"> </span><span class="nf">BakeCake::exec</span><span class="p">()</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="c1">// this will assign cakeType from the string property</span>
<span class="w"> </span><span class="n">CAKETYPE</span><span class="w"> </span><span class="n">cakeType</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">getPropertyValue</span><span class="p">(</span><span class="s">"CakeType"</span><span class="p">);</span>
<span class="w"> </span><span class="c1">// logic can branch on cakeType comparing to the enum</span>
<span class="w"> </span><span class="k">switch</span><span class="p">(</span><span class="n">cakeType</span><span class="p">){</span>
<span class="w"> </span><span class="k">case</span><span class="w"> </span><span class="no">CakeTypeEnum</span><span class="o">::</span><span class="no">LEMON</span><span class="p">:</span>
<span class="w"> </span><span class="n">bakeLemonCake</span><span class="p">();</span>
<span class="w"> </span><span class="k">break</span><span class="p">;</span>
<span class="w"> </span><span class="k">case</span><span class="w"> </span><span class="no">CakeTypeEnum</span><span class="o">::</span><span class="no">BUNDT</span><span class="p">:</span>
<span class="w"> </span><span class="n">bakeBundtCake</span><span class="p">();</span>
<span class="w"> </span><span class="k">break</span><span class="p">;</span>
<span class="w"> </span><span class="k">case</span><span class="w"> </span><span class="no">CakeTypeEnum</span><span class="o">::</span><span class="no">POUND</span><span class="p">:</span>
<span class="w"> </span><span class="n">bakePoundCake</span><span class="p">();</span>
<span class="w"> </span><span class="k">break</span><span class="p">;</span>
<span class="w"> </span><span class="p">}</span>
<span class="w"> </span><span class="n">getLemonsForCake</span><span class="p">(</span><span class="s">"Bundt"</span><span class="p">);</span>
<span class="w"> </span><span class="n">getIngredientsForCake</span><span class="p">(</span><span class="n">cakeType</span><span class="p">);</span>
<span class="w"> </span><span class="c1">// other ways to compare</span>
<span class="w"> </span><span class="k">if</span><span class="p">(</span><span class="n">cakeType</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="s">"Lemon"</span><span class="p">){</span>
<span class="w"> </span><span class="n">g_log</span><span class="p">.</span><span class="n">information</span><span class="p">()</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="s">"Baking a lemon cake</span><span class="se">\n</span><span class="s">"</span><span class="p">;</span>
<span class="w"> </span><span class="p">}</span>
<span class="w"> </span><span class="k">if</span><span class="p">(</span><span class="n">cakeType</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">CakeTypeEnum</span><span class="o">::</span><span class="n">BUNDT</span><span class="p">){</span>
<span class="w"> </span><span class="n">g_log</span><span class="p">.</span><span class="n">information</span><span class="p">()</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="s">"Baking a bundt cake</span><span class="se">\n</span><span class="s">"</span><span class="p">;</span>
<span class="w"> </span><span class="p">}</span>
<span class="w"> </span><span class="n">CAKETYPE</span><span class="w"> </span><span class="n">poundCake</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">CakeTypeEnum</span><span class="o">::</span><span class="n">POUND</span><span class="p">;</span>
<span class="w"> </span><span class="k">if</span><span class="p">(</span><span class="n">cakeType</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">poundCake</span><span class="p">){</span>
<span class="w"> </span><span class="n">g_log</span><span class="p">.</span><span class="n">information</span><span class="p">()</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="s">"Baking a pound cake</span><span class="se">\n</span><span class="s">"</span><span class="p">;</span>
<span class="w"> </span><span class="p">}</span>
<span class="p">}</span>
<span class="kt">void</span><span class="w"> </span><span class="nf">BakeCake::getLemonsForCake</span><span class="p">(</span><span class="n">CAKETYPE</span><span class="w"> </span><span class="n">cakeType</span><span class="p">){</span>
<span class="w"> </span><span class="k">if</span><span class="p">(</span><span class="n">cakeType</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">CakeTypeEnum</span><span class="o">::</span><span class="n">LEMON</span><span class="p">){</span>
<span class="w"> </span><span class="n">g_log</span><span class="p">.</span><span class="n">information</span><span class="p">()</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="s">"Getting some lemons!</span><span class="se">\n</span><span class="s">"</span><span class="p">;</span>
<span class="w"> </span><span class="p">}</span><span class="w"> </span><span class="k">else</span><span class="w"> </span><span class="p">{</span>
<span class="w"> </span><span class="n">g_log</span><span class="p">.</span><span class="n">information</span><span class="p">()</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="s">"I have no need for lemons.</span><span class="se">\n</span><span class="s">"</span><span class="p">;</span>
<span class="w"> </span><span class="p">}</span>
<span class="p">}</span>
<span class="kt">void</span><span class="w"> </span><span class="nf">BakeCake::getIngredientsForCake</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="w"> </span><span class="n">cakeType</span><span class="p">){</span>
<span class="w"> </span><span class="n">g_log</span><span class="p">.</span><span class="n">information</span><span class="p">()</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="s">"Retrieving ingredients for a "</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="n">cakeType</span><span class="w"> </span><span class="o"><<</span><span class="w"> </span><span class="s">" cake!</span><span class="se">\n</span><span class="s">"</span><span class="p">;</span>
