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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<title>Valued Properties</title>
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<ul class="crumbs"><li><a href="../index.html">Home</a></li><li><a href="../inform7n.html">Inform7</a></li><li><a href="index.html">knowledge</a></li><li><a href="index.html#3">Chapter 3: Properties</a></li><li><b>Valued Properties</b></li></ul></div>
<p class="purpose">Properties which attach values to subjects, with such values always having a given kind.</p>
<ul class="toc"><li><a href="3-vp.html#SP1">&#167;1. Initialising details</a></li><li><a href="3-vp.html#SP2">&#167;2. Requesting new named properties</a></li><li><a href="3-vp.html#SP4">&#167;4. Requesting new nameless properties</a></li><li><a href="3-vp.html#SP5">&#167;5. The setting relation</a></li><li><a href="3-vp.html#SP6">&#167;6. Details</a></li><li><a href="3-vp.html#SP7">&#167;7. Coincidence</a></li><li><a href="3-vp.html#SP8">&#167;8. Storing relations</a></li><li><a href="3-vp.html#SP9">&#167;9. Assertion</a></li></ul><hr class="tocbar">
<p class="commentary firstcommentary"><a id="SP1" class="paragraph-anchor"></a><b>&#167;1. Initialising details. </b>Each valued property has the following small block of data attached:
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">typedef</span><span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="reserved-syntax">value_property_data</span><span class="plain-syntax"> {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="identifier-syntax">kind</span><span class="plain-syntax"> *</span><span class="identifier-syntax">property_value_kind</span><span class="plain-syntax">; </span><span class="comment-syntax"> if not either/or, what kind of value does it hold?</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="identifier-syntax">binary_predicate</span><span class="plain-syntax"> *</span><span class="identifier-syntax">setting_bp</span><span class="plain-syntax">; </span><span class="comment-syntax"> and which relation sets it?</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="identifier-syntax">binary_predicate</span><span class="plain-syntax"> *</span><span class="identifier-syntax">relation_whose_state_this_stores</span><span class="plain-syntax">; </span><span class="comment-syntax"> or </span><span class="extract"><span class="extract-syntax">NULL</span></span><span class="comment-syntax"> if it doesn't</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">struct</span><span class="plain-syntax"> </span><span class="reserved-syntax">condition_of_subject</span><span class="plain-syntax"> *</span><span class="identifier-syntax">as_condition_of_subject</span><span class="plain-syntax">; </span><span class="comment-syntax"> or </span><span class="extract"><span class="extract-syntax">NULL</span></span><span class="comment-syntax"> if it isn't one</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">name_coincides_with_kind</span><span class="plain-syntax">; </span><span class="comment-syntax"> and is its name the same as that of a kind?</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">CLASS_DEFINITION</span>
<span class="plain-syntax">} </span><span class="reserved-syntax">value_property_data</span><span class="plain-syntax">;</span>
<span class="reserved-syntax">value_property_data</span><span class="plain-syntax"> *</span><span class="function-syntax">ValueProperties::new_value_data</span><button class="popup" onclick="togglePopup('usagePopup1')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup1">Usage of <span class="code-font"><span class="function-syntax">ValueProperties::new_value_data</span></span>:<br/>Properties - <a href="3-prp.html#SP3_3">&#167;3.3</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">property</span><span class="plain-syntax"> *</span><span class="identifier-syntax">prn</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">value_property_data</span><span class="plain-syntax"> *</span><span class="identifier-syntax">vod</span><span class="plain-syntax"> = </span><span class="identifier-syntax">CREATE</span><span class="plain-syntax">(</span><span class="reserved-syntax">value_property_data</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">vod</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">property_value_kind</span><span class="plain-syntax"> = </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">vod</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">setting_bp</span><span class="plain-syntax"> = </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">vod</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">name_coincides_with_kind</span><span class="plain-syntax"> = </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">vod</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">as_condition_of_subject</span><span class="plain-syntax"> = </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">vod</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">relation_whose_state_this_stores</span><span class="plain-syntax"> = </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">vod</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
</pre>
<ul class="endnotetexts"><li>The structure value_property_data is accessed in 3/prp, 4/cos and here.</li></ul>
<p class="commentary firstcommentary"><a id="SP2" class="paragraph-anchor"></a><b>&#167;2. Requesting new named properties. </b>Recall that there is just one property with any given name. This returns it,
or creates it if it doesn't exist. (If it does exist but is either-or, then
<a href="3-prp.html#SP2" class="internal">Properties::obtain</a> will throw an internal error: so be careful.)
