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105 lines
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<TITLE>CLHS: Issue GENTEMP-BAD-IDEA Writeup</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="../Issues/iss182_w.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Previous]" SRC="../Graphics/Prev.gif" ALIGN=Bottom></A><A REL=UP HREF="../Issues/iss183.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Up]" SRC="../Graphics/Up.gif" ALIGN=Bottom></A><A REL=NEXT HREF="../Issues/iss184_w.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Next]" SRC="../Graphics/Next.gif" ALIGN=Bottom></A></H1>
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<H2>Issue GENTEMP-BAD-IDEA Writeup</H2>
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<PRE><B>Issue:</B> <A HREF="iss183.htm">GENTEMP-BAD-IDEA</A><P>
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<B>Forum:</B> X3J13 Letter Ballot<P>
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<B>References:</B> <A REL=DEFINITION HREF="../Body/f_gentem.htm#gentemp"><B>GENTEMP</B></A> (X3J13/92-102 pp10-10..11)<P>
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<B>Category:</B> CHANGE<P>
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<B>Edit history:</B> 04-Jun-93, Version 1 by Pitman<P>
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<B>Status:</B> Proposal DEPRECATE passed 9-2 on letter ballot 93-302.<P>
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<P>
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<B>Problem Description:<P>
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</B><P>
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<A REL=DEFINITION HREF="../Body/f_gentem.htm#gentemp"><B>GENTEMP</B></A> is an `attractive nuisance.' Pitman and many others believe that<P>
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<A REL=DEFINITION HREF="../Body/f_gentem.htm#gentemp"><B>GENTEMP</B></A> should NEVER be used.<P>
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<P>
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Its effects are hard to depend on because they differ from session to<P>
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session.<P>
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<P>
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Its description gives the impression that the symbol it creates is<P>
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unique, but it is easy to establish innocent-looking patterns of data<P>
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flow (when multiple sessions are involved) where the same supposedly<P>
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unique symbol is created for conflicting uses.<P>
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<P>
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<B>Proposal (GENTEMP-BAD-IDEA:DEPRECATE):<P>
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</B><P>
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Deprecate the function <A REL=DEFINITION HREF="../Body/f_gentem.htm#gentemp"><B>GENTEMP</B></A>.<P>
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<P>
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<B>Proposal (GENTEMP-BAD-IDEA:REMOVE):<P>
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</B><P>
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Remove the function <A REL=DEFINITION HREF="../Body/f_gentem.htm#gentemp"><B>GENTEMP</B></A> from the language.<P>
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<P>
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<B>Test Case:<P>
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</B><P>
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None.<P>
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<P>
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<B>Rationale:<P>
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</B><P>
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The potential bad effects of <A REL=DEFINITION HREF="../Body/f_gentem.htm#gentemp"><B>GENTEMP</B></A> are large, and there is no real<P>
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benfit. Anyone who really needs this could write it trivially given<P>
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the primitives already in the language.<P>
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<P>
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<B>Current Practice:<P>
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</B><P>
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Presumably all implementations <A REL=DEFINITION HREF="../Body/f_provid.htm#provide"><B>provide</B></A> it.<P>
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<P>
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<B>Cost to Implementors:<P>
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</B><P>
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Very small.<P>
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<P>
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<B>Cost to Users:<P>
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</B><P>
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Small. (In the worst case, users will have to write a one-liner<P>
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to patch over it if they really need it.)<P>
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<P>
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<B>Cost of Non-Adoption:<P>
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</B><P>
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Users might think this function was more useful than it was, and might<P>
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fall into some of its traps.<P>
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<P>
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<B>Benefits:<P>
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</B><P>
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Language is one page shorter.<P>
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<P>
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<B>Editorial Impact:<P>
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</B><P>
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A small, well-isolated change, plus a quick sweep of the sources<P>
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to make sure there are no stray references.<P>
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<P>
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<B>Aesthetics:<P>
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</B><P>
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<A REL=DEFINITION HREF="../Body/f_gentem.htm#gentemp"><B>GENTEMP</B></A> is not aesthetic.<P>
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<P>
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<B>Discussion:<P>
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</B><P>
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This is in response to Pitman's comment #19, first Public Review.<P>
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Pitman supports the proposal.<P>
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<P>
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</PRE>
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