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106 lines
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<!DOCTYPE HTML PUBLIC "-//W3O//DTD W3 HTML 2.0//EN">
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<!Converted with LaTeX2HTML 0.6.5 (Tue Nov 15 1994) by Nikos Drakos (nikos@cbl.leeds.ac.uk), CBLU, University of Leeds >
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<TITLE>29. Conditions</TITLE>
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<meta name="description" value=" Conditions">
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<P>
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<b>Common Lisp the Language, 2nd Edition</b>
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<BR> <HR><A NAME=tex2html5547 HREF="node313.html"><IMG ALIGN=BOTTOM ALT="next" SRC="icons/next_motif.gif"></A> <A NAME=tex2html5545 HREF="clm.html"><IMG ALIGN=BOTTOM ALT="up" SRC="icons/up_motif.gif"></A> <A NAME=tex2html5539 HREF="node311.html"><IMG ALIGN=BOTTOM ALT="previous" SRC="icons/previous_motif.gif"></A> <A NAME=tex2html5549 HREF="node1.html"><IMG ALIGN=BOTTOM ALT="contents" SRC="icons/contents_motif.gif"></A> <A NAME=tex2html5550 HREF="index.html"><IMG ALIGN=BOTTOM ALT="index" SRC="icons/index_motif.gif"></A> <BR>
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<B> Next:</B> <A NAME=tex2html5548 HREF="node313.html"> Introduction</A>
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<B>Up:</B> <A NAME=tex2html5546 HREF="clm.html">Common Lisp the Language</A>
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<B> Previous:</B> <A NAME=tex2html5540 HREF="node311.html"> Functions in the </A>
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<HR> <P>
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<H1><A NAME=SECTION003300000000000000000>29. Conditions</A></H1>
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By Kent M. Pitman
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<P>
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<img align=bottom alt="change_begin" src="gif/change_begin.gif"><br>
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<A NAME=CONDITION><TT>PREFACE:</TT></A>
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The language defined by the first edition contained an enormous lacuna:
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although facilities were specified for signaling errors,
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no means was defined for handling errors. This occurred not through neglect
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of the issue, but because this part of the Lisp language generally
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was in a state of flux. There were several proposals at the
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time. The committee, finding that it could not agree on any one proposal,
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agreed to disagree and omit error handling from Common Lisp for the time being.
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This defect has now been addressed.
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<P>
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X3J13 voted in June 1988
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(CONDITION-SYSTEM) <A NAME=36284> </A>
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to adopt the Common Lisp Condition System
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as a part of the forthcoming draft Common Lisp standard.
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X3J13 voted in March 1989 (ZLOS-CONDITIONS) <A NAME=36285> </A>
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to amend the specification of conditions to integrate them
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with the Common Lisp Object System (see chapter <A HREF="node260.html#CLOS">28</A>).
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X3J13 voted in June 1989 (CONDITION-RESTARTS) <A NAME=36287> </A> to amend the
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specification of restarts in certain ways. These amendments have
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been incorporated here with little further comment.
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<P>
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This chapter presents the bulk of the Common Lisp
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Condition System proposal, written by Kent M. Pitman
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and amended by X3J13. I have edited it only very lightly
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to conform to the overall style of this book and have inserted a small
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number of bracketed remarks identified by the initials GLS.
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Please see the Acknowledgments to this second edition for the author's
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acknowledgments to others who contributed to the Condition System proposal.
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<P>
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<blockquote>
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-Guy L. Steele Jr.