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">property</span><span class="plain-syntax"> *</span><span class="function-syntax">ValueProperties::obtain</span><button class="popup" onclick="togglePopup('usagePopup2')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup2">Usage of <span class="code-font"><span class="function-syntax">ValueProperties::obtain</span></span>:<br/>Conditions of Subjects - <a href="4-cos.html#SP3_4">&#167;3.4</a></span></button><span class="plain-syntax">(</span><span class="identifier-syntax">wording</span><span class="plain-syntax"> </span><span class="identifier-syntax">W</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><a href="3-prp.html#SP2" class="function-link"><span class="function-syntax">Properties::obtain</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">W</span><span class="plain-syntax">, </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">);</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP3" class="paragraph-anchor"></a><b>&#167;3. </b>Now the same: except that we require the property to have a given kind of
value, so that the process can go awry. (But we are allowed to avoid this
possibility by widening the kind, when this can be done.)
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">property</span><span class="plain-syntax"> *</span><span class="function-syntax">ValueProperties::obtain_within_kind</span><span class="plain-syntax">(</span><span class="identifier-syntax">wording</span><span class="plain-syntax"> </span><span class="identifier-syntax">W</span><span class="plain-syntax">, </span><span class="identifier-syntax">kind</span><span class="plain-syntax"> *</span><span class="identifier-syntax">K</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">property</span><span class="plain-syntax"> *</span><span class="identifier-syntax">prn</span><span class="plain-syntax"> = </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">K</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) </span><span class="identifier-syntax">K</span><span class="plain-syntax"> = </span><span class="identifier-syntax">K_object</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">K</span><span class="plain-syntax"> = </span><span class="identifier-syntax">Kinds::weaken</span><span class="plain-syntax">(</span><span class="identifier-syntax">K</span><span class="plain-syntax">, </span><span class="identifier-syntax">K_object</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="function-syntax">&lt;property-name&gt;</span><span class="plain-syntax">(</span><span class="identifier-syntax">W</span><span class="plain-syntax">)) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">prn</span><span class="plain-syntax"> = </span><span class="function-syntax">&lt;&lt;rp&gt;&gt;</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">prn</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">value_data</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) </span><span class="named-paragraph-container code-font"><a href="3-vp.html#SP3_1" class="named-paragraph-link"><span class="named-paragraph">Issue an incompatible property kind message</span><span class="named-paragraph-number">3.1</span></a></span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">kind</span><span class="plain-syntax"> *</span><span class="identifier-syntax">existing_kind</span><span class="plain-syntax"> = </span><span class="identifier-syntax">prn</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">value_data</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">property_value_kind</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">switch</span><span class="plain-syntax">(</span><span class="identifier-syntax">Kinds::compatible</span><span class="plain-syntax">(</span><span class="identifier-syntax">K</span><span class="plain-syntax">, </span><span class="identifier-syntax">existing_kind</span><span class="plain-syntax">)) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">case</span><span class="plain-syntax"> </span><span class="identifier-syntax">SOMETIMES_MATCH:</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">Kinds::compatible</span><span class="plain-syntax">(</span><span class="identifier-syntax">existing_kind</span><span class="plain-syntax">, </span><span class="identifier-syntax">K</span><span class="plain-syntax">) != </span><span class="identifier-syntax">ALWAYS_MATCH</span><span class="plain-syntax">)</span>
