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docSidebarContainer_YfHR"><div class="sidebarViewport_aRkj"><div class="sidebar_njMd"><nav aria-label="Docs sidebar" class="menu thin-scrollbar menu_SIkG"><ul class="theme-doc-sidebar-menu menu__list"><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-1 menu__list-item"><a class="menu__link" href="../../index.html">Introduction</a></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-1 menu__list-item menu__list-item--collapsed"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist menu__link--sublist-caret" aria-expanded="false" href="../../chap-0/intro.html">Contents and Figures</a></div></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-1 menu__list-item menu__list-item--collapsed"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist menu__link--sublist-caret" aria-expanded="false" href="../../chap-1/b-b-scope-purpose-and-history.html">1. Introduction</a></div></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-1 menu__list-item menu__list-item--collapsed"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist menu__link--sublist-caret" aria-expanded="false" href="../../chap-2/c-b-character-syntax.html">2. Syntax</a></div></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-1 menu__list-item menu__list-item--collapsed"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist menu__link--sublist-caret" aria-expanded="false" href="../../chap-3/d-b-evaluation.html">3. Evaluation and Compilation</a></div></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-1 menu__list-item menu__list-item--collapsed"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist menu__link--sublist-caret" aria-expanded="false" href="../../chap-4/e-b-introduction.html">4. Types and Classes</a></div></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-1 menu__list-item menu__list-item--collapsed"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist menu__link--sublist-caret" aria-expanded="false" href="../../chap-5/f-b-generalized-reference.html">5. Data and Control Flow</a></div></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-1 menu__list-item menu__list-item--collapsed"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist menu__link--sublist-caret" aria-expanded="false" href="../../chap-6/g-b-the-loop-facility.html">6. Iteration</a></div></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-1 menu__list-item menu__list-item--collapsed"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist menu__link--sublist-caret" aria-expanded="false" href="../../chap-7/h-b-object-creation-and-initialization.html">7. Objects</a></div></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-1 menu__list-item menu__list-item--collapsed"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist menu__link--sublist-caret" aria-expanded="false" href="../../category/81-structures-dictionary.html">8. Structures</a></div></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-1 menu__list-item menu__list-item--collapsed"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist menu__link--sublist-caret" aria-expanded="false" href="../../chap-9/j-b-condition-system-concepts.html">9. Conditions</a></div></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-1 menu__list-item menu__list-item--collapsed"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist menu__link--sublist-caret" aria-expanded="false" href="../../chap-10/ba-b-symbol-concepts.html">10. Symbols</a></div></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-1 menu__list-item menu__list-item--collapsed"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist menu__link--sublist-caret" aria-expanded="false" href="../../chap-11/bb-b-package-concepts.html">11. Packages</a></div></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-1 menu__list-item menu__list-item--collapsed"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist menu__link--sublist-caret" aria-expanded="false" href="../../chap-12/bc-b-number-concepts.html">12. Numbers</a></div></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-1 menu__list-item menu__list-item--collapsed"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist menu__link--sublist-caret" aria-expanded="false" href="../../chap-13/bd-b-character-concepts.html">13. Characters</a></div></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-1 menu__list-item menu__list-item--collapsed"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist menu__link--sublist-caret" aria-expanded="false" href="../../chap-14/be-b-cons-concepts.html">14. Conses</a></div></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-1 menu__list-item menu__list-item--collapsed"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist menu__link--sublist-caret" aria-expanded="false" href="../../chap-15/bf-b-array-concepts.html">15. Arrays</a></div></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-1 menu__list-item menu__list-item--collapsed"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist menu__link--sublist-caret" aria-expanded="false" href="../../chap-16/bg-b-string-concepts.html">16. Strings</a></div></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-1 menu__list-item menu__list-item--collapsed"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist menu__link--sublist-caret" aria-expanded="false" href="../../chap-17/bh-b-sequence-concepts.html">17. Sequences</a></div></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-1 menu__list-item menu__list-item--collapsed"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist menu__link--sublist-caret" aria-expanded="false" href="../../chap-18/bi-b-hash-table-concepts.html">18. Hash Tables</a></div></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-1 menu__list-item menu__list-item--collapsed"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist menu__link--sublist-caret" aria-expanded="false" href="../../chap-19/bj-b-overview-of-filenames.html">19. Filenames</a></div></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-1 menu__list-item menu__list-item--collapsed"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist menu__link--sublist-caret" aria-expanded="false" href="../../chap-20/ca-b-file-system-concepts.html">20. Files</a></div></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-1 menu__list-item menu__list-item--collapsed"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist menu__link--sublist-caret" aria-expanded="false" href="../../chap-21/cb-b-stream-concepts.html">21. Streams</a></div></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-1 menu__list-item menu__list-item--collapsed"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist menu__link--sublist-caret" aria-expanded="false" href="../../chap-22/cc-b-the-lisp-printer.html">22. Printer</a></div></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-1 menu__list-item menu__list-item--collapsed"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist menu__link--sublist-caret" aria-expanded="false" href="../../chap-23/cd-b-reader-concepts.html">23. Reader</a></div></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-1 menu__list-item menu__list-item--collapsed"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist menu__link--sublist-caret" aria-expanded="false" href="../../chap-24/ce-b-system-construction-concepts.html">24. System Construction</a></div></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-1 menu__list-item menu__list-item--collapsed"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist menu__link--sublist-caret" aria-expanded="false" href="../../chap-25/cf-b-the-external-environment.html">25. External Environment</a></div></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-1 menu__list-item menu__list-item--collapsed"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist menu__link--sublist-caret" aria-expanded="false" href="../../environments.html">26. Environments</a></div></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-1 menu__list-item"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist menu__link--sublist-caret menu__link--active" aria-expanded="true" href="../../meta-object-protocol.html">27. Meta Object Protocol</a></div><ul style="display:block;overflow:visible;height:auto" class="menu__list"><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-2 menu__list-item"><a class="menu__link" tabindex="0" href="../../meta-object-protocol.html">Meta Object Protocol Introduction</a></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-2 menu__list-item"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist menu__link--active" aria-expanded="true" tabindex="0" href="../../category/chapter-5---concepts.html">Chapter 5 - Concepts</a><button aria-label="Collapse sidebar category 'Chapter 5 - Concepts'" type="button" class="clean-btn menu__caret"></button></div><ul