<span class="p">}</span>
<span class="p">}</span><span class="c1">// namespace Algorithms</span>
<span class="p">}</span><span class="c1">// namespace Mantid</span>
</pre></div>
</div>
<p>This will easily handle branching logic on the basis of a set number of possible string values, using an <code class="docutils literal notranslate"><span class="pre">enum</span></code> to base the set of strings.</p>
<p>In the code examples above, if you don’t want to distinguish between names like “Lemon” and “LEMON”, you can define your <code class="docutils literal notranslate"><span class="pre">CAKETYPE</span></code> as case-insensitive:</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="cp">#include</span><span class="w"> </span><span class="cpf">"MantidKernel/EnumeratedString.h"</span>
<span class="k">namespace</span><span class="w"> </span><span class="nn">Mantid</span><span class="w"> </span><span class="p">{</span>
<span class="k">namespace</span><span class="w"> </span><span class="p">{</span>
<span class="k">enum</span><span class="w"> </span><span class="k">class</span><span class="w"> </span><span class="nc">CakeTypeEnum</span><span class="w"> </span><span class="p">{</span><span class="n">LEMON</span><span class="p">,</span><span class="w"> </span><span class="n">BUNDT</span><span class="p">,</span><span class="w"> </span><span class="n">POUND</span><span class="p">,</span><span class="w"> </span><span class="n">enum_count</span><span class="p">};</span>
<span class="k">const</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o"><</span><span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="o">></span><span class="w"> </span><span class="n">cakeTypeNames</span><span class="w"> </span><span class="p">{</span><span class="s">"Lemon"</span><span class="p">,</span><span class="w"> </span><span class="s">"Bundt"</span><span class="p">,</span><span class="w"> </span><span class="s">"Pound"</span><span class="p">};</span>
<span class="c1">// optional typedef</span>
<span class="k">typedef</span><span class="w"> </span><span class="n">EnumeratedString</span><span class="o"><</span><span class="n">CakeEnumType</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">cakeTypeNames</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">compareStringsCaseInsensitive</span><span class="o">></span><span class="w"> </span><span class="n">CAKETYPE</span><span class="p">;</span>
<span class="p">}</span><span class="w"> </span><span class="c1">// namespace</span>
</pre></div>
</div>
<p>You can also provide your own string comparator like <code class="docutils literal notranslate"><span class="pre">firstLetterComparator</span></code> shown below:</p>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="cp">#include</span><span class="w"> </span><span class="cpf">"MantidKernel/EnumeratedString.h"</span>
<span class="k">namespace</span><span class="w"> </span><span class="nn">Mantid</span><span class="w"> </span><span class="p">{</span>
<span class="k">namespace</span><span class="w"> </span><span class="p">{</span>
<span class="n">std</span><span class="o">::</span><span class="n">function</span><span class="o"><</span><span class="kt">bool</span><span class="p">(</span><span class="k">const</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="w"> </span><span class="o">&</span><span class="p">,</span><span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="w"> </span><span class="o">&</span><span class="p">)</span><span class="o">></span><span class="w"> </span><span class="n">firstLetterComparator</span><span class="w"> </span><span class="o">=</span>
<span class="w"> </span><span class="p">[](</span><span class="k">const</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="w"> </span><span class="o">&</span><span class="n">x</span><span class="p">,</span><span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="w"> </span><span class="o">&</span><span class="n">y</span><span class="p">)</span><span class="w"> </span><span class="p">{</span><span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="n">x</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">y</span><span class="p">[</span><span class="mi">0</span><span class="p">];</span><span class="w"> </span><span class="p">};</span>
<span class="k">enum</span><span class="w"> </span><span class="k">class</span><span class="w"> </span><span class="nc">CakeTypeEnum</span><span class="w"> </span><span class="p">{</span><span class="n">L</span><span class="p">,</span><span class="w"> </span><span class="n">B</span><span class="p">,</span><span class="w"> </span><span class="n">P</span><span class="p">,</span><span class="w"> </span><span class="n">enum_count</span><span class="p">};</span>
<span class="k">const</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">vector</span><span class="o"><</span><span class="n">std</span><span class="o">::</span><span class="n">string</span><span class="o">></span><span class="w"> </span><span class="n">cakeTypeFirstLetters</span><span class="w"> </span><span class="p">{</span><span class="s">"L"</span><span class="p">,</span><span class="w"> </span><span class="s">"B"</span><span class="p">,</span><span class="w"> </span><span class="s">"P"</span><span class="p">};</span>
<span class="c1">// optional typedef</span>
<span class="k">typedef</span><span class="w"> </span><span class="n">EnumeratedString</span><span class="o"><</span><span class="n">CakeEnumType</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">cakeTypeFirstLetters</span><span class="p">,</span><span class="w"> </span><span class="o">&</span><span class="n">firstLetterComparator</span><span class="o">></span><span class="w"> </span><span class="n">CAKETYPE</span><span class="p">;</span>
<span class="p">}</span><span class="w"> </span><span class="c1">// namespace</span>
</pre></div>
</div>
<p>in which case a “Lemon” cake will get the same <code class="docutils literal notranslate"><span class="pre">enum</span></code> value as a “Lime” cake.</p>
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