85 lines
5.1 KiB
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85 lines
5.1 KiB
HTML
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<!-- Common Lisp HyperSpec (TM), version 7.0 generated by Kent M. Pitman on Mon, 11-Apr-2005 2:31am EDT -->
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<HTML>
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<HEAD>
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<TITLE>CLHS: Special Form SETQ</TITLE>
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<H1><A REV=MADE HREF="http://www.lispworks.com/"><IMG WIDTH=80 HEIGHT=65 ALT="[LISPWORKS]" SRC="../Graphics/LWSmall.gif" ALIGN=Bottom></A><A REL=TOP HREF="../Front/index.htm"><IMG WIDTH=237 HEIGHT=65 ALT="[Common Lisp HyperSpec (TM)]" SRC="../Graphics/CLHS_Sm.gif" ALIGN=Bottom></A> <A REL=PREV HREF="s_progv.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Previous]" SRC="../Graphics/Prev.gif" ALIGN=Bottom></A><A REL=UP HREF="c_data_a.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Up]" SRC="../Graphics/Up.gif" ALIGN=Bottom></A><A REL=NEXT HREF="m_psetq.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Next]" SRC="../Graphics/Next.gif" ALIGN=Bottom></A></H1>
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<HR>
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<A NAME="setq"><I>Special Form</I> <B>SETQ</B></A> <P>
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<P><B>Syntax:</B><P>
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<P>
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<B>setq</B> <I>{<I>pair</I>}<B>*</B></I> => <I>result</I><P>
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<P>
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<PRE>
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pair::= var form
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</PRE>
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<P>
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<P><B>Pronunciation:</B><P>
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<P>
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['set,kyoo] <P>
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<P><B>Arguments and Values:</B><P>
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<P>
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<I>var</I>---a <A REL=DEFINITION HREF="26_glo_s.htm#symbol"><I>symbol</I></A> naming a <A REL=DEFINITION HREF="26_glo_v.htm#variable"><I>variable</I></A> other than a <A REL=DEFINITION HREF="26_glo_c.htm#constant_variable"><I>constant variable</I></A>. <P>
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<I>form</I>---a <A REL=DEFINITION HREF="26_glo_f.htm#form"><I>form</I></A>. <P>
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<I>result</I>---the <A REL=DEFINITION HREF="26_glo_p.htm#primary_value"><I>primary value</I></A> of the last <I>form</I>, or <A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A> if no <I>pairs</I> were supplied. <P>
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<P><B>Description:</B><P>
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<P>
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Assigns values to <A REL=DEFINITION HREF="26_glo_v.htm#variable"><I>variables</I></A>. <P>
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<TT>(setq </TT><I>var1</I><TT> </TT><I>form1</I><TT> </TT><I>var2</I><TT> </TT><I>form2</I><TT> ...)</TT> is the simple variable assignment statement of Lisp. First <I>form1</I> is evaluated and the result is stored in the variable <I>var1</I>, then <I>form2</I> is evaluated and the result stored in <I>var2</I>, and so forth. <A REL=DEFINITION HREF="#setq"><B>setq</B></A> may be used for assignment of both lexical and dynamic variables. <P>
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If any <I>var</I> refers to a <A REL=DEFINITION HREF="26_glo_b.htm#binding"><I>binding</I></A> made by <A REL=DEFINITION HREF="s_symbol.htm#symbol-macrolet"><B>symbol-macrolet</B></A>, then that <I>var</I> is treated as if <A REL=DEFINITION HREF="m_setf_.htm#setf"><B>setf</B></A> (not <A REL=DEFINITION HREF="#setq"><B>setq</B></A>) had been used. <P>
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<P><B>Examples:</B><P>
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<P>
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<PRE>
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;; A simple use of SETQ to establish values for variables.
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(setq a 1 b 2 c 3) => 3
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a => 1
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b => 2
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c => 3
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;; Use of SETQ to update values by sequential assignment.
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(setq a (1+ b) b (1+ a) c (+ a b)) => 7
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a => 3
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b => 4
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c => 7
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;; This illustrates the use of SETQ on a symbol macro.
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(let ((x (list 10 20 30)))
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(symbol-macrolet ((y (car x)) (z (cadr x)))
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(setq y (1+ z) z (1+ y))
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(list x y z)))
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=> ((21 22 30) 21 22)
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</PRE>
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</TT> <P>
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<P><B>Side Effects:</B><P>
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<P>
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The <A REL=DEFINITION HREF="26_glo_p.htm#primary_value"><I>primary value</I></A> of each <I>form</I> is assigned to the corresponding <I>var</I>. <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="m_psetq.htm#psetq"><B>psetq</B></A>, <A REL=DEFINITION HREF="f_set.htm#set"><B>set</B></A>, <A REL=DEFINITION HREF="m_setf_.htm#setf"><B>setf</B></A> <P>
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<P><B>Notes:</B> None.
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<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/iss338.htm">SYMBOL-MACROLET-SEMANTICS:SPECIAL-FORM</A><P></UL><HR>
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<A REL=NAVIGATOR HREF="../Front/StartPts.htm"><IMG WIDTH=80 HEIGHT=40 ALT="[Starting Points]" SRC="../Graphics/StartPts.gif" ALIGN=Bottom></A><A REL=TOC HREF="../Front/Contents.htm"><IMG WIDTH=80 HEIGHT=40 ALT="[Contents]" SRC="../Graphics/Contents.gif" ALIGN=Bottom></A><A REL=INDEX HREF="../Front/X_Master.htm"><IMG WIDTH=80 HEIGHT=40 ALT="[Index]" SRC="../Graphics/Index.gif" ALIGN=Bottom></A><A REL=INDEX HREF="../Front/X_Symbol.htm"><IMG WIDTH=80 HEIGHT=40 ALT="[Symbols]" SRC="../Graphics/Symbols.gif" ALIGN=Bottom></A><A REL=GLOSSARY HREF="../Body/26_a.htm"><IMG WIDTH=80 HEIGHT=40 ALT="[Glossary]" SRC="../Graphics/Glossary.gif" ALIGN=Bottom></A><A HREF="../Front/X3J13Iss.htm"><IMG WIDTH=80 HEIGHT=40 ALT="[Issues]" SRC="../Graphics/Issues.gif" ALIGN=Bottom></A><BR>
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<A REL=COPYRIGHT HREF="../Front/Help.htm#Legal"><I>Copyright 1996-2005, LispWorks Ltd. All rights reserved.</I></A><P>
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