From: Stefan Monnier <monnier@iro.umontreal.ca>
To: Kelly Dean <kelly@prtime.org>
Cc: emacs-devel@gnu.org
Subject: Re: [PATCH] (Updated) Run hook when variable is set
Date: Sun, 22 Feb 2015 23:19:00 -0500 [thread overview]
Message-ID: <jwvlhjpgur6.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <BfQSUZTrbI1g5mSYVjwxD3NUaUJnJ8FUyh3T3fVgyZe@local> (Kelly Dean's message of "Mon, 23 Feb 2015 03:09:17 +0000")
>> I'm sorry, but I consider this a form of lying. It makes it sound like
>> "the new var-hook functionality actually speeds things up", even though
>> it's not this new functionality but some unrelated (tho bundled) change
>> which does it (and which could be applied independently).
> I didn't say the varhook functionality speeds things up. I explicitly said
> it has performance costs, and I found optimization opportunities to _pay
> for_ those costs.
I know. I said "makes it sound like".
> I was completely honest about what I did,
You were, indeed.
>> The issue is not patch size per se, but just keeping the patch focused
>> on its core purpose.
> The constant-hooked combination is an optimization,
I don't consider it an optimization. I consider the functionality to be
an extension of the "constant" bit into a more nuanced 3-valued field.
> The patch could be applied to trunk without that optimization,
No because it's fundamentally wrong to have `constant' in one field and
`hooked' in another when `hooked' can only be used when constant==0.
> Fine, but adding the capability of converting setq, etc into makunbound has
> the cost of breaking correctness (because hooking a symbol would change the
> behavior of (setq foo void-sentinel)), not just the cost of enabling user
> errors.
I think that would be OK because (setq foo void-sentinel) can be
considered as erroneous code.
This said, I don't care very much about allowing/disallowing a setq to
turn into a makunbound. I think it's not worth spending any code on this,
so I similarly shouldn't spend much time arguing about it.
> Magic constants added back in to the source code, just to avoid
> touching a few lines of code in the patch.
Actually, this is a mistake. Using 1 was OK back when the code was
written (it should be `true' instead nowadays), but with the new
definition of the field, it should be SYM_CONST.
> This version of the patch slows down Emacs.
How much, where, and why? Clearly, there is an added cost in the
unbind_to case since we now have to check sym->constant, but otherwise,
where the extra cost come from? Is it just the extra `env' argument to
set_internal?
> IIUC, I've made all the changes you requested.
Indeed, thank you. See included the remaining nitpicks below.
The only significant comments below is the one about the ENV arg, since
I think we really should be able to distinguish all buffer-local changes
from the non-buffer-local ones (I think this is more important than
distinguishing `setq' to the toplevel value vs `setq' within a `let',
which we could even distinguish without any special ENV value by
exporting let_shadows_buffer_binding_p and/or
let_shadows_global_binding_p to Elisp).
Stefan
> +SYMBOL is the symbol being set. ENV is the environment is which it's being
> +set.
Actually, ENV is not an environment (it's just a symbol which describes
in which environment the modification is made).
> +The possible values of ENV are these symbols, with these meanings:
> +global: The global environment.
So, this is for a `setq-default' or a `setq' when there's no
buffer-local value, and no active let-binding.
> +buf-local: The setter's buffer-local environment. ENV is this value if the
> +setter sets the buffer-local variable.
So, IIUC this is for a `setq' when the variable has been made buffer
local in this buffer.
And IIUC this is for the case where there's no active let-binding for
this variable, right?
Does it distinguish between let-bindings for the buffer-local part of
this variable, and let-bindings for other parts of the variable (e.g. in
other buffers, or let-binding for the global part of the var)?
> +dyn-local: The innermost dynamic environment in which SYMBOL is bound. ENV
> +is this value if the setter sets a dynamic local variable.
IIUC this is for a `setq' to a variable that has an active let-binding.
Does it distinguish between the case where the let-binding is
buffer-local and where it isn't?
> +dyn-bind: A new dynamic environment. ENV is this value if the setter creates
> +a new dynamic environment, such as by using `let'.
This is for a `let'. But IIUC we don't get to know if this let is
buffer-local or global, right?
> +to NEWVAL, return NEWVAL. To block the attempt, and leave the variable
^^^
BTW, we use the `sentence-end-double-space' convention in our comments
and docstrings.
> +is the value of symbol-hook-void-value but NEWVAL is not, you can
^^^^^^^^^^^^^^^^^^^^^^
Please wrap this in `...' so C-h f can turn it into a hyperlink.
> + doc: /* Return t if SYMBOL is hooked.
^^^
We usually prefer to say "non-nil" for such predicate return value (and
callers shouldn't assume that it's necessarily t).
