75 lines
6.2 KiB
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75 lines
6.2 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 FIND-RESTART</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_comp_1.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Previous]" SRC="../Graphics/Prev.gif" ALIGN=Bottom></A><A REL=UP HREF="c_condit.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Up]" SRC="../Graphics/Up.gif" ALIGN=Bottom></A><A REL=NEXT HREF="f_invo_1.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Next]" SRC="../Graphics/Next.gif" ALIGN=Bottom></A></H1>
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<A NAME="find-restart"><I>Function</I> <B>FIND-RESTART</B></A> <P>
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<P><B>Syntax:</B><P>
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<P>
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<B>find-restart</B> <I>identifier <TT>&optional</TT> condition</I><P>
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restart <P>
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<P><B>Arguments and Values:</B><P>
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<P>
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<I>identifier</I>---a <A REL=DEFINITION HREF="26_glo_n.htm#non-nil"><I>non-nil</I></A> <A REL=DEFINITION HREF="26_glo_s.htm#symbol"><I>symbol</I></A>, or a <A REL=DEFINITION HREF="26_glo_r.htm#restart"><I>restart</I></A>. <P>
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<I>condition</I>---a <A REL=DEFINITION HREF="26_glo_c.htm#condition"><I>condition</I></A> <A REL=DEFINITION HREF="26_glo_o.htm#object"><I>object</I></A>, or <A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A>. <P>
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<I>restart</I>---a <A REL=DEFINITION HREF="26_glo_r.htm#restart"><I>restart</I></A> or <A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A>. <P>
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<P><B>Description:</B><P>
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<P>
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<A REL=DEFINITION HREF="#find-restart"><B>find-restart</B></A> searches for a particular <A REL=DEFINITION HREF="26_glo_r.htm#restart"><I>restart</I></A> in the current <A REL=DEFINITION HREF="26_glo_d.htm#dynamic_environment"><I>dynamic environment</I></A>. <P>
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When <I>condition</I> is <A REL=DEFINITION HREF="26_glo_n.htm#non-nil"><I>non-nil</I></A>, only those <A REL=DEFINITION HREF="26_glo_r.htm#restart"><I>restarts</I></A> are considered that are either explicitly associated with that <I>condition</I>, or not associated with any <A REL=DEFINITION HREF="26_glo_c.htm#condition"><I>condition</I></A>; that is, the excluded <A REL=DEFINITION HREF="26_glo_r.htm#restart"><I>restarts</I></A> are those that are associated with a non-empty set of <A REL=DEFINITION HREF="26_glo_c.htm#condition"><I>conditions</I></A> of which the given <I>condition</I> is not an <A REL=DEFINITION HREF="26_glo_e.htm#element"><I>element</I></A>. If <I>condition</I> is <A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A>, all <A REL=DEFINITION HREF="26_glo_r.htm#restart"><I>restarts</I></A> are considered. <P>
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If <I>identifier</I> is a <A REL=DEFINITION HREF="26_glo_s.htm#symbol"><I>symbol</I></A>, then the innermost (most recently established) <A REL=DEFINITION HREF="26_glo_a.htm#applicable_restart"><I>applicable restart</I></A> with that <A REL=DEFINITION HREF="26_glo_n.htm#name"><I>name</I></A> is returned. <A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A> is returned if no such restart is found. <P>
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If <I>identifier</I> is a currently active restart, then it is returned. Otherwise, <A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A> is returned. <P>
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<P><B>Examples:</B><P>
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<P>
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<PRE>
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(restart-case
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(let ((r (find-restart 'my-restart)))
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(format t "~S is named ~S" r (restart-name r)))
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(my-restart () nil))
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>> #<RESTART 32307325> is named MY-RESTART
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=> NIL
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(find-restart 'my-restart)
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=> NIL
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</PRE>
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</TT> <P>
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<P><B>Side Effects:</B> None.
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<P>
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<P><B>Affected By:</B><P>
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<P>
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Existing restarts. <P>
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<A REL=DEFINITION HREF="m_rst_ca.htm#restart-case"><B>restart-case</B></A>, <A REL=DEFINITION HREF="m_rst_bi.htm#restart-bind"><B>restart-bind</B></A>, <A REL=DEFINITION HREF="m_w_cnd_.htm#with-condition-restarts"><B>with-condition-restarts</B></A>. <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="f_comp_1.htm#compute-restarts"><B>compute-restarts</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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(find-restart identifier)
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== (find identifier (compute-restarts) :key :restart-name)
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</PRE>
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</TT> <P>
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Although anonymous restarts have a name of <A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A>, the consequences are unspecified if <A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A> is given as an <I>identifier</I>. Occasionally, programmers lament that <A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A> is not permissible as an <I>identifier</I> argument. In most such cases, <A REL=DEFINITION HREF="f_comp_1.htm#compute-restarts"><B>compute-restarts</B></A> can probably be used to simulate the desired effect. <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/iss076.htm">CONDITION-RESTARTS:PERMIT-ASSOCIATION</A><P></UL><HR>
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