style="display:block;overflow:visible;height:auto" class="menu__list"><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-3 menu__list-item"><a class="menu__link" tabindex="0" href="introduction.html">5.1 Introduction</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-3 menu__list-item"><a class="menu__link menu__link--active" aria-current="page" tabindex="0" href="5-2-metaobjects.html">5.2 Metaobjects</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-3 menu__list-item"><a class="menu__link" tabindex="0" href="5-3-inheritance.html">5.3 Inheritance Structure Of Metaobject Classes</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-3 menu__list-item"><a class="menu__link" tabindex="0" href="5-4-processing.html">5.4 Processing Of The User Interface Macros</a></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-3 menu__list-item"><a class="menu__link" tabindex="0" href="5-5-subprotocols.html">5.5 Subprotocols</a></li></ul></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-2 menu__list-item menu__list-item--collapsed"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist" aria-expanded="false" tabindex="0" href="../../category/chapter-6---generic-functions-and-methods.html">Chapter 6 - Generic Functions and Methods</a><button aria-label="Expand sidebar category 'Chapter 6 - Generic Functions and Methods'" type="button" class="clean-btn menu__caret"></button></div></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-2 menu__list-item menu__list-item--collapsed"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist" aria-expanded="false" tabindex="0" href="../../category/additional-material.html">Additional Material</a><button aria-label="Expand sidebar category 'Additional Material'" type="button" class="clean-btn menu__caret"></button></div></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-2 menu__list-item menu__list-item--collapsed"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist" aria-expanded="false" tabindex="0" href="../../category/mop-dictionary.html">MOP Dictionary</a><button aria-label="Expand sidebar category 'MOP Dictionary'" type="button" class="clean-btn menu__caret"></button></div></li></ul></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-1 menu__list-item menu__list-item--collapsed"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist menu__link--sublist-caret" aria-expanded="false" href="../../data-structures.html">28. Data Structures</a></div></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-1 menu__list-item menu__list-item--collapsed"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist menu__link--sublist-caret" aria-expanded="false" href="../../portability/trivial-packages.html">29. Portability</a></div></li><li class="theme-doc-sidebar-item-link theme-doc-sidebar-item-link-level-1 menu__list-item"><a class="menu__link" href="../../dictionary-entries.html">dictionary-entries</a></li><li class="theme-doc-sidebar-item-category theme-doc-sidebar-item-category-level-1 menu__list-item menu__list-item--collapsed"><div class="menu__list-item-collapsible"><a class="menu__link menu__link--sublist menu__link--sublist-caret" aria-expanded="false" href="../../chap-26/intro.html">Glossary</a></div></li></ul></nav></div></div></aside><main class="docMainContainer_TBSr"><div class="container padding-top--md padding-bottom--lg"><div class="row"><div class="col docItemCol_VOVn"><div class="docItemContainer_Djhp"><article><nav class="theme-doc-breadcrumbs breadcrumbsContainer_Z_bl" aria-label="Breadcrumbs"><ul class="breadcrumbs" itemscope="" itemtype="https://schema.org/BreadcrumbList"><li class="breadcrumbs__item"><a aria-label="Home page" class="breadcrumbs__link" href="../../index.html"><svg viewBox="0 0 24 24" class="breadcrumbHomeIcon_YNFT"><path d="M10 19v-5h4v5c0 .55.45 1 1 1h3c.55 0 1-.45 1-1v-7h1.7c.46 0 .68-.57.33-.87L12.67 3.6c-.38-.34-.96-.34-1.34 0l-8.36 7.53c-.34.3-.13.87.33.87H5v7c0 .55.45 1 1 1h3c.55 0 1-.45 1-1z" fill="currentColor"></path></svg></a></li><li class="breadcrumbs__item"><span class="breadcrumbs__link">27. Meta Object Protocol</span><meta itemprop="position" content="1"></li><li itemscope="" itemprop="itemListElement" itemtype="https://schema.org/ListItem" class="breadcrumbs__item"><a class="breadcrumbs__link" itemprop="item" href="../../category/chapter-5---concepts.html"><span itemprop="name">Chapter 5 - Concepts</span></a><meta itemprop="position" content="2"></li><li itemscope="" itemprop="itemListElement" itemtype="https://schema.org/ListItem" class="breadcrumbs__item breadcrumbs__item--active"><span class="breadcrumbs__link" itemprop="name">5.2 Metaobjects</span><meta itemprop="position" content="3"></li></ul></nav><div class="tocCollapsible_ETCw theme-doc-toc-mobile tocMobile_ITEo"><button type="button" class="clean-btn tocCollapsibleButton_TO0P">On this page</button></div><div class="theme-doc-markdown markdown"><h1>5.2 Metaobjects</h1>