<span class="plain-syntax"> </span><span class="named-paragraph-container code-font"><a href="3-vp.html#SP3_1" class="named-paragraph-link"><span class="named-paragraph">Issue an incompatible property kind message</span><span class="named-paragraph-number">3.1</span></a></span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">prn</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">value_data</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">property_value_kind</span><span class="plain-syntax"> = </span><span class="identifier-syntax">K</span><span class="plain-syntax">; </span><span class="comment-syntax"> widen the kind</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">break</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">case</span><span class="plain-syntax"> </span><span class="identifier-syntax">NEVER_MATCH:</span>
<span class="plain-syntax"> </span><span class="named-paragraph-container code-font"><a href="3-vp.html#SP3_1" class="named-paragraph-link"><span class="named-paragraph">Issue an incompatible property kind message</span><span class="named-paragraph-number">3.1</span></a></span><span class="plain-syntax">;</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> } </span><span class="reserved-syntax">else</span><span class="plain-syntax"> {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">prn</span><span class="plain-syntax"> = </span><a href="3-prp.html#SP2" class="function-link"><span class="function-syntax">Properties::obtain</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">W</span><span class="plain-syntax">, </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">prn</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">value_data</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">property_value_kind</span><span class="plain-syntax"> = </span><span class="identifier-syntax">K</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">prn</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP3_1" class="paragraph-anchor"></a><b>&#167;3.1. </b><span class="named-paragraph-container code-font"><span class="named-paragraph-defn">Issue an incompatible property kind message</span><span class="named-paragraph-number">3.1</span></span><span class="comment-syntax"> =</span>
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax"> </span><span class="identifier-syntax">StandardProblems::sentence_problem</span><span class="plain-syntax">(</span><span class="identifier-syntax">Task::syntax_tree</span><span class="plain-syntax">(),</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">_p_</span><span class="plain-syntax">(</span><span class="identifier-syntax">PM_BadKOVForRelationProperty</span><span class="plain-syntax">),</span>
<span class="plain-syntax"> </span><span class="string-syntax">"that property already exists and contains a kind of value incompatible "</span>
<span class="plain-syntax"> </span><span class="string-syntax">"with what we need here"</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="string-syntax">"so you will need to give it a different name."</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">;</span>
</pre>
<ul class="endnotetexts"><li>This code is used in <a href="3-vp.html#SP3">&#167;3</a> (three times).</li></ul>
<p class="commentary firstcommentary"><a id="SP4" class="paragraph-anchor"></a><b>&#167;4. Requesting new nameless properties. </b>Sometimes we will want a property which exists at run-time but which
has no name or visible existence at the Inform source text level. For
instance, the run-time code needs a property called <span class="extract"><span class="extract-syntax">vector</span></span> in which to
store partial results when finding routes through maps, but <span class="extract"><span class="extract-syntax">vector</span></span> is
nameless in the source text, unrecorded in the Index, and generally invisible
to the end user.
</p>
<p class="commentary">Core Inform creates no such properties, but many of the features do.
</p>
<p class="commentary">The function comes in two forms: one where we already have an iname we want
the property to have, and one where we just have the text of such a name.
