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32 lines
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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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<TITLE>CLHS: Section 4.3.6.2</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="04_cfa.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Previous]" SRC="../Graphics/Prev.gif" ALIGN=Bottom></A><A REL=UP HREF="04_cf.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Up]" SRC="../Graphics/Up.gif" ALIGN=Bottom></A><A REL=NEXT HREF="04_cfc.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Next]" SRC="../Graphics/Next.gif" ALIGN=Bottom></A></H1>
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<H2>
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4.3.6.2 Initializing Newly Added Local Slots</H2> <P>
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The second step initializes the newly added <A REL=DEFINITION HREF="26_glo_l.htm#local_slot"><I>local slots</I></A> and performs any other user-defined actions. This step is implemented by the generic function <A REL=DEFINITION HREF="f_upda_1.htm#update-instance-for-redefined-class"><B>update-instance-for-redefined-class</B></A>, which is called after completion of the first step of modifying the structure of the <A REL=DEFINITION HREF="26_glo_i.htm#instance"><I>instance</I></A>. <P>
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The generic function <A REL=DEFINITION HREF="f_upda_1.htm#update-instance-for-redefined-class"><B>update-instance-for-redefined-class</B></A> takes four required arguments: the <A REL=DEFINITION HREF="26_glo_i.htm#instance"><I>instance</I></A> being updated after it has undergone the first step, a list of the names of <A REL=DEFINITION HREF="26_glo_l.htm#local_slot"><I>local slots</I></A> that were added, a list of the names of <A REL=DEFINITION HREF="26_glo_l.htm#local_slot"><I>local slots</I></A> that were discarded, and a property list containing the <A REL=DEFINITION HREF="26_glo_s.htm#slot"><I>slot</I></A> names and values of <A REL=DEFINITION HREF="26_glo_s.htm#slot"><I>slots</I></A> that were discarded and had values. Included among the discarded <A REL=DEFINITION HREF="26_glo_s.htm#slot"><I>slots</I></A> are <A REL=DEFINITION HREF="26_glo_s.htm#slot"><I>slots</I></A> that were local in the old <A REL=DEFINITION HREF="26_glo_c.htm#class"><I>class</I></A> and that are shared in the new <A REL=DEFINITION HREF="26_glo_c.htm#class"><I>class</I></A>. <P>
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The generic function <A REL=DEFINITION HREF="f_upda_1.htm#update-instance-for-redefined-class"><B>update-instance-for-redefined-class</B></A> also takes any number of initialization arguments. When it is called by the system to update an <A REL=DEFINITION HREF="26_glo_i.htm#instance"><I>instance</I></A> whose <A REL=DEFINITION HREF="26_glo_c.htm#class"><I>class</I></A> has been redefined, no initialization arguments are provided. <P>
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There is a system-supplied primary <A REL=DEFINITION HREF="26_glo_m.htm#method"><I>method</I></A> for <A REL=DEFINITION HREF="f_upda_1.htm#update-instance-for-redefined-class"><B>update-instance-for-redefined-class</B></A> whose <A REL=DEFINITION HREF="26_glo_p.htm#parameter_specializer"><I>parameter specializer</I></A> for its <A REL=DEFINITION HREF="26_glo_i.htm#instance"><I>instance</I></A> argument is the <A REL=DEFINITION HREF="26_glo_c.htm#class"><I>class</I></A> <A REL=DEFINITION HREF="t_std_ob.htm#standard-object"><B>standard-object</B></A>. First this <A REL=DEFINITION HREF="26_glo_m.htm#method"><I>method</I></A> checks the validity of initialization arguments and signals an error if an initialization argument is supplied that is not declared as valid. (For more information, see <A REL=CHILD HREF="07_ab.htm">Section 7.1.2 (Declaring the Validity of Initialization Arguments)</A>.) Then it calls the generic function <A REL=DEFINITION HREF="f_shared.htm#shared-initialize"><B>shared-initialize</B></A> with the following arguments: the <A REL=DEFINITION HREF="26_glo_i.htm#instance"><I>instance</I></A>, the list of <A REL=DEFINITION HREF="26_glo_n.htm#name"><I>names</I></A> of the newly added <A REL=DEFINITION HREF="26_glo_s.htm#slot"><I>slots</I></A>, and the initialization arguments it received. <P>
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