69 lines
4.1 KiB
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69 lines
4.1 KiB
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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>2.2.4. Character Attributes</TITLE>
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<BODY>
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<meta name="description" value=" Character Attributes">
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<meta name="keywords" value="clm">
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<meta name="resource-type" value="document">
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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=tex2html1820 HREF="node26.html"><IMG ALIGN=BOTTOM ALT="next" SRC="icons/next_motif.gif"></A> <A NAME=tex2html1818 HREF="node21.html"><IMG ALIGN=BOTTOM ALT="up" SRC="icons/up_motif.gif"></A> <A NAME=tex2html1812 HREF="node24.html"><IMG ALIGN=BOTTOM ALT="previous" SRC="icons/previous_motif.gif"></A> <A NAME=tex2html1822 HREF="node1.html"><IMG ALIGN=BOTTOM ALT="contents" SRC="icons/contents_motif.gif"></A> <A NAME=tex2html1823 HREF="index.html"><IMG ALIGN=BOTTOM ALT="index" SRC="icons/index_motif.gif"></A> <BR>
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<B> Next:</B> <A NAME=tex2html1821 HREF="node26.html"> String Characters</A>
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<B>Up:</B> <A NAME=tex2html1819 HREF="node21.html"> Characters</A>
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<B> Previous:</B> <A NAME=tex2html1813 HREF="node24.html"> Non-standard Characters</A>
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<HR> <P>
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<img align=bottom alt="old_change_begin" src="gif/old_change_begin.gif"><br>
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<H2><A NAME=SECTION00624000000000000000>2.2.4. Character Attributes</A></H2>
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<P>
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Every object of type <tt>character</tt>
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has three attributes: <i>code</i>, <i>bits</i>, and <i>font</i>.
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The code attribute is intended to distinguish among the printed glyphs
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and formatting functions for characters; it is a numerical encoding
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of the character proper.
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The bits attribute allows extra
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flags to be associated with a character. The font attribute permits
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a specification of the style of the glyphs (such as italics).
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Each of these attributes may be understood to be a non-negative integer.
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<P>
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The font attribute may be notated in unsigned decimal notation
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between the <tt>#</tt> and the <tt>\</tt>. For example,
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<tt>#3\a</tt> means the letter <tt>a</tt> in font 3.
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This might mean the same thing as <tt>#\<IMG ALIGN=BOTTOM ALT="" SRC="_24769_tex2html_wrap40236.gif"></tt> if font 3
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were used to represent Greek letters.
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Note that not all Common Lisp implementations provide for non-zero
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font attributes; see <tt>char-font-limit</tt>.
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<P>
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The bits attribute may be notated
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by preceding the name of the character by the names or initials
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of the bits,
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separated by hyphens. The character itself may be written
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instead of the name, preceded if necessary by <tt>\</tt>. For example:
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<P><pre>
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#\Control-Meta-Return #\Meta-Control-Q
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#\Hyper-Space #\Meta-\a
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#\Control-A #\Meta-Hyper-\:
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#\C-M-Return #\Hyper-\<IMG ALIGN=BOTTOM ALT="" SRC="_24769_tex2html_wrap40211.gif">
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</pre><P>
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Note that not all Common Lisp implementations provide for non-zero
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bits attributes; see <tt>char-bits-limit</tt>.
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<br><img align=bottom alt="old_change_end" src="gif/old_change_end.gif">
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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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X3J13 voted in March 1989 (CHARACTER-PROPOSAL) <A NAME=1016> </A>
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to replace the notion of bits and font attributes with
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that of implementation-defined attributes.
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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=tex2html1820 HREF="node26.html"><IMG ALIGN=BOTTOM ALT="next" SRC="icons/next_motif.gif"></A> <A NAME=tex2html1818 HREF="node21.html"><IMG ALIGN=BOTTOM ALT="up" SRC="icons/up_motif.gif"></A> <A NAME=tex2html1812 HREF="node24.html"><IMG ALIGN=BOTTOM ALT="previous" SRC="icons/previous_motif.gif"></A> <A NAME=tex2html1822 HREF="node1.html"><IMG ALIGN=BOTTOM ALT="contents" SRC="icons/contents_motif.gif"></A> <A NAME=tex2html1823 HREF="index.html"><IMG ALIGN=BOTTOM ALT="index" SRC="icons/index_motif.gif"></A> <BR>
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<B> Next:</B> <A NAME=tex2html1821 HREF="node26.html"> String Characters</A>
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<B>Up:</B> <A NAME=tex2html1819 HREF="node21.html"> Characters</A>
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<B> Previous:</B> <A NAME=tex2html1813 HREF="node24.html"> Non-standard Characters</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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