[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
bug#65051: internal_equal manipulates symbols with position without chec
From: |
Alan Mackenzie |
Subject: |
bug#65051: internal_equal manipulates symbols with position without checking symbols-with-pos-enabled. |
Date: |
Fri, 11 Aug 2023 14:04:59 +0000 |
Hello, Dmitry.
On Fri, Aug 11, 2023 at 16:19:47 +0300, Dmitry Gutov wrote:
> Hi again, Alan,
> On 11/08/2023 15:05, Alan Mackenzie wrote:
> >>> I think it was possibly a design error to have text
> >>> properties conceptually as a part of a string/buffer rather than
> >>> something associated with it, like an overlay. The fact that equal
> >>> ignores these properties supports this view.
> >> We needed a reference to access the properties from. Overlays are
> >> different because they attach to a buffer. There is nothing else to
> >> attach to when you have a string value.
> > This is arbitrary; overlays _could_ have been made attachable to
> > strings, in which case text properties need not have been. That would
> > have prevented all the heart searching when considering equal with
> > strings.
> Then we would have some "metadata" that's part of the value, and some
> that is not part of the value. How would we look those up, though?
> Through a global registry?
> equal-including-properties is useful enough, by the way. In the tests,
> at least.
Yes.
> >> Which seems very similar to the situation with symbols, I think.
> > There are practical differences. Having symbols with position simply
> > handled as their bare symbols would slow down Emacs quite a lot. That's
> > why we have symbols-with-pos-enabled. But you know that.
> Does the current impl of 'equal' create worse performance as well? That
> would be a good argument to change it.
Yes, but unmeasurably so. The current implementation has two
comparisons, quite complicated, where only one simple one is needed, for
the typical use-case.
> > Currently, the working of s-w-p-enabled is inconsistent, and
> > should be fixed, which is what this bug is about.
> Inconsistent with what?
With its definition: when s-w-p-enabled is non-nil, SWPs are handled
specially. When it's nil, they're not (or, at least, shouldn't be).
> If we're talking about the relation between EQUAL and EQ, objects that
> are EQ have to be EQUAL, but those that are EQUAL don't have to be EQ.
I wasn't talking about that relationship, no, but there is no danger to
it in fixing the current bug (or, indeed, in leaving it unfixed).
> Anyway, I'd like to offer a question from a different perspective:
> should two symbols-with-positions where the positions are different but
> the symbol is the same, be equal between each other?
Yes, when and only when symbols-with-pos-enabled is non-nil.
> If yes (which is my reading of fns.c:2755), then it makes sense for
> them to be equal-able to symbols without positions as well.
Again, this should be the case when s-w-p-enabled is non-nil and only
then.
--
Alan Mackenzie (Nuremberg, Germany).
- bug#65051: internal_equal manipulates symbols with position without checking symbols-with-pos-enabled., (continued)
- bug#65051: internal_equal manipulates symbols with position without checking symbols-with-pos-enabled., Alan Mackenzie, 2023/08/08
- bug#65051: internal_equal manipulates symbols with position without checking symbols-with-pos-enabled., Stefan Monnier, 2023/08/09
- bug#65051: internal_equal manipulates symbols with position without checking symbols-with-pos-enabled., Alan Mackenzie, 2023/08/10
- bug#65051: internal_equal manipulates symbols with position without checking symbols-with-pos-enabled., Stefan Monnier, 2023/08/10
- bug#65051: internal_equal manipulates symbols with position without checking symbols-with-pos-enabled., Alan Mackenzie, 2023/08/10
- bug#65051: internal_equal manipulates symbols with position without checking symbols-with-pos-enabled., Dmitry Gutov, 2023/08/10
- bug#65051: internal_equal manipulates symbols with position without checking symbols-with-pos-enabled., Alan Mackenzie, 2023/08/11
- bug#65051: internal_equal manipulates symbols with position without checking symbols-with-pos-enabled., Dmitry Gutov, 2023/08/11
- bug#65051: internal_equal manipulates symbols with position without checking symbols-with-pos-enabled., Alan Mackenzie, 2023/08/11
- bug#65051: internal_equal manipulates symbols with position without checking symbols-with-pos-enabled., Dmitry Gutov, 2023/08/11
- bug#65051: internal_equal manipulates symbols with position without checking symbols-with-pos-enabled.,
Alan Mackenzie <=
- bug#65051: internal_equal manipulates symbols with position without checking symbols-with-pos-enabled., Dmitry Gutov, 2023/08/11