bug#27016: possible bug in `defsetf'

[Rafael D Sorkin <rsorkin@perimeterinstitute.ca>]

 > `defun' takes effect at runtime (or rather it expands to
 > `defalias' which operates at runtime), whereas `defsetf' has
 > to affect subsequent compilation, so waiting until runtime to
 > decide whether the condition is true could not really work.

Well the way I was using it, everything used to work fine.  I
found the bug when it stopped working and I was unable to figure
out why.

I had a defsetf inside a conditional in a file that was to be
loaded and/or compiled and then loaded.  (Compilation isn't
really the issue.)  Before loading that file I set a "switch"
which the conditional referred to.  That way a defsetf done
before loading the file could be either overridden or not, as
desired.

I found the ability to control the defsetf this way to be
useful.  However, as I wrote before, I only used this device a
few times, not so many that I couldn't adapt to losing it.

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 Rafael Sorkin
 Perimeter Institute for Theoretical Physics
 31 Caroline Street North
 Waterloo, ON  N2L 2Y5
 Canada
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