* Why do replace commands sometimes not work? @ 2012-05-24 23:15 MBR 0 siblings, 0 replies; 4+ messages in thread From: MBR @ 2012-05-24 23:15 UTC (permalink / raw) To: help-gnu-emacs, help-emacs-windows [-- Attachment #1: Type: text/plain, Size: 4670 bytes --] There's a problem I've encountered with Emacs for many years. I never reported it because I've been running Emacs 21.3 under Windows, and I figured that Emacs users on Windows are probably a very small percentage of Emacs users, and that 21.3 is so old that it nobody would be interested in debugging the problem. But then I encountered the same problem with Emacs 23.2.1 running under Linux. And a few days ago I finally installed Windows Emacs 23.4.1, and it's got the same problem. The problem: the replace commands, M-x replace-string and M-x replace-regexp, sometimes work and sometimes don't. When it doesn't work, it often will work if I retype exactly the same command a few times. My reaction when I first encountered the problem was that I must have mistyped the command the first time. But I've encountered it for so many years that whenever it fails to work the first time, it's become habit for me to be extremely careful in my typing the second and subsequent times, and it often fails on those tries too, but eventually succeeds. I particularly notice it when I'm defining a macro [ delimited by C-x ( and C-x ) ]. And frequently I have the buffer narrowed to a small subset of text that I want to operate on. But I don't know for certain that defining a macro or having the buffer narrowed are what cause the problem to manifest. I now have a concrete example of this that proves that it's not due to my mistyping. There's a point in the macro where the buffer has been narrowed to a portion that contains a symbol in CamelCase. Note: In case you're unfamiliar with CamelCase, it's a convention for variable names originally popularized by the X Window System. Earlier conventions for C and C++ used "_" as a word delimiter within variable names. Lisp used "-" instead of "_". CamelCase, so-called because the capital letters in the middle of the word form humps like those on a camel's back, uses capital letters to indicate the beginning of a new word. So, the C-style variable name find_char_in_string, or Lisp-style variable name find-char-in-string, in CamelCase is findCharInString. The purpose of this part of the macro is to turn CamelCase into space-separated words. M-< ;; Go to beginning of narrowed buffer M-x replace-regexp RET [A-Z] RET ;; Find any capital letter C-q SPC \& RET ;; Replace it with a space followed by itself M-< ;; Go to beginning of narrowed buffer C-d ;; Delete the unwanted space before the first letter So, if the narrowed portion of the buffer contains: "JohnJacobJingleheimerschmidt" after running this portion of the macro, it should contain: "John Jacob Jingleheimerschmidt" Instead, when run in Emacs 23, the result is: "ohnJacobJingleheimerschmidt" which is exactly what you'd expect if the M-x replace-regexp failed to do the replacement that it should have. But since I know that sometimes a replace command works the second time after failing to work the first time, I modified that portion of the macro to do the replace twice: M-< ;; Go to beginning of narrowed buffer M-x replace-regexp RET [A-Z] RET ;; Find any capital letter C-q SPC \& RET ;; Replace it with a space followed by itself M-< ;; Go to beginning of narrowed buffer M-x replace-regexp RET [A-Z] RET ;; Find any capital letter C-q SPC \& RET ;; Replace it with a space followed by itself M-< ;; Go to beginning of narrowed buffer C-d ;; Delete the unwanted space before the first letter Now, if the replace were working the first time, applying it again would produce the undesired result: " John Jacob Jingleheimerschmidt" Instead, it produces: "John Jacob Jingleheimerschmidt" Does anybody here have any idea what's going wrong here? Mark Rosenthal mbr@arlsoft.com <mailto:mbr@arlsoft.com> P.S. - One further clue: In the older version of Emacs (21.3) I've noticed that at those times when the replace fails to work, if I repeat the replace command with C-x ESC ESC, the minibuffer shows: (replace-regexp "[A-Z]" " \\&" nil sss eee) where sss and eee are integers that are supposed to indicate the beginning and end characters of the region to operate on, but when the replace has failed, sss and eee specify a small subset of the region. [-- Attachment #2: Type: text/html, Size: 7382 bytes --] ^ permalink raw reply [flat|nested] 4+ messages in thread
