Re: Presentation type definition question

["Robert W. Kerns" <RWK@f.ila.dialnet.symbolics.com>]

    Date: Mon, 17 Oct 88 17:04 EDT
    From: miller@CS.ROCHESTER.EDU (Brad Miller)
    no, I'm running 7.2...

    Try this instead:

    (defun mumble-p (x) (and (symbolp x) nil))
    (break)
    <<to the debugger, type abort, so you are back at top level.>>

    (accept '((and sys:form ((satisfies mumble-p))) :description "no form"))

    <<to the debugger, type abort, so you are back at top level.>>
This does not put me into the debugger.  Was this a typo?

    <arguments to EVAL in the above debugger trace are sensitive.
    Note that (present 'foo 'sys:expression) and (present 'foo 'sys:form) are
    NOT sensitive, even though the presentation inspector proclaims that the
    presentations of the arguments to EVAL from the (break) are "sys:expression"s.
    I don't claim to understand this, but clearly some sort of bug is involved.>

No bug is involved, or at least not where you think one is.  Look at
your mouse documentation line.  It does not say anything is available to
Mouse Left.  It does say there are operations available on Mouse Right,
however.  If you do Mouse Right, you will see that there are items on
there for replacing that item in its location ("Modify this structure slot"),
and for tracing modifications to that location ("Monitor this
location").

These operations are available on Mouse Right independently of whether
the value is suitable for the context.  If you have any ideas for how to
highlight something as being available on some of the mouse keys without
being available on others, I'm sure the people at Symbolics would still
be glad to hear them!

However, it is a bug that you are offered the ability to modify the
stack-frame slot after exiting the debugger.  The symbol BREAK should
still be sensitive, but not the list (BREAK).