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<!-- -->
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<h1>Metaobjects</h1>
|
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<h2 class="anchor anchorWithStickyNavbar_LWe7" id="metaobjects-1">Metaobjects<a href="5-2-metaobjects.html#metaobjects-1" class="hash-link" aria-label="Direct link to Metaobjects" title="Direct link to Metaobjects"></a></h2>
|
||
<p>For each kind of program element there is a corresponding <em>basic metaobject class</em>. These are the classes: <a href="https://lisp-docs.github.io/cl-language-reference/meta-object-protocol/class-class">class</a>, <a href="https://lisp-docs.github.io/cl-language-reference/meta-object-protocol/class-slot-definition">slot-definition</a>, <a href="https://lisp-docs.github.io/cl-language-reference/meta-object-protocol/class-generic-function">generic-function</a>, <a href="https://lisp-docs.github.io/cl-language-reference/meta-object-protocol/class-method">method</a>, and <a href="https://lisp-docs.github.io/cl-language-reference/meta-object-protocol/class-method-combination">method-combination</a>. A <em>metaobject class</em> is a subclass of exactly one of these classes. The results are undefined if an attempt is made to define a class that is a subclass of more than one basic metaobject class. A <em>metaobject</em> is an instance of a metaobject class.</p>
|
||
<p>Each metaobject represents one program element. Associated with each metaobject is the information required to serve its role. This includes information that might be provided directly in a user interface macro such as <a href="http://www.lispworks.com/documentation/HyperSpec/Body/m_defcla.htm#defclass" target="_blank" rel="noopener noreferrer">defclass</a> or <a href="http://www.lispworks.com/documentation/HyperSpec/Body/m_defcla.htm#defmethod" target="_blank" rel="noopener noreferrer">defmethod</a>. It also includes information computed indirectly from other metaobjects such as that computed from class inheritance or the full set of methods associated with a generic function.</p>
|
||
<p>Much of the information associated with a metaobject is in the form of connections to other metaobjects. This interconnection means that the role of a metaobject is always based on that of other metaobjects. As an introduction to this interconnected structure, this section presents a partial enumeration of the kinds of information associated with each kind of metaobject. More detailed information is presented later.</p>
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<ul>
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||
<li><a href="https://lisp-docs.github.io/cl-language-reference/meta-object-protocol/classes">Classes</a></li>
|
||
<li><a href="https://lisp-docs.github.io/cl-language-reference/meta-object-protocol/slot-definitions">Slot definitions</a></li>
|
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<li><a href="https://lisp-docs.github.io/cl-language-reference/meta-object-protocol/generic-functions">Generic functions</a></li>
|
||
<li><a href="https://lisp-docs.github.io/cl-language-reference/meta-object-protocol/methods">Methods</a></li>
|
||
<li><a href="https://lisp-docs.github.io/cl-language-reference/meta-object-protocol/specializers">Specializers</a></li>
|
||
<li><a href="https://lisp-docs.github.io/cl-language-reference/meta-object-protocol/method-combinations">Method combinations</a></li>
|
||
</ul>
|
||
<h2 class="anchor anchorWithStickyNavbar_LWe7" id="521-classes">5.2.1 Classes<a href="5-2-metaobjects.html#521-classes" class="hash-link" aria-label="Direct link to 5.2.1 Classes" title="Direct link to 5.2.1 Classes"></a></h2>
|
||
<!-- -->
|
||
<h1>Classes</h1>
|
||
<h3 class="anchor anchorWithStickyNavbar_LWe7" id="classes-1">Classes<a href="5-2-metaobjects.html#classes-1" class="hash-link" aria-label="Direct link to Classes" title="Direct link to Classes"></a></h3>
|
||
