Issue: DISASSEMBLE-SIDE-EFFECT (version 4)

[Dan L. Pierson <pierson%mist@multimax.ARPA>]

Walter asked for this correction and I can't remember whether this was
formally passed last meeting or not.  If it was, then I'd prefer not
to disturb it.

Issue:         DISASSEMBLE-SIDE-EFFECT
References:    DISASSEMBLE (p. 439), COMPILE (p. 439)
Category:      CLARIFICATION
Edit history:  Version 2 by Pierson 12/30/87
               Version 3 by Pierson  1/21/88
	       Version 4 by Pierson  6/10/88 correct VAX Lisp practice
Status:        Ready For Release?

Problem description:

The definition of DISASSEMBLE says that "if the relevant function is
not a compiled function, it is first compiled.".  The definition of
COMPILE says that "If name is a non-nil symbol, then the
compiled-function is installed as the global function definition of
the symbol...".  Several implementations have taken this to mean that
if DISASSEMBLE is passed a symbol which has an uncompiled function
definition, then it has the side-effect of (COMPILE 'symbol).

Proposal (DISASSEMBLE-SIDE-EFFECT:DO-NOT-INSTALL):

Clarify that when DISASSEMBLE compiles a function, it will never
install the newly compiled function.

Test Cases/Examples:

    (DEFUN F (A) (1+ A))
    (EQ (SYMBOL-FUNCTION 'F)
	(PROGN (DISASSEMBLE 'F)
	       (SYMBOL-FUNCTION 'F)))

This code will return T if this proposal is adopted.  Some current
implementations will return T, some will return NIL.

Rationale:

Several current implementations of DISASSEMBLE have surprising side
effects, especially for new users.

Current practice:

Allegro CL installs the compiled definition.  Lucid, Symbolics, Xerox,
VAX Lisp, and KCL don't install it.

Cost to Implementors:

Some implementations will have to make a simple change.

Cost to Users:

Very little.  DISASSEMBLE is really part of the environment and is
probably not called by much, if any user code.

Cost of non-Adoption:

DISASSEMBLE will continue to surprise less experienced users.

Benefits:

DISASSEMBLE will become the predictable debugging function it was
meant to be.

Aesthetics:

Some who worried that DISASSEMBLE was supposed to install the compiled
function may find that the language has become a little cleaner.

Discussion:

DISASSEMBLE is an environment feature; some question has been raised
as to the place and force of environment features in the standard.
However, this proposal stands if DISASSEMBLE is part of the standard
language.