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">property</span><span class="plain-syntax"> *</span><span class="function-syntax">ValueProperties::new_nameless</span><button class="popup" onclick="togglePopup('usagePopup3')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup3">Usage of <span class="code-font"><span class="function-syntax">ValueProperties::new_nameless</span></span>:<br/>The Model World - <a href="5-tmw.html#SP3">&#167;3</a></span></button><span class="plain-syntax">(</span><span class="identifier-syntax">text_stream</span><span class="plain-syntax"> *</span><span class="identifier-syntax">Inter_identifier</span><span class="plain-syntax">, </span><span class="identifier-syntax">kind</span><span class="plain-syntax"> *</span><span class="identifier-syntax">K</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">K</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) </span><span class="identifier-syntax">internal_error</span><span class="plain-syntax">(</span><span class="string-syntax">"new nameless property without kind"</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">property</span><span class="plain-syntax"> *</span><span class="identifier-syntax">prn</span><span class="plain-syntax"> = </span><a href="3-prp.html#SP3" class="function-link"><span class="function-syntax">Properties::create</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">EMPTY_WORDING</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Hierarchy::completion_package</span><span class="plain-syntax">(</span><span class="identifier-syntax">PROPERTIES_HAP</span><span class="plain-syntax">), </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">, </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">, </span><span class="identifier-syntax">Inter_identifier</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">RTProperties::dont_show_in_index</span><span class="plain-syntax">(</span><span class="identifier-syntax">prn</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="named-paragraph-container code-font"><a href="3-vp.html#SP4_1" class="named-paragraph-link"><span class="named-paragraph">Initialise this nameless property</span><span class="named-paragraph-number">4.1</span></a></span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">prn</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
<span class="reserved-syntax">property</span><span class="plain-syntax"> *</span><span class="function-syntax">ValueProperties::new_nameless_using</span><span class="plain-syntax">(</span><span class="identifier-syntax">kind</span><span class="plain-syntax"> *</span><span class="identifier-syntax">K</span><span class="plain-syntax">, </span><span class="identifier-syntax">package_request</span><span class="plain-syntax"> *</span><span class="identifier-syntax">R</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">inter_name</span><span class="plain-syntax"> *</span><span class="identifier-syntax">using</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">K</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) </span><span class="identifier-syntax">internal_error</span><span class="plain-syntax">(</span><span class="string-syntax">"new nameless property without kind"</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">package_request</span><span class="plain-syntax"> *</span><span class="identifier-syntax">PR</span><span class="plain-syntax"> = </span><span class="identifier-syntax">Hierarchy::package_within</span><span class="plain-syntax">(</span><span class="identifier-syntax">KIND_PROPERTIES_HAP</span><span class="plain-syntax">, </span><span class="identifier-syntax">R</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">property</span><span class="plain-syntax"> *</span><span class="identifier-syntax">prn</span><span class="plain-syntax"> = </span><a href="3-prp.html#SP3" class="function-link"><span class="function-syntax">Properties::create</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">EMPTY_WORDING</span><span class="plain-syntax">, </span><span class="identifier-syntax">PR</span><span class="plain-syntax">, </span><span class="identifier-syntax">using</span><span class="plain-syntax">, </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">, </span><span class="identifier-syntax">InterNames::to_text</span><span class="plain-syntax">(</span><span class="identifier-syntax">using</span><span class="plain-syntax">));</span>
<span class="plain-syntax"> </span><span class="named-paragraph-container code-font"><a href="3-vp.html#SP4_1" class="named-paragraph-link"><span class="named-paragraph">Initialise this nameless property</span><span class="named-paragraph-number">4.1</span></a></span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">prn</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP4_1" class="paragraph-anchor"></a><b>&#167;4.1. </b><span class="named-paragraph-container code-font"><span class="named-paragraph-defn">Initialise this nameless property</span><span class="named-paragraph-number">4.1</span></span><span class="comment-syntax"> =</span>
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="plain-syntax"> </span><span class="identifier-syntax">RTProperties::dont_show_in_index</span><span class="plain-syntax">(</span><span class="identifier-syntax">prn</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">prn</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">value_data</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">property_value_kind</span><span class="plain-syntax"> = </span><span class="identifier-syntax">K</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">prn</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">value_data</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">setting_bp</span><span class="plain-syntax"> =</span>
<span class="plain-syntax"> </span><a href="3-spr2.html#SP7" class="function-link"><span class="function-syntax">SettingPropertyRelations::make_set_nameless_property_BP</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">prn</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">prn</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">Inter_level_only</span><span class="plain-syntax"> = </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">;</span>
</pre>
<ul class="endnotetexts"><li>This code is used in <a href="3-vp.html#SP4">&#167;4</a> (twice).</li></ul>
<p class="commentary firstcommentary"><a id="SP5" class="paragraph-anchor"></a><b>&#167;5. The setting relation. </b>Every valued property has an associated relation to set it: i.e., where
asserting this relation is the same as asserting that the property value for
term 1 is set to term 2.
