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104 lines
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<H2>Issue DISASSEMBLE-SIDE-EFFECT Writeup</H2>
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<PRE><B>Issue:</B> <A HREF="iss131.htm">DISASSEMBLE-SIDE-EFFECT</A><P>
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<B>References:</B> <A REL=DEFINITION HREF="../Body/f_disass.htm#disassemble"><B>DISASSEMBLE</B></A> (p. 439), <A REL=DEFINITION HREF="../Body/f_cmp.htm#compile"><B>COMPILE</B></A> (p. 439)<P>
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<B>Category:</B> CLARIFICATION<P>
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<B>Edit history:</B> Version 2 by Pierson 12/30/87<P>
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Version 3 by Pierson 1/21/88<P>
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Version 4 by Pierson 6/10/88 correct VAX Lisp practice<P>
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<B>Status:</B> Ready For Release?<P>
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<P>
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<B>Problem description:<P>
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</B><P>
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The definition of <A REL=DEFINITION HREF="../Body/f_disass.htm#disassemble"><B>DISASSEMBLE</B></A> says that "if the relevant function is<P>
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not a compiled function, it is first compiled.". The definition of<P>
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<A REL=DEFINITION HREF="../Body/f_cmp.htm#compile"><B>COMPILE</B></A> says that "If name is a non-nil symbol, then the<P>
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<A REL=DEFINITION HREF="../Body/t_cmpd_f.htm#compiled-function"><B>compiled-function</B></A> is installed as the global function definition of<P>
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the symbol...". Several implementations have taken this to mean that<P>
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if <A REL=DEFINITION HREF="../Body/f_disass.htm#disassemble"><B>DISASSEMBLE</B></A> is passed a symbol which has an uncompiled function<P>
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definition, then it has the side-effect of (<A REL=DEFINITION HREF="../Body/f_cmp.htm#compile"><B>COMPILE</B></A> 'symbol).<P>
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<P>
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<B>Proposal (DISASSEMBLE-SIDE-EFFECT:DO-NOT-INSTALL):<P>
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</B><P>
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Clarify that when <A REL=DEFINITION HREF="../Body/f_disass.htm#disassemble"><B>DISASSEMBLE</B></A> compiles a function, it will never<P>
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install the newly compiled function.<P>
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<P>
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<B>Test Cases/Examples:<P>
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</B><P>
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(<A REL=DEFINITION HREF="../Body/m_defun.htm#defun"><B>DEFUN</B></A> F (A) (<A REL=DEFINITION HREF="../Body/f_1pl_1_.htm#1PL"><B>1+</B></A> A))<P>
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(<A REL=DEFINITION HREF="../Body/f_eq.htm#eq"><B>EQ</B></A> (<A REL=DEFINITION HREF="../Body/f_symb_1.htm#symbol-function"><B>SYMBOL-FUNCTION</B></A> 'F)<P>
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(<A REL=DEFINITION HREF="../Body/s_progn.htm#progn"><B>PROGN</B></A> (<A REL=DEFINITION HREF="../Body/f_disass.htm#disassemble"><B>DISASSEMBLE</B></A> 'F)<P>
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(<A REL=DEFINITION HREF="../Body/f_symb_1.htm#symbol-function"><B>SYMBOL-FUNCTION</B></A> 'F)))<P>
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<P>
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This code will return T if this proposal is adopted. Some current<P>
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implementations will return T, some will return <A REL=DEFINITION HREF="../Body/a_nil.htm#nil"><B>NIL</B></A>.<P>
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<P>
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<B>Rationale:<P>
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</B><P>
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Several current implementations of <A REL=DEFINITION HREF="../Body/f_disass.htm#disassemble"><B>DISASSEMBLE</B></A> have surprising side<P>
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effects, especially for new users.<P>
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<P>
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<B>Current practice:<P>
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</B><P>
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Allegro CL installs the compiled definition. Lucid, Symbolics, Xerox,<P>
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VAX Lisp, and KCL don't install 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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Some implementations will have to make a simple change.<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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Very little. <A REL=DEFINITION HREF="../Body/f_disass.htm#disassemble"><B>DISASSEMBLE</B></A> is really part of the environment and is<P>
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probably not called by much, if any user code.<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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<A REL=DEFINITION HREF="../Body/f_disass.htm#disassemble"><B>DISASSEMBLE</B></A> will continue to surprise less experienced users.<P>
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<P>
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<B>Benefits:<P>
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</B><P>
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<A REL=DEFINITION HREF="../Body/f_disass.htm#disassemble"><B>DISASSEMBLE</B></A> will become the predictable debugging function it was<P>
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meant to be.<P>
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<P>
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<B>Aesthetics:<P>
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</B><P>
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Some who worried that <A REL=DEFINITION HREF="../Body/f_disass.htm#disassemble"><B>DISASSEMBLE</B></A> was supposed to install the compiled<P>
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function may find that the language has become a little cleaner.<P>
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<P>
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<B>Discussion:<P>
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</B><P>
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<A REL=DEFINITION HREF="../Body/f_disass.htm#disassemble"><B>DISASSEMBLE</B></A> is an environment feature; some question has been raised<P>
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as to the place and force of environment features in the <A REL=DEFINITION HREF="../Body/07_ffb.htm#standard"><B>standard</B></A>.<P>
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However, this proposal stands if <A REL=DEFINITION HREF="../Body/f_disass.htm#disassemble"><B>DISASSEMBLE</B></A> is part of the <A REL=DEFINITION HREF="../Body/07_ffb.htm#standard"><B>standard</B></A><P>
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language.<P>
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<P>
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</PRE>
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