86 lines
7.1 KiB
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86 lines
7.1 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 REMPROP</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="f_get.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Previous]" SRC="../Graphics/Prev.gif" ALIGN=Bottom></A><A REL=UP HREF="c_symbol.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Up]" SRC="../Graphics/Up.gif" ALIGN=Bottom></A><A REL=NEXT HREF="f_boundp.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Next]" SRC="../Graphics/Next.gif" ALIGN=Bottom></A></H1>
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<A NAME="remprop"><I>Function</I> <B>REMPROP</B></A> <P>
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<P><B>Syntax:</B><P>
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<P>
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<B>remprop</B> <I>symbol indicator</I> => <I>generalized-boolean</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>symbol</I>---a <A REL=DEFINITION HREF="26_glo_s.htm#symbol"><I>symbol</I></A>. <P>
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<I>indicator</I>---an <A REL=DEFINITION HREF="26_glo_o.htm#object"><I>object</I></A>. <P>
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<I>generalized-boolean</I>---a <A REL=DEFINITION HREF="26_glo_g.htm#generalized_boolean"><I>generalized boolean</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="#remprop"><B>remprop</B></A> removes from the <A REL=DEFINITION HREF="26_glo_p.htm#property_list"><I>property list</I></A>[2] of <I>symbol</I> a <A REL=DEFINITION HREF="26_glo_p.htm#property"><I>property</I></A>[1] with a <A REL=DEFINITION HREF="26_glo_p.htm#property_indicator"><I>property indicator</I></A> <A REL=DEFINITION HREF="26_glo_i.htm#identical"><I>identical</I></A> to <I>indicator</I>. If there are multiple <A REL=DEFINITION HREF="26_glo_p.htm#property"><I>properties</I></A>[1] with the <A REL=DEFINITION HREF="26_glo_i.htm#identical"><I>identical</I></A> key, <A REL=DEFINITION HREF="#remprop"><B>remprop</B></A> only removes the first such <A REL=DEFINITION HREF="26_glo_p.htm#property"><I>property</I></A>. <A REL=DEFINITION HREF="#remprop"><B>remprop</B></A> returns <A REL=DEFINITION HREF="26_glo_f.htm#false"><I>false</I></A> if no such <A REL=DEFINITION HREF="26_glo_p.htm#property"><I>property</I></A> was found, or <A REL=DEFINITION HREF="26_glo_t.htm#true"><I>true</I></A> if a property was found. <P>
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The <A REL=DEFINITION HREF="26_glo_p.htm#property_indicator"><I>property indicator</I></A> and the corresponding <A REL=DEFINITION HREF="26_glo_p.htm#property_value"><I>property value</I></A> are removed in an undefined order by destructively splicing the property list. The permissible side-effects correspond to those permitted for <A REL=DEFINITION HREF="m_remf.htm#remf"><B>remf</B></A>, such that: <P>
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<PRE>
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(remprop x y) == (remf (symbol-plist x) y)
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</PRE>
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</TT> <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 test (make-symbol "PSEUDO-PI")) => #:PSEUDO-PI
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(symbol-plist test) => ()
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(setf (get test 'constant) t) => T
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(setf (get test 'approximation) 3.14) => 3.14
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(setf (get test 'error-range) 'noticeable) => NOTICEABLE
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(symbol-plist test)
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=> (ERROR-RANGE NOTICEABLE APPROXIMATION 3.14 CONSTANT T)
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(setf (get test 'approximation) nil) => NIL
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(symbol-plist test)
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=> (ERROR-RANGE NOTICEABLE APPROXIMATION NIL CONSTANT T)
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(get test 'approximation) => NIL
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(remprop test 'approximation) => <A REL=DEFINITION HREF="26_glo_t.htm#true">true</A>
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(get test 'approximation) => NIL
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(symbol-plist test)
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=> (ERROR-RANGE NOTICEABLE CONSTANT T)
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(remprop test 'approximation) => NIL
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(symbol-plist test)
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=> (ERROR-RANGE NOTICEABLE CONSTANT T)
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(remprop test 'error-range) => <A REL=DEFINITION HREF="26_glo_t.htm#true">true</A>
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(setf (get test 'approximation) 3) => 3
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(symbol-plist test)
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=> (APPROXIMATION 3 CONSTANT T)
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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#property_list"><I>property list</I></A> of <I>symbol</I> is modified. <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><P>
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<P>
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Should signal an error of <A REL=DEFINITION HREF="26_glo_t.htm#type"><I>type</I></A> <A REL=DEFINITION HREF="e_tp_err.htm#type-error"><B>type-error</B></A> if <I>symbol</I> is not a <A REL=DEFINITION HREF="26_glo_s.htm#symbol"><I>symbol</I></A>. <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_remf.htm#remf"><B>remf</B></A>, <A REL=DEFINITION HREF="f_symb_4.htm#symbol-plist"><B>symbol-plist</B></A> <P>
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<P><B>Notes:</B><P>
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<P>
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<A REL=DEFINITION HREF="26_glo_n.htm#number"><I>Numbers</I></A> and <A REL=DEFINITION HREF="26_glo_c.htm#character"><I>characters</I></A> are not recommended for use as <I>indicators</I> in portable code since <A REL=DEFINITION HREF="#remprop"><B>remprop</B></A> tests with <A REL=DEFINITION HREF="f_eq.htm#eq"><B>eq</B></A> rather than <A REL=DEFINITION HREF="f_eql.htm#eql"><B>eql</B></A>, and consequently the effect of using such <I>indicators</I> is <A REL=DEFINITION HREF="26_glo_i.htm#implementation-dependent"><I>implementation-dependent</I></A>. Of course, if you've gotten as far as needing to remove such a <A REL=DEFINITION HREF="26_glo_p.htm#property"><I>property</I></A>, you don't have much choice---the time to have been thinking about this was when you used <A REL=DEFINITION HREF="m_setf_.htm#setf"><B>setf</B></A> of <A REL=DEFINITION HREF="f_get.htm#get"><B>get</B></A> to establish the <A REL=DEFINITION HREF="26_glo_p.htm#property"><I>property</I></A>. <P>
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<P><HR>The following <A REL=META HREF="../Front/X3J13Iss.htm">X3J13 cleanup issues</A>, <I>not part of the specification</I>, apply to this section:<P><UL><LI> <A REL=CHILD HREF="../Issues/iss293.htm">REMF-DESTRUCTION-UNSPECIFIED:X3J13-MAR-89</A><LI> <A REL=CHILD HREF="../Issues/iss269.htm">PLIST-DUPLICATES:ALLOW</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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