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">ValueProperties::make_setting_bp</span><button class="popup" onclick="togglePopup('usagePopup4')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup4">Usage of <span class="code-font"><span class="function-syntax">ValueProperties::make_setting_bp</span></span>:<br/>Properties - <a href="3-prp.html#SP2">&#167;2</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">property</span><span class="plain-syntax"> *</span><span class="identifier-syntax">prn</span><span class="plain-syntax">, </span><span class="identifier-syntax">wording</span><span class="plain-syntax"> </span><span class="identifier-syntax">W</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> ((</span><span class="identifier-syntax">prn</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) || (</span><span class="identifier-syntax">prn</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">either_or_data</span><span class="plain-syntax">)) </span><span class="identifier-syntax">internal_error</span><span class="plain-syntax">(</span><span class="string-syntax">"non-value property"</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">binary_predicate</span><span class="plain-syntax"> *</span><span class="identifier-syntax">bp</span><span class="plain-syntax"> = </span><a href="3-spr2.html#SP4" class="function-link"><span class="function-syntax">SettingPropertyRelations::find_set_property_BP</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">W</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">bp</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) </span><span class="identifier-syntax">bp</span><span class="plain-syntax"> = </span><a href="3-spr2.html#SP3" class="function-link"><span class="function-syntax">SettingPropertyRelations::make_set_property_BP</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">W</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><a href="3-spr2.html#SP5" class="function-link"><span class="function-syntax">SettingPropertyRelations::fix_property_bp</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">bp</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><a href="3-spr2.html#SP5" class="function-link"><span class="function-syntax">SettingPropertyRelations::fix_property_bp</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">BinaryPredicates::get_reversal</span><span class="plain-syntax">(</span><span class="identifier-syntax">bp</span><span class="plain-syntax">));</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">prn</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">value_data</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">setting_bp</span><span class="plain-syntax"> = </span><span class="identifier-syntax">bp</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
<span class="identifier-syntax">binary_predicate</span><span class="plain-syntax"> *</span><span class="function-syntax">ValueProperties::get_setting_bp</span><span class="plain-syntax">(</span><span class="reserved-syntax">property</span><span class="plain-syntax"> *</span><span class="identifier-syntax">prn</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> ((</span><span class="identifier-syntax">prn</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) || (</span><span class="identifier-syntax">prn</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">either_or_data</span><span class="plain-syntax">)) </span><span class="identifier-syntax">internal_error</span><span class="plain-syntax">(</span><span class="string-syntax">"non-value property"</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">prn</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">value_data</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">setting_bp</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP6" class="paragraph-anchor"></a><b>&#167;6. Details. </b>The most important fact about a valued property is what kind of value it holds:
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="identifier-syntax">kind</span><span class="plain-syntax"> *</span><span class="function-syntax">ValueProperties::kind</span><button class="popup" onclick="togglePopup('usagePopup5')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup5">Usage of <span class="code-font"><span class="function-syntax">ValueProperties::kind</span></span>:<br/>Instances - <a href="2-ins.html#SP8">&#167;8</a><br/>Properties - <a href="3-prp.html#SP14">&#167;14</a>, <a href="3-prp.html#SP18">&#167;18</a><br/>Setting Property Relation - <a href="3-spr2.html#SP8">&#167;8</a>, <a href="3-spr2.html#SP9">&#167;9</a><br/>Measurements - <a href="3-msr.html#SP9_2">&#167;9.2</a><br/>Property Inferences - <a href="5-pi.html#SP12">&#167;12</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">property</span><span class="plain-syntax"> *</span><span class="identifier-syntax">prn</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> ((</span><span class="identifier-syntax">prn</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) || (</span><span class="identifier-syntax">prn</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">either_or_data</span><span class="plain-syntax">)) </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">; </span><span class="comment-syntax"> for better type-checking Problems</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">prn</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">value_data</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">property_value_kind</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">ValueProperties::set_kind</span><button class="popup" onclick="togglePopup('usagePopup6')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup6">Usage