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* Re: Why do replace commands sometimes not work? [not found] ` <5O-dnbLCNdm5bCPSnZ2dnUVZ5rmdnZ2d@giganews.com> @ 2012-05-25 3:01 ` MBR 2012-05-25 12:25 ` Ludwig, Mark 2012-05-25 15:36 ` Barry Margolin 1 sibling, 1 reply; 4+ messages in thread From: MBR @ 2012-05-25 3:01 UTC (permalink / raw) To: B. T. Raven; +Cc: help-gnu-emacs [-- Attachment #1: Type: text/plain, Size: 1157 bytes --] On 5/24/2012 10:41 PM, B. T. Raven wrote: > I can't reproduce that misbehavior on w32 ver 23.1 > Both in *scratch* (lisp mode) and a junk file in text mode I get: > > John Jacob Jingleheimerschmidt > " John Jacob Jingleheimerschmidt" > " John Jacob Jingleheimerschmidt" > John Jacob Jingleheimerschmidt > John Jacob Jingleheimerschmidt > > where the second and third lines were originally camel-case in quotes. > I did assign the macro to a keychord with C-xC-kb > > Ed I'm not surprised that you can't reproduce it. It's so unpredictable that it reminds me of an assembly language bug I diagnosed many years ago where the code turned out to be making a critical decision based on data it fetched from an uninitialized memory location. In the case of this bug, the state of memory could depend on every keystroke I've typed since I started Emacs, the contents of every file it's opened, etc. The example I gave was to illustrate the sort of problem I'm running into, to see if anyone else has encountered the same problem. I'd be thrilled if I could come up with a reproducible example, but I've had no luck on that front so far. Mark [-- Attachment #2: Type: text/html, Size: 1540 bytes --] ^ permalink raw reply [flat|nested] 4+ messages in thread
* RE: Why do replace commands sometimes not work? 2012-05-25 3:01 ` MBR @ 2012-05-25 12:25 ` Ludwig, Mark 0 siblings, 0 replies; 4+ messages in thread From: Ludwig, Mark @ 2012-05-25 12:25 UTC (permalink / raw) To: MBR, B. T. Raven; +Cc: help-gnu-emacs@gnu.org [-- Attachment #1: Type: text/plain, Size: 1548 bytes --] I assume something like Valgrind has been applied to Emacs ... and it's clean. Cheers, Mark From: help-gnu-emacs-bounces+ludwig.mark=siemens.com@gnu.org [mailto:help-gnu-emacs-bounces+ludwig.mark=siemens.com@gnu.org] On Behalf Of MBR Sent: Thursday, May 24, 2012 10:01 PM To: B. T. Raven Cc: help-gnu-emacs@gnu.org Subject: Re: Why do replace commands sometimes not work? On 5/24/2012 10:41 PM, B. T. Raven wrote: I can't reproduce that misbehavior on w32 ver 23.1 Both in *scratch* (lisp mode) and a junk file in text mode I get: John Jacob Jingleheimerschmidt " John Jacob Jingleheimerschmidt" " John Jacob Jingleheimerschmidt" John Jacob Jingleheimerschmidt John Jacob Jingleheimerschmidt where the second and third lines were originally camel-case in quotes. I did assign the macro to a keychord with C-xC-kb Ed I'm not surprised that you can't reproduce it. It's so unpredictable that it reminds me of an assembly language bug I diagnosed many years ago where the code turned out to be making a critical decision based on data it fetched from an uninitialized memory location. In the case of this bug, the state of memory could depend on every keystroke I've typed since I started Emacs, the contents of every file it's opened, etc. The example I gave was to illustrate the sort of problem I'm running into, to see if anyone else has encountered the same problem. I'd be thrilled if I could come up with a reproducible example, but I've had no luck on that front so far. Mark [-- Attachment #2: Type: text/html, Size: 5319 bytes --] ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Why do replace commands sometimes not work? [not found] ` <5O-dnbLCNdm5bCPSnZ2dnUVZ5rmdnZ2d@giganews.com> 2012-05-25 3:01 ` MBR @ 2012-05-25 15:36 ` Barry Margolin 1 sibling, 0 replies; 4+ messages in thread From: Barry Margolin @ 2012-05-25 15:36 UTC (permalink / raw) To: help-gnu-emacs In article <5O-dnbLCNdm5bCPSnZ2dnUVZ5rmdnZ2d@giganews.com>, "B. T. Raven" <nihil@nihilo.net> wrote: > Die Thu May 24 2012 18:15:40 GMT-0500 (Central Daylight Time) MBR > <mbr@arlsoft.com> scripsit: > > > There's a problem I've encountered with Emacs for many years. I never > > reported it because I've been running Emacs 21.3 under Windows, and I > > figured that Emacs users on Windows are probably a very small percentage > > of Emacs users, and that 21.3 is so old that it nobody would be > > interested in debugging the problem. > > > > But then I encountered the same problem with Emacs 23.2.1 running under > > Linux. And a few days ago I finally installed Windows Emacs 23.4.1, and > > it's got the same problem. > > > > The problem: the replace commands, M-x replace-string and M-x > > replace-regexp, sometimes work and sometimes don't. When it doesn't > > work, it often will work if I retype exactly the same command a few times. > > > > My reaction when I first encountered the problem was that I must have > > mistyped the command the first time. But I've encountered it for so > > many years that whenever it fails to work the first time, it's become > > habit for me to be extremely careful in my typing the second and > > subsequent times, and it often fails on those tries too, but eventually > > succeeds. > > > > I particularly notice it when I'm defining a macro [ delimited by C-x ( > > and C-x ) ]. And frequently I have the buffer narrowed to a small > > subset of text that I want to operate on. But I don't know for certain > > that defining a macro or having the buffer narrowed are what cause the > > problem to manifest. > > > > I now have a concrete example of this that proves that it's not due to > > my mistyping. There's a point in the macro where the buffer has been > > narrowed to a portion that contains a symbol in CamelCase. > > > > Note: In case you're unfamiliar with CamelCase, it's a convention > > for variable names originally popularized by the X Window System. > > Earlier conventions for C and C++ used "_" as a word delimiter > > within variable names. Lisp used "-" instead of "_". CamelCase, > > so-called because the capital letters in the middle of the word form > > humps like those on a camel's back, uses capital letters to indicate > > the beginning of a new word. So, the C-style variable name > > find_char_in_string, or Lisp-style variable name > > find-char-in-string, in CamelCase is findCharInString. > > > > The purpose of this part of the macro is to turn CamelCase into > > space-separated words. > > > > M-< ;; Go to beginning of narrowed buffer > > M-x replace-regexp RET > > [A-Z] RET ;; Find any capital letter > > C-q SPC \& RET ;; Replace it with a space followed by itself > > M-< ;; Go to beginning of narrowed buffer > > C-d ;; Delete the unwanted space before the > > first letter > > > > So, if the narrowed portion of the buffer contains: > > > > "JohnJacobJingleheimerschmidt" > > > > after running this portion of the macro, it should contain: > > > > "John Jacob Jingleheimerschmidt" > > > > Instead, when run in Emacs 23, the result is: > > > > "ohnJacobJingleheimerschmidt" > > > > which is exactly what you'd expect if the M-x replace-regexp failed to > > do the replacement that it should have. But since I know that sometimes > > a replace command works the second time after failing to work the first > > time, I modified that portion of the macro to do the replace twice: > > > > M-< ;; Go to beginning of narrowed buffer > > M-x replace-regexp RET > > [A-Z] RET ;; Find any capital letter > > C-q SPC \& RET ;; Replace it with a space followed by itself > > M-< ;; Go to beginning of narrowed buffer > > M-x replace-regexp RET > > [A-Z] RET ;; Find any capital letter > > C-q SPC \& RET ;; Replace it with a space followed by itself > > M-< ;; Go to beginning of narrowed buffer > > C-d ;; Delete the unwanted space before the > > first letter > > > > Now, if the replace were working the first time, applying it again would > > produce the undesired result: > > > > " John Jacob Jingleheimerschmidt" > > > > Instead, it produces: > > > > "John Jacob Jingleheimerschmidt" > > > > Does anybody here have any idea what's going wrong here? > > > > Mark Rosenthal > > mbr@arlsoft.com <mailto:mbr@arlsoft.com> > > > > P.S. - One further clue: In the older version of Emacs (21.3) I've > > noticed that at those times when the replace fails to work, if I repeat > > the replace command with C-x ESC ESC, the minibuffer shows: > > > > (replace-regexp "[A-Z]" " \\&" nil sss eee) > > > > where sss and eee are integers that are supposed to indicate the > > beginning and end characters of the region to operate on, but when the > > replace has failed, sss and eee specify a small subset of the region. > > > > > I can't reproduce that misbehavior on w32 ver 23.1 > Both in *scratch* (lisp mode) and a junk file in text mode I get: > > John Jacob Jingleheimerschmidt > " John Jacob Jingleheimerschmidt" > " John Jacob Jingleheimerschmidt" > John Jacob Jingleheimerschmidt > John Jacob Jingleheimerschmidt > > where the second and third lines were originally camel-case in quotes. > I did assign the macro to a keychord with C-xC-kb I think the clue is in his P.S. If you have transient-mark-mode enabled, the replace commands restrict themselves to the active region. When I run M-ESC ESC in Emacs 22.2, it doesn't show explicit buffer positions, it show things like (if (and transient-mark-mode mark-active) (region-beginning)). But maybe in the older version it just put the buffer positions in the history. -- Barry Margolin, barmar@alum.mit.edu Arlington, MA *** PLEASE post questions in newsgroups, not directly to me *** ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2012-05-25 15:36 UTC | newest] Thread overview: 4+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2012-05-24 23:15 Why do replace commands sometimes not work? MBR [not found] <mailman.1636.1337901354.855.help-gnu-emacs@gnu.org> [not found] ` <5O-dnbLCNdm5bCPSnZ2dnUVZ5rmdnZ2d@giganews.com> 2012-05-25 3:01 ` MBR 2012-05-25 12:25 ` Ludwig, Mark 2012-05-25 15:36 ` Barry Margolin
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