<p>A <em>class metaobject</em> determines the structure and the default behavior of its instances. The following information is associated with class metaobjects:</p>
|
||
<ul>
|
||
<li>
|
||
<p>The name, if there is one, is available as an object.</p>
|
||
</li>
|
||
<li>
|
||
<p>The direct subclasses, direct superclasses and class precedence list are available as lists of class metaobjects.</p>
|
||
</li>
|
||
<li>
|
||
<p>The slots defined directly in the class are available as a list of direct slot definition metaobjects. The slots which are accessible in instances of the class are available as a list of effective slot definition metaobjects.</p>
|
||
</li>
|
||
<li>
|
||
<p>The documentation is available as a string or <code>nil</code>.</p>
|
||
</li>
|
||
<li>
|
||
<p>The methods which use the class as a specializer, and the generic functions associated with those methods are available as lists of method and generic function metaobjects respectively.</p>
|
||
</li>
|
||
</ul>
|
||
<h2 class="anchor anchorWithStickyNavbar_LWe7" id="522-slot-definitions">5.2.2 Slot Definitions<a href="5-2-metaobjects.html#522-slot-definitions" class="hash-link" aria-label="Direct link to 5.2.2 Slot Definitions" title="Direct link to 5.2.2 Slot Definitions"></a></h2>
|
||
<!-- -->
|
||
<h1>Slot definitions</h1>
|
||
<h3 class="anchor anchorWithStickyNavbar_LWe7" id="slot-definitions-1">Slot definitions<a href="5-2-metaobjects.html#slot-definitions-1" class="hash-link" aria-label="Direct link to Slot definitions" title="Direct link to Slot definitions"></a></h3>
|
||
<p>A <em>slot definition metaobject</em> contains information about the definition of a slot. There are two kinds of slot definition metaobjects. A direct slot definition metaobject is used to represent the direct definition of a slot in a class. This corresponds roughly to the slot specifiers found in <a href="http://www.lispworks.com/documentation/HyperSpec/Body/m_defcla.htm#defclass" target="_blank" rel="noopener noreferrer">defclass</a> forms. An effective slot definition metaobject is used to represent information, including inherited information, about a slot which is accessible in instances of a particular class.</p>
|
||
<p>Associated with each class metaobject is a list of direct slot definition metaobjects representing the slots defined directly in the class. Also associated with each class metaobject is a list of effective slot definition metaobjects representing the set of slots accessible in instances of that class.</p>
|
||
<p>The following information is associated with both direct and effective slot definitions metaobjects:</p>
|
||
<ul>
|
||
<li>
|
||
<p>The name, allocation, and type are available as forms that could appear in a <a href="http://www.lispworks.com/documentation/HyperSpec/Body/m_defcla.htm#defclass" target="_blank" rel="noopener noreferrer">defclass</a> form.</p>
|
||
</li>
|
||
<li>
|
||
<p>The initialization form, if there is one, is available as a form that could appear in a <a href="http://www.lispworks.com/documentation/HyperSpec/Body/m_defcla.htm#defclass" target="_blank" rel="noopener noreferrer">defclass</a> form. The initialization form together with its lexical environment is available as a function of no arguments which, when called, returns the result of evaluating the initialization form in its lexical environment. This is called the <em>initfunction</em> of the slot.</p>
|
||
</li>
|
||
<li>
|
||
<p>The slot filling initialization arguments are available as a list of symbols.</p>
|
||
</li>
|
||
<li>
|
||
<p>The documentation is available as a string or <code>nil</code>.</p>
|
||
</li>
|
||
</ul>
|
||
<p>Certain other information is only associated with direct slot definition metaobjects. This information applies only to the direct definition of the slot in the class (it is not inherited).</p>
|
||
<ul>
|
||
<li>The function names of those generic functions for which there are automatically generated reader and writer methods. This information is available as lists of function names. Any accessors specified in the <a href="http://www.lispworks.com/documentation/HyperSpec/Body/m_defcla.htm#defclass" target="_blank" rel="noopener noreferrer">defclass</a> form are broken down into their equivalent readers and writers in the direct slot definition.</li>
|
||
</ul>
|
||
<p>Information, including inherited information, which applies to the definition of a slot in a particular class in which it is accessible is associated only with effective slot definition metaobjects.</p>
