62 lines
4.1 KiB
HTML
62 lines
4.1 KiB
HTML
|
<!DOCTYPE HTML PUBLIC "-//W3O//DTD W3 HTML 2.0//EN">
|
||
|
|
<!Converted with LaTeX2HTML 0.6.5 (Tue Nov 15 1994) by Nikos Drakos (nikos@cbl.leeds.ac.uk), CBLU, University of Leeds >
|
||
|
|
<HEAD>
|
||
|
|
<TITLE>28.1.11.2. Initializing Newly Added Local Slots</TITLE>
|
||
|
|
</HEAD>
|
||
|
|
<BODY>
|
||
|
|
<meta name="description" value=" Initializing Newly Added Local Slots">
|
||
|
|
<meta name="keywords" value="clm">
|
||
|
|
<meta name="resource-type" value="document">
|
||
|
|
<meta name="distribution" value="global">
|
||
|
|
<P>
|
||
|
|
<b>Common Lisp the Language, 2nd Edition</b>
|
||
|
|
<BR> <HR><A NAME=tex2html5494 HREF="node308.html"><IMG ALIGN=BOTTOM ALT="next" SRC="icons/next_motif.gif"></A> <A NAME=tex2html5492 HREF="node305.html"><IMG ALIGN=BOTTOM ALT="up" SRC="icons/up_motif.gif"></A> <A NAME=tex2html5486 HREF="node306.html"><IMG ALIGN=BOTTOM ALT="previous" SRC="icons/previous_motif.gif"></A> <A NAME=tex2html5496 HREF="node1.html"><IMG ALIGN=BOTTOM ALT="contents" SRC="icons/contents_motif.gif"></A> <A NAME=tex2html5497 HREF="index.html"><IMG ALIGN=BOTTOM ALT="index" SRC="icons/index_motif.gif"></A> <BR>
|
||
|
|
<B> Next:</B> <A NAME=tex2html5495 HREF="node308.html"> Customizing the Change </A>
|
||
|
|
<B>Up:</B> <A NAME=tex2html5493 HREF="node305.html"> Changing the Class </A>
|
||
|
|
<B> Previous:</B> <A NAME=tex2html5487 HREF="node306.html"> Modifying the Structure </A>
|
||
|
|
<HR> <P>
|
||
|
|
<H3><A NAME=SECTION0032111200000000000000>28.1.11.2. Initializing Newly Added Local Slots</A></H3>
|
||
|
|
<P>
|
||
|
|
<img align=bottom alt="change_begin" src="gif/change_begin.gif"><br>
|
||
|
|
The second step of the update initializes the newly added slots and
|
||
|
|
performs any other user-defined actions. This step is implemented by
|
||
|
|
the generic function <tt>update-instance-for-different-class</tt>. The
|
||
|
|
generic function <tt>update-instance-for-different-class</tt> is invoked
|
||
|
|
by <tt>change-class</tt> after the first step of the update has been
|
||
|
|
completed.
|
||
|
|
<P>
|
||
|
|
The generic function <tt>update-instance-for-different-class</tt> is
|
||
|
|
invoked on two arguments computed by <tt>change-class</tt>. The first
|
||
|
|
argument passed is a copy of the instance being updated and is an
|
||
|
|
instance of the class <IMG ALIGN=BOTTOM ALT="" SRC="_24769_tex2html_wrap43651.gif">; this copy has
|
||
|
|
dynamic extent within the generic function <tt>change-class</tt>. The
|
||
|
|
second argument is the instance as updated so far by <tt>change-class</tt>
|
||
|
|
and is an instance of the class <IMG ALIGN=BOTTOM ALT="" SRC="_24769_tex2html_wrap43635.gif">.
|
||
|
|
<P>
|
||
|
|
The generic function <tt>update-instance-for-different-class</tt> also
|
||
|
|
takes any number of initialization arguments. When it is called by
|
||
|
|
<tt>change-class</tt>, no initialization arguments are provided.
|
||
|
|
<P>
|
||
|
|
There is a system-supplied primary method for the generic function
|
||
|
|
<tt>update-instance-for-different-class</tt> that has two parameter
|
||
|
|
specializers, each of which is the class <tt>standard-object</tt>. First
|
||
|
|
this method checks the validity of initialization arguments and
|
||
|
|
signals an error if an initialization argument is supplied that is not
|
||
|
|
declared valid (see section <A HREF="node294.html#DeclaringtheValidityofInitializationArgumentsSECTION">28.1.9.2</A>).
|
||
|
|
Then it calls the
|
||
|
|
generic function <tt>shared-initialize</tt> with the following arguments:
|
||
|
|
the instance, a list of names of the newly added slots, and the
|
||
|
|
initialization arguments it received.
|
||
|
|
<br><img align=bottom alt="change_end" src="gif/change_end.gif">
|
||
|
|
<P>
|
||
|
|
<BR> <HR><A NAME=tex2html5494 HREF="node308.html"><IMG ALIGN=BOTTOM ALT="next" SRC="icons/next_motif.gif"></A> <A NAME=tex2html5492 HREF="node305.html"><IMG ALIGN=BOTTOM ALT="up" SRC="icons/up_motif.gif"></A> <A NAME=tex2html5486 HREF="node306.html"><IMG ALIGN=BOTTOM ALT="previous" SRC="icons/previous_motif.gif"></A> <A NAME=tex2html5496 HREF="node1.html"><IMG ALIGN=BOTTOM ALT="contents" SRC="icons/contents_motif.gif"></A> <A NAME=tex2html5497 HREF="index.html"><IMG ALIGN=BOTTOM ALT="index" SRC="icons/index_motif.gif"></A> <BR>
|
||
|
|
<B> Next:</B> <A NAME=tex2html5495 HREF="node308.html"> Customizing the Change </A>
|
||
|
|
<B>Up:</B> <A NAME=tex2html5493 HREF="node305.html"> Changing the Class </A>
|
||
|
|
<B> Previous:</B> <A NAME=tex2html5487 HREF="node306.html"> Modifying the Structure </A>
|
||
|
|
<HR> <P>
|
||
|
|
<HR>
|
||
|
|
<P><ADDRESS>
|
||
|
|
AI.Repository@cs.cmu.edu
|
||
|
|
</ADDRESS>
|
||
|
|
</BODY>
|