of <span class="code-font"><span class="function-syntax">ValueProperties::set_kind</span></span>:<br/><a href="3-vp.html#SP7">&#167;7</a><br/>Properties - <a href="3-prp.html#SP3_7">&#167;3.7</a><br/>Kind Subjects - <a href="4-ks.html#SP11">&#167;11</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">property</span><span class="plain-syntax"> *</span><span class="identifier-syntax">prn</span><span class="plain-syntax">, </span><span class="identifier-syntax">kind</span><span class="plain-syntax"> *</span><span class="identifier-syntax">K</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">K</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) </span><span class="identifier-syntax">internal_error</span><span class="plain-syntax">(</span><span class="string-syntax">"tried to set null kind"</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> ((</span><span class="identifier-syntax">prn</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) || (</span><span class="identifier-syntax">prn</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">either_or_data</span><span class="plain-syntax">)) </span><span class="identifier-syntax">internal_error</span><span class="plain-syntax">(</span><span class="string-syntax">"non-value property"</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> ((</span><span class="identifier-syntax">Kinds::Behaviour::definite</span><span class="plain-syntax">(</span><span class="identifier-syntax">K</span><span class="plain-syntax">) == </span><span class="identifier-syntax">FALSE</span><span class="plain-syntax">) &amp;&amp; (</span><span class="identifier-syntax">RTProperties::can_be_compiled</span><span class="plain-syntax">(</span><span class="identifier-syntax">prn</span><span class="plain-syntax">))) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Problems::quote_wording</span><span class="plain-syntax">(1, </span><span class="identifier-syntax">prn</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">name</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Problems::quote_kind</span><span class="plain-syntax">(2, </span><span class="identifier-syntax">K</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">StandardProblems::handmade_problem</span><span class="plain-syntax">(</span><span class="identifier-syntax">Task::syntax_tree</span><span class="plain-syntax">(),</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">_p_</span><span class="plain-syntax">(</span><span class="identifier-syntax">PM_PropertyIndefinite</span><span class="plain-syntax">));</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">current_sentence</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Problems::quote_source</span><span class="plain-syntax">(3, </span><span class="identifier-syntax">current_sentence</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Problems::issue_problem_segment</span><span class="plain-syntax">(</span>
<span class="plain-syntax"> </span><span class="string-syntax">"In the sentence %3, I am unable to create the property '%1', because "</span>
<span class="plain-syntax"> </span><span class="string-syntax">"it has too vague a kind ('%2'). I need to know exactly what kind of "</span>
<span class="plain-syntax"> </span><span class="string-syntax">"value goes into each property: for instance, it's not enough to say "</span>
<span class="plain-syntax"> </span><span class="string-syntax">"'A door has a list of values called the access list', because I don't "</span>
<span class="plain-syntax"> </span><span class="string-syntax">"know what the entries in this list would have to be - 'A door has a "</span>
<span class="plain-syntax"> </span><span class="string-syntax">"list of people called the access list' would be better."</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> } </span><span class="reserved-syntax">else</span><span class="plain-syntax"> {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Problems::issue_problem_segment</span><span class="plain-syntax">(</span>
<span class="plain-syntax"> </span><span class="string-syntax">"I am unable to create the property '%1', because it has too vague "</span>
<span class="plain-syntax"> </span><span class="string-syntax">"a kind ('%2'). I need to know exactly what kind of value goes into each "</span>
<span class="plain-syntax"> </span><span class="string-syntax">"property: for instance, it's not enough to say 'A door has a list of "</span>
<span class="plain-syntax"> </span><span class="string-syntax">"values called the access list', because I don't know what the entries "</span>
<span class="plain-syntax"> </span><span class="string-syntax">"in this list would have to be - 'A door has a list of people called the "</span>
<span class="plain-syntax"> </span><span class="string-syntax">"access list' would be better."</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">Problems::issue_problem_end</span><span class="plain-syntax">();</span>
<span class="plain-syntax"> }</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">prn</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">value_data</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">property_value_kind</span><span class="plain-syntax"> = </span><span class="identifier-syntax">K</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP7" class="paragraph-anchor"></a><b>&#167;7. Coincidence. </b>Sometimes the name of a property is the same as that of a kind of value. For
instance, we might define a kind of value called "weight", and then say that a
thing has a weight: that makes a property also called "weight", which is a
value property whose value is always a weight.
