WITHOUT-INTERRUPTS: my last message

[Guy Steele <gls@THINK-AQUINAS.ARPA>]

    Date: Wed, 23 Oct 85 16:04:59 EDT
    From: greek@DEC-HUDSON

    I too promise that this is my last message.

Me, too.

    Mr. Moon is right -- VMS certainly couldn't promise to lock out
    other processes that might touch a shared section.

Sure it could... if it wanted to.  Alternatively, the LISP could
simply refuse to share.

On the third hand, suppose I want to swap the names of two files,
so I do

    (critical-section
	(rename-file "foo" "temp")
	(rename-file "bar" "foo")
	(rename-file "temp" "bar"))

Assuming that files foo and bar both existed to begin with, am I guaranteed
that at no time can any other process get the value NIL for

	(and (probe-file "foo") (probe-file "bar"))

?  That would be an awfully nice property to have.

--Guy