|
||
<ul>
|
||
<li>For certain slots, the location of the slot in instances of the class is available.</li>
|
||
</ul>
|
||
<h2 class="anchor anchorWithStickyNavbar_LWe7" id="523-generic-functions">5.2.3 Generic Functions<a href="5-2-metaobjects.html#523-generic-functions" class="hash-link" aria-label="Direct link to 5.2.3 Generic Functions" title="Direct link to 5.2.3 Generic Functions"></a></h2>
|
||
<!-- -->
|
||
<h1>Generic functions</h1>
|
||
<h3 class="anchor anchorWithStickyNavbar_LWe7" id="generic-functions-1">Generic functions<a href="5-2-metaobjects.html#generic-functions-1" class="hash-link" aria-label="Direct link to Generic functions" title="Direct link to Generic functions"></a></h3>
|
||
<p>A <em>generic function metaobject</em> contains information about a generic function over and above the information associated with each of the generic function's methods.</p>
|
||
<ul>
|
||
<li>
|
||
<p>The name is available as a function name.</p>
|
||
</li>
|
||
<li>
|
||
<p>The methods associated with the generic function are available as a list of method metaobjects.</p>
|
||
</li>
|
||
<li>
|
||
<p>The default class for this generic function's method metaobjects is available as a class metaobject.</p>
|
||
</li>
|
||
<li>
|
||
<p>The lambda list is available as a list.</p>
|
||
</li>
|
||
<li>
|
||
<p>The method combination is available as a method combination metaobject.</p>
|
||
</li>
|
||
<li>
|
||
<p>The documentation is available as a string or <code>nil</code>.</p>
|
||
</li>
|
||
<li>
|
||
<p>The argument precedence order is available as a permutation of those symbols from the lambda list which name the required arguments of the generic function.</p>
|
||
</li>
|
||
<li>
|
||
<p>The declarations are available as a list of declarations.</p>
|
||
<p>There is some ambiguity in Common Lisp about the terms used to identify the various parts of <a href="http://www.lispworks.com/documentation/HyperSpec/Body/s_declar.htm#declare" target="_blank" rel="noopener noreferrer">declare</a> special forms. In this document, the term <em>declaration</em> is used to refer to an object that could be an argument to a <a href="http://www.lispworks.com/documentation/HyperSpec/Body/s_declar.htm#declare" target="_blank" rel="noopener noreferrer">declare</a> special form. For example, in the special form <code>(declare (special *g1*))</code>, the list <code>(special *g1*)</code> is a declaration.</p>
|
||
</li>
|
||
</ul>
|
||
<h2 class="anchor anchorWithStickyNavbar_LWe7" id="524-methods">5.2.4 Methods<a href="5-2-metaobjects.html#524-methods" class="hash-link" aria-label="Direct link to 5.2.4 Methods" title="Direct link to 5.2.4 Methods"></a></h2>
|
||
<!-- -->
|
||
<h1>Methods</h1>
|
||
<h3 class="anchor anchorWithStickyNavbar_LWe7" id="methods-1">Methods<a href="5-2-metaobjects.html#methods-1" class="hash-link" aria-label="Direct link to Methods" title="Direct link to Methods"></a></h3>
|
||
<p>A <em>method metaobject</em> contains information about a specific method.</p>
|
||
<ul>
|
||
<li>
|
||
<p>The qualifiers are available as a list of of non-null atoms.</p>
|
||
</li>
|
||
<li>
|
||
<p>The lambda list is available as a list.</p>
|
||
</li>
|
||
<li>
|
||
<p>The specializers are available as a list of specializer metaobjects.</p>
|
||
</li>
|
||
<li>
|
||
<p>The function is available as a function. This function can be applied to arguments and a list of next methods using <a href="http://www.lispworks.com/documentation/HyperSpec/Body/f_apply.htm#apply" target="_blank" rel="noopener noreferrer">apply</a> or <a href="http://www.lispworks.com/documentation/HyperSpec/Body/f_funcal.htm#funcall" target="_blank" rel="noopener noreferrer">funcall</a>.</p>
|
||
</li>
|
||
<li>
|
||
<p>When the method is associated with a generic function, that generic function metaobject is available. A method can be associated with at most one generic function at a time.</p>
|
||
</li>
|
||
<li>
|
||
<p>The documentation is available as a string or <code>nil</code>.</p>
|
||
</li>
|
||
</ul>
|
||
<h2 class="anchor anchorWithStickyNavbar_LWe7" id="525-specializers">5.2.5 Specializers<a href="5-2-metaobjects.html#525-specializers" class="hash-link" aria-label="Direct link to 5.2.5 Specializers" title="Direct link to 5.2.5 Specializers"></a></h2>
|
||
<!-- -->
|
||
<h1>Specializers</h1>