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</blockquote>
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<img align=bottom alt="change_end" src="gif/change_end.gif">
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<HR>
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<UL>
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<LI> <A NAME=tex2html5551 HREF="node313.html#SECTION003310000000000000000"> Introduction</A>
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<LI> <A NAME=tex2html5552 HREF="node314.html#SECTION003320000000000000000"> Changes in Terminology</A>
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<LI> <A NAME=tex2html5553 HREF="node315.html#SECTION003330000000000000000"> Survey of Concepts</A>
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<UL>
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<LI> <A NAME=tex2html5554 HREF="node316.html#SECTION003331000000000000000"> Signaling Errors</A>
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<LI> <A NAME=tex2html5555 HREF="node317.html#SECTION003332000000000000000"> Trapping Errors</A>
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<LI> <A NAME=tex2html5556 HREF="node318.html#SECTION003333000000000000000"> Handling Conditions</A>
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<LI> <A NAME=tex2html5557 HREF="node319.html#SECTION003334000000000000000"> Object-Oriented Basis of Condition Handling</A>
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<LI> <A NAME=tex2html5558 HREF="node320.html#SECTION003335000000000000000"> Restarts</A>
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<LI> <A NAME=tex2html5559 HREF="node321.html#SECTION003336000000000000000"> Anonymous Restarts</A>
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<LI> <A NAME=tex2html5560 HREF="node322.html#SECTION003337000000000000000"> Named Restarts</A>
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<LI> <A NAME=tex2html5561 HREF="node323.html#SECTION003338000000000000000"> Restart Functions</A>
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<LI> <A NAME=tex2html5562 HREF="node324.html#SECTION003339000000000000000"> Comparison of Restarts and Catch/Throw</A>
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<LI> <A NAME=tex2html5563 HREF="node325.html#SECTION0033310000000000000000"> Generalized Restarts</A>
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<LI> <A NAME=tex2html5564 HREF="node326.html#SECTION0033311000000000000000"> Interactive Condition Handling</A>
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<LI> <A NAME=tex2html5565 HREF="node327.html#SECTION0033312000000000000000"> Serious Conditions</A>
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<LI> <A NAME=tex2html5566 HREF="node328.html#SECTION0033313000000000000000"> Non-Serious Conditions</A>
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<LI> <A NAME=tex2html5567 HREF="node329.html#SECTION0033314000000000000000"> Condition Types</A>
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<LI> <A NAME=tex2html5568 HREF="node330.html#SECTION0033315000000000000000"> Signaling Conditions</A>
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<LI> <A NAME=tex2html5569 HREF="node331.html#SECTION0033316000000000000000"> Resignaling Conditions</A>
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<LI> <A NAME=tex2html5570 HREF="node332.html#SECTION0033317000000000000000"> Condition Handlers</A>
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<LI> <A NAME=tex2html5571 HREF="node333.html#SECTION0033318000000000000000"> Printing Conditions</A>
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</UL>
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<LI> <A NAME=tex2html5572 HREF="node334.html#SECTION003340000000000000000"> Program Interface to the Condition System</A>
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<UL>
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<LI> <A NAME=tex2html5573 HREF="node335.html#SECTION003341000000000000000"> Signaling Conditions</A>
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<LI> <A NAME=tex2html5574 HREF="node336.html#SECTION003342000000000000000"> Assertions</A>
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<LI> <A NAME=tex2html5575 HREF="node337.html#SECTION003343000000000000000"> Exhaustive Case Analysis</A>
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<LI> <A NAME=tex2html5576 HREF="node338.html#SECTION003344000000000000000"> Handling Conditions</A>
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<LI> <A NAME=tex2html5577 HREF="node339.html#SECTION003345000000000000000"> Defining Conditions</A>
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<LI> <A NAME=tex2html5578 HREF="node340.html#SECTION003346000000000000000"> Creating Conditions</A>
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<LI> <A NAME=tex2html5579 HREF="node341.html#SECTION003347000000000000000"> Establishing Restarts</A>
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<LI> <A NAME=tex2html5580 HREF="node342.html#SECTION003348000000000000000"> Finding and Manipulating Restarts</A>
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<LI> <A NAME=tex2html5581 HREF="node343.html#SECTION003349000000000000000"> Warnings</A>
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<LI> <A NAME=tex2html5582 HREF="node344.html#SECTION0033410000000000000000"> Restart Functions</A>
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<LI> <A NAME=tex2html5583 HREF="node345.html#SECTION0033411000000000000000"> Debugging Utilities</A>
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</UL>
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<LI> <A NAME=tex2html5584 HREF="node346.html#SECTION003350000000000000000"> Predefined Condition Types</A>
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</UL>
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<BR> <HR><A NAME=tex2html5547 HREF="node313.html"><IMG ALIGN=BOTTOM ALT="next" SRC="icons/next_motif.gif"></A> <A NAME=tex2html5545 HREF="clm.html"><IMG ALIGN=BOTTOM ALT="up" SRC="icons/up_motif.gif"></A> <A NAME=tex2html5539 HREF="node311.html"><IMG ALIGN=BOTTOM ALT="previous" SRC="icons/previous_motif.gif"></A> <A NAME=tex2html5549 HREF="node1.html"><IMG ALIGN=BOTTOM ALT="contents" SRC="icons/contents_motif.gif"></A> <A NAME=tex2html5550 HREF="index.html"><IMG ALIGN=BOTTOM ALT="index" SRC="icons/index_motif.gif"></A> <BR>
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<B> Next:</B> <A NAME=tex2html5548 HREF="node313.html"> Introduction</A>
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<B>Up:</B> <A NAME=tex2html5546 HREF="clm.html">Common Lisp the Language</A>
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<B> Previous:</B> <A NAME=tex2html5540 HREF="node311.html"> Functions in the </A>
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<HR> <P>
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<HR>
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<P><ADDRESS>
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AI.Repository@cs.cmu.edu
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