78 lines
5.4 KiB
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78 lines
5.4 KiB
HTML
<!-- Common Lisp HyperSpec (TM), version 7.0 generated by Kent M. Pitman on Mon, 11-Apr-2005 2:31am EDT -->
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<TITLE>CLHS: Function COPY-READTABLE</TITLE>
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<A NAME="copy-readtable"><I>Function</I> <B>COPY-READTABLE</B></A> <P>
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<P><B>Syntax:</B><P>
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<P>
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<B>copy-readtable</B> <I><TT>&optional</TT> from-readtable to-readtable</I> => <I>readtable</I><P>
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<P>
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<P><B>Arguments and Values:</B><P>
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<P>
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<I>from-readtable</I>---a <A REL=DEFINITION HREF="26_glo_r.htm#readtable_designator"><I>readtable designator</I></A>. The default is the <A REL=DEFINITION HREF="26_glo_c.htm#current_readtable"><I>current readtable</I></A>. <P>
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<I>to-readtable</I>---a <A REL=DEFINITION HREF="26_glo_r.htm#readtable"><I>readtable</I></A> or <A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A>. The default is <A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A>. <P>
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<I>readtable</I>---the <I>to-readtable</I> if it is <A REL=DEFINITION HREF="26_glo_n.htm#non-nil"><I>non-nil</I></A>, or else a <A REL=DEFINITION HREF="26_glo_f.htm#fresh"><I>fresh</I></A> <A REL=DEFINITION HREF="26_glo_r.htm#readtable"><I>readtable</I></A>. <P>
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<P><B>Description:</B><P>
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<P>
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<A REL=DEFINITION HREF="#copy-readtable"><B>copy-readtable</B></A> copies <I>from-readtable</I>. <P>
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If <I>to-readtable</I> is <A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A>, a new <A REL=DEFINITION HREF="26_glo_r.htm#readtable"><I>readtable</I></A> is created and returned. Otherwise the <A REL=DEFINITION HREF="26_glo_r.htm#readtable"><I>readtable</I></A> specified by <I>to-readtable</I> is modified and returned. <P>
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<A REL=DEFINITION HREF="#copy-readtable"><B>copy-readtable</B></A> copies the setting of <A REL=DEFINITION HREF="f_rdtabl.htm#readtable-case"><B>readtable-case</B></A>. <P>
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<P><B>Examples:</B><P>
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<P>
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<PRE>
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(setq zvar 123) => 123
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(set-syntax-from-char #\z #\' (setq table2 (copy-readtable))) => T
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zvar => 123
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(copy-readtable table2 *readtable*) => #<READTABLE 614000277>
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zvar => VAR
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(setq *readtable* (copy-readtable)) => #<READTABLE 46210223>
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zvar => VAR
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(setq *readtable* (copy-readtable nil)) => #<READTABLE 46302670>
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zvar => 123
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</PRE>
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</TT> <P>
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<P><B>Affected By:</B> None.
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<P>
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<P><B>Exceptional Situations:</B> None.
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<P>
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<P><B>See Also:</B><P>
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<P>
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<A REL=DEFINITION HREF="t_rdtabl.htm#readtable"><B>readtable</B></A>, <A REL=DEFINITION HREF="v_rdtabl.htm#STreadtableST"><B>*readtable*</B></A> <P>
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<P><B>Notes:</B><P>
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<P>
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<PRE>
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(setq *readtable* (copy-readtable nil))
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</PRE>
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</TT> restores the input syntax to standard Common Lisp syntax, even if the <A REL=DEFINITION HREF="26_glo_i.htm#initial_readtable"><I>initial readtable</I></A> has been clobbered (assuming it is not so badly clobbered that you cannot type in the above expression). <P>
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On the other hand, <P>
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<PRE>
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(setq *readtable* (copy-readtable))
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</PRE>
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</TT> replaces the current <A REL=DEFINITION HREF="26_glo_r.htm#readtable"><I>readtable</I></A> with a copy of itself. This is useful if you want to save a copy of a readtable for later use, protected from alteration in the meantime. It is also useful if you want to locally bind the readtable to a copy of itself, as in: <P>
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<PRE>
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(let ((*readtable* (copy-readtable))) ...)
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</PRE>
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</TT> <P>
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<P><HR>The following <A REL=META HREF="../Front/X3J13Iss.htm">X3J13 cleanup issue</A>, <I>not part of the specification</I>, applies to this section:<P><UL><LI> <A REL=CHILD HREF="../Issues/iss286.htm">READ-CASE-SENSITIVITY:READTABLE-KEYWORDS</A><P></UL><HR>
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