|
||
<h3 class="anchor anchorWithStickyNavbar_LWe7" id="specializers-1">Specializers<a href="5-2-metaobjects.html#specializers-1" class="hash-link" aria-label="Direct link to Specializers" title="Direct link to Specializers"></a></h3>
|
||
<p>A specializer metaobject represents the specializers of a method. Class metaobjects are themselves specializer metaobjects. A special kind of specializer metaobject is used for <code>eql</code> specializers.</p>
|
||
<h2 class="anchor anchorWithStickyNavbar_LWe7" id="526-method-combinations">5.2.6 Method Combinations<a href="5-2-metaobjects.html#526-method-combinations" class="hash-link" aria-label="Direct link to 5.2.6 Method Combinations" title="Direct link to 5.2.6 Method Combinations"></a></h2>
|
||
<!-- -->
|
||
<!-- -->
|
||
<h1>Method combinations</h1>
|
||
<h3 class="anchor anchorWithStickyNavbar_LWe7" id="method-combinations-1">Method combinations<a href="5-2-metaobjects.html#method-combinations-1" class="hash-link" aria-label="Direct link to Method combinations" title="Direct link to Method combinations"></a></h3>
|
||
<p>A <em>method combination metaobject</em> represents the information about the method combination being used by a generic function.</p>
|
||
<h4 class="anchor anchorWithStickyNavbar_LWe7" id="note">Note<a href="5-2-metaobjects.html#note" class="hash-link" aria-label="Direct link to Note" title="Direct link to Note"></a></h4>
|
||
<p>This document does not specify the structure of method combination metaobjects.</p></div><footer class="theme-doc-footer docusaurus-mt-lg"><div class="theme-doc-footer-edit-meta-row row"><div class="col"><a href="https://github.com/lisp-docs/cl-language-reference/tree/main/docs/meta-object-protocol/chap-5/5-2-metaobjects.md" target="_blank" rel="noopener noreferrer" class="theme-edit-this-page"><svg fill="currentColor" height="20" width="20" viewBox="0 0 40 40" class="iconEdit_Z9Sw" aria-hidden="true"><g><path d="m34.5 11.7l-3 3.1-6.3-6.3 3.1-3q0.5-0.5 1.2-0.5t1.1 0.5l3.9 3.9q0.5 0.4 0.5 1.1t-0.5 1.2z m-29.5 17.1l18.4-18.5 6.3 6.3-18.4 18.4h-6.3v-6.2z"></path></g></svg>Edit this page</a></div><div class="col lastUpdated_vwxv"><span class="theme-last-updated">Last updated<!-- --> by <b>daninus14</b></span></div></div></footer></article><nav class="pagination-nav docusaurus-mt-lg" aria-label="Docs pages"><a class="pagination-nav__link pagination-nav__link--prev" href="introduction.html"><div class="pagination-nav__sublabel">Previous</div><div class="pagination-nav__label">5.1 Introduction</div></a><a class="pagination-nav__link pagination-nav__link--next" href="5-3-inheritance.html"><div class="pagination-nav__sublabel">Next</div><div class="pagination-nav__label">5.3 Inheritance Structure Of Metaobject Classes</div></a></nav></div></div><div class="col col--3"><div class="tableOfContents_bqdL thin-scrollbar theme-doc-toc-desktop"><ul class="table-of-contents table-of-contents__left-border"><li><a href="5-2-metaobjects.html#521-classes" class="table-of-contents__link toc-highlight">5.2.1 Classes</a></li><li><a href="5-2-metaobjects.html#522-slot-definitions" class="table-of-contents__link toc-highlight">5.2.2 Slot Definitions</a></li><li><a href="5-2-metaobjects.html#523-generic-functions" class="table-of-contents__link toc-highlight">5.2.3 Generic Functions</a></li><li><a href="5-2-metaobjects.html#524-methods" class="table-of-contents__link toc-highlight">5.2.4 Methods</a></li><li><a href="5-2-metaobjects.html#525-specializers" class="table-of-contents__link toc-highlight">5.2.5 Specializers</a></li><li><a href="5-2-metaobjects.html#526-method-combinations" class="table-of-contents__link toc-highlight">5.2.6 Method Combinations</a></li></ul></div></div></div></div></main></div></div></div><footer class="footer footer--dark"><div class="container container-fluid"><div class="row footer__links"><div class="col footer__col"><div class="footer__title">Docs</div><ul class="footer__items clean-list"><li class="footer__item"><a href="../../../docs/tutorial.html" target="_blank" rel="noopener noreferrer" class="footer__link-item">Common Lisp Tutorial</a></li><li class="footer__item"><a href="../../index.html" target="_blank" rel="noopener noreferrer" class="footer__link-item">Common Lisp Technical Reference</a></li><li class="footer__item"><a href="../../../docs/help.html" target="_blank" rel="noopener noreferrer" 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