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">ValueProperties::make_coincide_with_kind</span><button class="popup" onclick="togglePopup('usagePopup7')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup7">Usage of <span class="code-font"><span class="function-syntax">ValueProperties::make_coincide_with_kind</span></span>:<br/>Properties - <a href="3-prp.html#SP3_4">&#167;3.4</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">property</span><span class="plain-syntax"> *</span><span class="identifier-syntax">prn</span><span class="plain-syntax">, </span><span class="identifier-syntax">kind</span><span class="plain-syntax"> *</span><span class="identifier-syntax">K</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> ((</span><span class="identifier-syntax">prn</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) || (</span><span class="identifier-syntax">prn</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">either_or_data</span><span class="plain-syntax">)) </span><span class="identifier-syntax">internal_error</span><span class="plain-syntax">(</span><span class="string-syntax">"non-value property"</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><a href="3-vp.html#SP6" class="function-link"><span class="function-syntax">ValueProperties::set_kind</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">prn</span><span class="plain-syntax">, </span><span class="identifier-syntax">K</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><span class="identifier-syntax">Kinds::eq</span><span class="plain-syntax">(</span><span class="identifier-syntax">K</span><span class="plain-syntax">, </span><span class="identifier-syntax">K_grammatical_gender</span><span class="plain-syntax">)) </span><span class="identifier-syntax">P_grammatical_gender</span><span class="plain-syntax"> = </span><span class="identifier-syntax">prn</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">prn</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">value_data</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">name_coincides_with_kind</span><span class="plain-syntax"> = </span><span class="identifier-syntax">TRUE</span><span class="plain-syntax">;</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> (</span><a href="3-prp.html#SP19" class="function-link"><span class="function-syntax">Properties::can_name_coincide_with_kind</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">K</span><span class="plain-syntax">))</span>
<span class="plain-syntax"> </span><a href="2-ins.html#SP7" class="function-link"><span class="function-syntax">Instances::make_kind_coincident</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">K</span><span class="plain-syntax">, </span><span class="identifier-syntax">prn</span><span class="plain-syntax">);</span>
<span class="plain-syntax">}</span>
<span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="function-syntax">ValueProperties::coincides_with_kind</span><span class="plain-syntax">(</span><span class="reserved-syntax">property</span><span class="plain-syntax"> *</span><span class="identifier-syntax">prn</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> ((</span><span class="identifier-syntax">prn</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) || (</span><span class="identifier-syntax">prn</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">either_or_data</span><span class="plain-syntax">)) </span><span class="identifier-syntax">internal_error</span><span class="plain-syntax">(</span><span class="string-syntax">"non-value property"</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">prn</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">value_data</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">name_coincides_with_kind</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP8" class="paragraph-anchor"></a><b>&#167;8. Storing relations. </b>Some value properties are used for relation storage at run-time:
</p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">ValueProperties::set_stored_relation</span><span class="plain-syntax">(</span><span class="reserved-syntax">property</span><span class="plain-syntax"> *</span><span class="identifier-syntax">prn</span><span class="plain-syntax">, </span><span class="identifier-syntax">binary_predicate</span><span class="plain-syntax"> *</span><span class="identifier-syntax">bp</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> ((</span><span class="identifier-syntax">prn</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) || (</span><span class="identifier-syntax">prn</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">either_or_data</span><span class="plain-syntax">)) </span><span class="identifier-syntax">internal_error</span><span class="plain-syntax">(</span><span class="string-syntax">"non-value property"</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">prn</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">value_data</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">relation_whose_state_this_stores</span><span class="plain-syntax"> = </span><span class="identifier-syntax">bp</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
