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diff --git a/devdocs/elisp/symbol-plists.html b/devdocs/elisp/symbol-plists.html new file mode 100644 index 00000000..e0cfb30b --- /dev/null +++ b/devdocs/elisp/symbol-plists.html @@ -0,0 +1,40 @@ + <h4 class="subsection">Accessing Symbol Properties</h4> <p>The following functions can be used to access symbol properties. </p> <dl> <dt id="get">Function: <strong>get</strong> <em>symbol property</em> +</dt> <dd> +<p>This function returns the value of the property named <var>property</var> in <var>symbol</var>’s property list. If there is no such property, it returns <code>nil</code>. Thus, there is no distinction between a value of <code>nil</code> and the absence of the property. </p> <p>The name <var>property</var> is compared with the existing property names using <code>eq</code>, so any object is a legitimate property. </p> <p>See <code>put</code> for an example. </p> +</dd> +</dl> <dl> <dt id="put">Function: <strong>put</strong> <em>symbol property value</em> +</dt> <dd> +<p>This function puts <var>value</var> onto <var>symbol</var>’s property list under the property name <var>property</var>, replacing any previous property value. The <code>put</code> function returns <var>value</var>. </p> <div class="example"> <pre class="example">(put 'fly 'verb 'transitive) + ⇒'transitive +(put 'fly 'noun '(a buzzing little bug)) + ⇒ (a buzzing little bug) +(get 'fly 'verb) + ⇒ transitive +(symbol-plist 'fly) + ⇒ (verb transitive noun (a buzzing little bug)) +</pre> +</div> </dd> +</dl> <dl> <dt id="symbol-plist">Function: <strong>symbol-plist</strong> <em>symbol</em> +</dt> <dd><p>This function returns the property list of <var>symbol</var>. </p></dd> +</dl> <dl> <dt id="setplist">Function: <strong>setplist</strong> <em>symbol plist</em> +</dt> <dd> +<p>This function sets <var>symbol</var>’s property list to <var>plist</var>. Normally, <var>plist</var> should be a well-formed property list, but this is not enforced. The return value is <var>plist</var>. </p> <div class="example"> <pre class="example">(setplist 'foo '(a 1 b (2 3) c nil)) + ⇒ (a 1 b (2 3) c nil) +(symbol-plist 'foo) + ⇒ (a 1 b (2 3) c nil) +</pre> +</div> <p>For symbols in special obarrays, which are not used for ordinary purposes, it may make sense to use the property list cell in a nonstandard fashion; in fact, the abbrev mechanism does so (see <a href="abbrevs">Abbrevs</a>). </p> <p>You could define <code>put</code> in terms of <code>setplist</code> and <code>plist-put</code>, as follows: </p> <div class="example"> <pre class="example">(defun put (symbol prop value) + (setplist symbol + (plist-put (symbol-plist symbol) prop value))) +</pre> +</div> </dd> +</dl> <dl> <dt id="function-get">Function: <strong>function-get</strong> <em>symbol property &optional autoload</em> +</dt> <dd><p>This function is identical to <code>get</code>, except that if <var>symbol</var> is the name of a function alias, it looks in the property list of the symbol naming the actual function. See <a href="defining-functions">Defining Functions</a>. If the optional argument <var>autoload</var> is non-<code>nil</code>, and <var>symbol</var> is auto-loaded, this function will try to autoload it, since autoloading might set <var>property</var> of <var>symbol</var>. If <var>autoload</var> is the symbol <code>macro</code>, only try autoloading if <var>symbol</var> is an auto-loaded macro. </p></dd> +</dl> <dl> <dt id="function-put">Function: <strong>function-put</strong> <em>function property value</em> +</dt> <dd><p>This function sets <var>property</var> of <var>function</var> to <var>value</var>. <var>function</var> should be a symbol. This function is preferred to calling <code>put</code> for setting properties of a function, because it will allow us some day to implement remapping of old properties to new ones. </p></dd> +</dl><div class="_attribution"> + <p class="_attribution-p"> + Copyright © 1990-1996, 1998-2022 Free Software Foundation, Inc. <br>Licensed under the GNU GPL license.<br> + <a href="https://www.gnu.org/software/emacs/manual/html_node/elisp/Symbol-Plists.html" class="_attribution-link">https://www.gnu.org/software/emacs/manual/html_node/elisp/Symbol-Plists.html</a> + </p> +</div> |