From: Marcin Borkowski <mbork@wmi.amu.edu.pl>
To: Drew Adams <drew.adams@oracle.com>, help-gnu-emacs@gnu.org
Subject: Re: Advice on troubleshooting function to "unscroll"
Date: Mon, 26 Jan 2015 00:15:53 +0100 [thread overview]
Message-ID: <87vbjufo46.fsf@wmi.amu.edu.pl> (raw)
In-Reply-To: <54C5748E.4060605@gmail.com>
On 2015-01-25, at 23:56, Will Monroe <wtmonroe.ls@gmail.com> wrote:
> On 01/25/2015 04:45 PM, Drew Adams wrote:
>>
>> The command `scroll-up' is indeed older, and it is still usable.
>> It is, in fact, the core of the `scroll-up-command' implementation.
>
> Interesting. Given what the author's assumptions of how 'scroll-up'
> should work and how the newer 'scroll-up-command' seems to share some,
> but not all, of that functionality, it would probably be interesting to
> see where they differ. I may not be expressing this clearly, but you've
> helped to clarify the question I want to answer to be: "why did
> scroll-up-command work where the still useful but not appropriate
> scroll-up did not?"
That's why it's useful to say
M-x find-function RET scroll-up-command RET!
>>> I've hesitated from diving into Edebug because there was no
>>> "error" as such. That is, the code "worked" it just didn't do
>>> what I intended.
>>
>> Using the debugger (and debugging generally) is not necessarily
>> about finding why Emacs raises a particular error. (That is the
>> particular use of variable `debug-on-error': enter the debugger
>> to show a backtrace when an error is raised.)
>>
>> In addition to Edebug, there is the regular Emacs debugger, aka
>> `debug'. Some of us prefer to use that. Others prefer to use
>> it in some cases but `edebug' in other cases.
Thanks, Drew, for mentioning that!
>> Keep in mind too that any debugger does not necessarily tell you
>> everything that goes on, and its representation of what happens
>> with debugging turned off is not flawless. In particular, this
>> is because using the debugger itself changes what Emacs does.
>> (Think of the debugger's buffer display and its handling of
>> input events, for example.)
>>
>> The regular debugger is what you get with `debug-on-entry' and
>> by inserting calls to `(debug)' in code to serve more or less as
>> breakpoints. See `C-h f debug' for information about evaluating
>> and displaying the results of sexps (cdr ARGS) upon entry into
>> the debugger.
I do not like the (debug) approach, since it seems to be less
newbie-friendly. It is true, of course, that Edebug does not always
work as intended.
> This is very helpful stuff to consider as I begin to think about what I
> want to accomplish when using Edebug or debugger.
>
> And if I'm being honest about why I did not go to Edebug it's because I
> was anticipating great difficulty reading the backtrace statements. I
> thought my problem might be compounded by a more general illiteracy in
> that regard...
Now I'm starting to think that it would be nice to study the backtraces
once and for all and write about them (for myself and for others)...
> Thanks again, Drew. A really helpful answer!
Me too!
> Will
Best,
--
Marcin Borkowski
http://octd.wmi.amu.edu.pl/en/Marcin_Borkowski
Faculty of Mathematics and Computer Science
Adam Mickiewicz University
next prev parent reply other threads:[~2015-01-25 23:15 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-25 20:52 Advice on troubleshooting function to "unscroll" Will Monroe
2015-01-25 21:35 ` Marcin Borkowski
2015-01-25 21:43 ` Will Monroe
2015-01-25 21:55 ` Marcin Borkowski
2015-01-25 22:01 ` Will Monroe
2015-01-25 21:45 ` Marcin Borkowski
2015-01-25 22:03 ` Will Monroe
2015-01-25 22:09 ` Marcin Borkowski
2015-01-25 22:45 ` Drew Adams
2015-01-25 22:56 ` Will Monroe
2015-01-25 23:15 ` Marcin Borkowski [this message]
2015-01-26 0:03 ` Drew Adams
2015-01-26 0:16 ` Marcin Borkowski
2015-01-26 1:06 ` Drew Adams
2015-01-26 1:17 ` Will Monroe
2015-01-26 1:21 ` Marcin Borkowski
2015-01-26 1:33 ` Drew Adams
[not found] <mailman.18583.1422219396.1147.help-gnu-emacs@gnu.org>
2015-01-25 21:35 ` Joost Kremers
2015-01-25 21:57 ` Will Monroe
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