72 lines
3.6 KiB
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72 lines
3.6 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3O//DTD W3 HTML 2.0//EN">
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<!Converted with LaTeX2HTML 0.6.5 (Tue Nov 15 1994) by Nikos Drakos (nikos@cbl.leeds.ac.uk), CBLU, University of Leeds >
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<HEAD>
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<TITLE>28.1.2.1. Defining Classes</TITLE>
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<BODY>
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<meta name="description" value=" Defining Classes">
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<meta name="keywords" value="clm">
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<meta name="distribution" value="global">
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<P>
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<b>Common Lisp the Language, 2nd Edition</b>
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<BR> <HR><A NAME=tex2html4962 HREF="node265.html"><IMG ALIGN=BOTTOM ALT="next" SRC="icons/next_motif.gif"></A> <A NAME=tex2html4960 HREF="node263.html"><IMG ALIGN=BOTTOM ALT="up" SRC="icons/up_motif.gif"></A> <A NAME=tex2html4954 HREF="node263.html"><IMG ALIGN=BOTTOM ALT="previous" SRC="icons/previous_motif.gif"></A> <A NAME=tex2html4964 HREF="node1.html"><IMG ALIGN=BOTTOM ALT="contents" SRC="icons/contents_motif.gif"></A> <A NAME=tex2html4965 HREF="index.html"><IMG ALIGN=BOTTOM ALT="index" SRC="icons/index_motif.gif"></A> <BR>
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<B> Next:</B> <A NAME=tex2html4963 HREF="node265.html"> Creating Instances of </A>
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<B>Up:</B> <A NAME=tex2html4961 HREF="node263.html"> Classes</A>
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<B> Previous:</B> <A NAME=tex2html4955 HREF="node263.html"> Classes</A>
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<HR> <P>
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<H3><A NAME=SECTION003212100000000000000>28.1.2.1. Defining Classes</A></H3>
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<P>
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<img align=bottom alt="change_begin" src="gif/change_begin.gif"><br>
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The macro <tt>defclass</tt> is used to define a new named class.
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The definition of a class includes the following:
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<P>
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<UL><LI> The name of the new class. For newly defined classes
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this is a proper name.
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<P>
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<LI> The list of the direct superclasses of the new class.
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<P>
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<LI> A set of <i>slot specifiers</i>. Each slot specifier
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includes the name of the slot and zero or more <i>slot options</i>. A
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slot option pertains only to a single slot. If a class definition
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contains two slot specifiers with the same name, an error is signaled.
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<P>
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<LI> A set of <i>class options</i>. Each class option pertains
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to the class as a whole.
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</UL>
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The slot options and class options of the <tt>defclass</tt> form provide
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mechanisms for the following:
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<P>
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<UL><LI> Supplying a default initial value form for a given slot.
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<P>
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<LI> Requesting that methods for generic functions
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be automatically generated for reading or writing slots.
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<P>
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<LI> Controlling whether a given slot is shared by instances
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of the class or whether each instance of the class has its own slot.
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<P>
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<LI> Supplying a set of initialization arguments and initialization
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argument defaults to be used in instance creation.
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<P>
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<P>
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<LI> Indicating that the metaclass is to be other than the default.
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<P>
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<LI> Indicating the expected type for the value stored in the slot.
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<P>
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<LI> Indicating the documentation string for the slot.
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<P>
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</UL>
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<br><img align=bottom alt="change_end" src="gif/change_end.gif">
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<P>
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<BR> <HR><A NAME=tex2html4962 HREF="node265.html"><IMG ALIGN=BOTTOM ALT="next" SRC="icons/next_motif.gif"></A> <A NAME=tex2html4960 HREF="node263.html"><IMG ALIGN=BOTTOM ALT="up" SRC="icons/up_motif.gif"></A> <A NAME=tex2html4954 HREF="node263.html"><IMG ALIGN=BOTTOM ALT="previous" SRC="icons/previous_motif.gif"></A> <A NAME=tex2html4964 HREF="node1.html"><IMG ALIGN=BOTTOM ALT="contents" SRC="icons/contents_motif.gif"></A> <A NAME=tex2html4965 HREF="index.html"><IMG ALIGN=BOTTOM ALT="index" SRC="icons/index_motif.gif"></A> <BR>
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<B> Next:</B> <A NAME=tex2html4963 HREF="node265.html"> Creating Instances of </A>
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<B>Up:</B> <A NAME=tex2html4961 HREF="node263.html"> Classes</A>
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<B> Previous:</B> <A NAME=tex2html4955 HREF="node263.html"> Classes</A>
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<HR> <P>
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<HR>
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<P><ADDRESS>
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AI.Repository@cs.cmu.edu
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</ADDRESS>
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