Stefan
next prev parent reply other threads:[~2015-02-23 4:19 UTC|newest]
Thread overview: 110+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-20 2:54 Proposal to change cursor appearance to indicate region activation Kelly Dean
2013-04-20 7:23 ` Drew Adams
2015-01-22 5:38 ` [PATCH] " Kelly Dean
2015-01-22 14:25 ` Stefan Monnier
2015-01-23 3:08 ` [PATCH] " Kelly Dean
2015-01-23 4:55 ` Stefan Monnier
2015-01-23 11:07 ` Kelly Dean
2015-01-23 17:49 ` Drew Adams
2015-01-24 3:06 ` Kelly Dean
2015-01-24 4:52 ` Stefan Monnier
2015-01-24 9:22 ` Kelly Dean
2015-01-25 14:29 ` Stefan Monnier
2015-01-28 9:15 ` [PATCH] Run hook when variable is set Kelly Dean
2015-01-28 9:23 ` [PATCH] Proposal to change cursor appearance to indicate region activation Kelly Dean
2015-01-28 11:24 ` David Kastrup
2015-01-28 12:13 ` David Kastrup
2015-01-29 10:46 ` Kelly Dean
2015-01-29 11:16 ` David Kastrup
2015-01-30 7:20 ` Kelly Dean
2015-01-30 9:19 ` David Kastrup
2015-01-30 10:05 ` Kelly Dean
2015-01-30 10:12 ` David Kastrup
2015-01-30 9:43 ` Kelly Dean
2015-01-28 19:25 ` [PATCH] Run hook when variable is set Stefan Monnier
2015-01-29 8:20 ` Kelly Dean
2015-01-29 8:28 ` Lars Ingebrigtsen
2015-01-29 14:58 ` Stefan Monnier
2015-01-30 7:34 ` Kelly Dean
2015-01-30 15:55 ` Stefan Monnier
2015-01-31 9:18 ` Kelly Dean
2015-01-31 20:48 ` Stefan Monnier
2015-02-02 5:40 ` Kelly Dean
2015-02-02 15:57 ` Stefan Monnier
2015-02-03 19:56 ` Kelly Dean
2015-02-03 22:49 ` Stefan Monnier
2015-02-05 3:10 ` [PATCH] (Updated) " Kelly Dean
2015-02-05 13:57 ` Stefan Monnier
2015-02-06 5:34 ` Kelly Dean
2015-02-06 14:42 ` Stefan Monnier
2015-02-07 12:27 ` Kelly Dean
2015-02-07 15:09 ` Stefan Monnier
2015-02-09 3:24 ` Kelly Dean
2015-02-12 19:58 ` Stefan Monnier
2015-02-13 23:08 ` Kelly Dean
2015-02-14 0:55 ` Stefan Monnier
2015-02-14 22:19 ` Kelly Dean
2015-02-15 20:25 ` Stefan Monnier
2015-02-17 2:22 ` Kelly Dean
2015-02-17 23:07 ` Richard Stallman
2015-02-18 3:19 ` The purpose of makunbound (Was: Run hook when variable is set) Kelly Dean
2015-02-18 5:48 ` The purpose of makunbound Stefan Monnier
2015-02-18 8:51 ` Kelly Dean
2015-02-18 14:34 ` Stefan Monnier
2015-02-18 18:53 ` Kelly Dean
2015-02-18 22:42 ` Stefan Monnier
2015-02-19 10:36 ` Kelly Dean
2015-02-22 0:18 ` Kelly Dean
2015-02-19 10:45 ` Kelly Dean
2015-02-19 13:33 ` Stefan Monnier
2015-02-19 23:51 ` Kelly Dean
2015-02-20 1:59 ` Stefan Monnier
2015-02-20 9:35 ` Kelly Dean
2015-02-20 16:55 ` Stefan Monnier
2015-02-20 2:58 ` Stephen J. Turnbull
2015-02-20 0:56 ` Richard Stallman
2015-02-20 9:02 ` Kelly Dean
2015-02-20 15:41 ` Richard Stallman
2015-02-21 5:45 ` Stephen J. Turnbull
2015-02-22 0:32 ` Kelly Dean
2015-02-22 8:45 ` Andreas Schwab
2015-02-18 5:15 ` [PATCH] (Updated) Run hook when variable is set Kelly Dean
2015-02-18 22:37 ` Stefan Monnier
2015-02-18 22:37 ` Stefan Monnier
2015-02-19 10:35 ` Kelly Dean
2015-02-19 13:30 ` Stefan Monnier
2015-02-20 6:48 ` Kelly Dean
2015-02-20 19:29 ` Stefan Monnier
2015-02-21 14:18 ` Kelly Dean
2015-02-21 20:51 ` Stefan Monnier
2015-02-22 0:32 ` Kelly Dean
2015-02-22 10:40 ` Stephen J. Turnbull
2015-02-22 21:35 ` Stefan Monnier
2015-02-23 3:09 ` Kelly Dean
2015-02-23 4:19 ` Stefan Monnier [this message]
2015-02-20 20:27 ` Proposal for debugging/testing option Kelly Dean
2015-02-24 16:28 ` Stefan Monnier
2015-02-14 20:37 ` [PATCH] (Updated) Run hook when variable is set Johan Bockgård
2015-02-15 19:36 ` Stefan Monnier
2015-02-15 19:53 ` Patches: inline vs. attachment, compressed vs. uncompressed. [was: Run hook when variable is set] Alan Mackenzie
2015-02-06 9:55 ` [PATCH] (Updated) Run hook when variable is set Kelly Dean
2015-01-30 23:29 ` [PATCH] " Richard Stallman
2015-01-31 9:23 ` Kelly Dean
2015-01-31 23:16 ` Richard Stallman
2015-02-02 5:41 ` Kelly Dean
2015-02-01 2:04 ` Alexis
2015-02-01 4:05 ` Stefan Monnier
2015-02-01 8:58 ` David Kastrup
2015-01-29 16:06 ` Eli Zaretskii
2015-01-30 7:14 ` Kelly Dean
2015-01-30 9:08 ` Eli Zaretskii
2015-01-23 20:34 ` [PATCH] Proposal to change cursor appearance to indicate region activation Stefan Monnier
2015-01-24 0:25 ` Kelly Dean
2015-01-23 10:01 ` Tassilo Horn
2015-01-23 17:49 ` Drew Adams
2015-01-23 10:06 ` Eli Zaretskii
2015-01-23 11:40 ` Kelly Dean
2015-01-23 11:56 ` Eli Zaretskii
2015-01-22 5:41 ` Kelly Dean
2013-11-23 13:34 ` Stefan Monnier
2013-11-23 20:25 ` Drew Adams
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