<span class="identifier-syntax">binary_predicate</span><span class="plain-syntax"> *</span><span class="function-syntax">ValueProperties::get_stored_relation</span><button class="popup" onclick="togglePopup('usagePopup8')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup8">Usage of <span class="code-font"><span class="function-syntax">ValueProperties::get_stored_relation</span></span>:<br/>Property Inferences - <a href="5-pi.html#SP6">&#167;6</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">property</span><span class="plain-syntax"> *</span><span class="identifier-syntax">prn</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">if</span><span class="plain-syntax"> ((</span><span class="identifier-syntax">prn</span><span class="plain-syntax"> == </span><span class="identifier-syntax">NULL</span><span class="plain-syntax">) || (</span><span class="identifier-syntax">prn</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">either_or_data</span><span class="plain-syntax">)) </span><span class="identifier-syntax">internal_error</span><span class="plain-syntax">(</span><span class="string-syntax">"non-value property"</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><span class="reserved-syntax">return</span><span class="plain-syntax"> </span><span class="identifier-syntax">prn</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">value_data</span><span class="plain-syntax">-&gt;</span><span class="element-syntax">relation_whose_state_this_stores</span><span class="plain-syntax">;</span>
<span class="plain-syntax">}</span>
</pre>
<p class="commentary firstcommentary"><a id="SP9" class="paragraph-anchor"></a><b>&#167;9. Assertion. </b></p>
<pre class="displayed-code all-displayed-code code-font">
<span class="reserved-syntax">void</span><span class="plain-syntax"> </span><span class="function-syntax">ValueProperties::assert</span><button class="popup" onclick="togglePopup('usagePopup9')"><span class="comment-syntax">?</span><span class="popuptext" id="usagePopup9">Usage of <span class="code-font"><span class="function-syntax">ValueProperties::assert</span></span>:<br/>Indefinite Appearance - <a href="5-ia.html#SP1">&#167;1</a>, <a href="5-ia.html#SP2">&#167;2</a><br/>The Model World - <a href="5-tmw.html#SP3">&#167;3</a><br/>The Naming Thicket - <a href="5-tnt.html#SP6">&#167;6</a>, <a href="5-tnt.html#SP7">&#167;7</a>, <a href="5-tnt.html#SP9_1_2_1">&#167;9.1.2.1</a>, <a href="5-tnt.html#SP9_1_2_2">&#167;9.1.2.2</a>, <a href="5-tnt.html#SP9_1_3">&#167;9.1.3</a></span></button><span class="plain-syntax">(</span><span class="reserved-syntax">property</span><span class="plain-syntax"> *</span><span class="identifier-syntax">prn</span><span class="plain-syntax">, </span><span class="reserved-syntax">inference_subject</span><span class="plain-syntax"> *</span><span class="identifier-syntax">owner</span><span class="plain-syntax">,</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">parse_node</span><span class="plain-syntax"> *</span><span class="identifier-syntax">val</span><span class="plain-syntax">, </span><span class="reserved-syntax">int</span><span class="plain-syntax"> </span><span class="identifier-syntax">certainty</span><span class="plain-syntax">) {</span>
<span class="plain-syntax"> </span><span class="identifier-syntax">pcalc_prop</span><span class="plain-syntax"> *</span><span class="identifier-syntax">prop</span><span class="plain-syntax"> = </span><span class="identifier-syntax">Propositions::Abstract::to_set_property</span><span class="plain-syntax">(</span><span class="identifier-syntax">prn</span><span class="plain-syntax">, </span><span class="identifier-syntax">val</span><span class="plain-syntax">);</span>
<span class="plain-syntax"> </span><a href="1-ap.html#SP2" class="function-link"><span class="function-syntax">Assert::true_about</span></a><span class="plain-syntax">(</span><span class="identifier-syntax">prop</span><span class="plain-syntax">, </span><span class="identifier-syntax">owner</span><span class="plain-syntax">, </span><span class="identifier-syntax">certainty</span><span class="plain-syntax">);</span>
<span class="plain-syntax">}</span>
</pre>
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