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Re: On Tabs and Spaces

From
Robin Rosenberg <robin.rosenberg.lists@dewire.com>
Date
Oct 20, 2007, 13:54 UTC
Message-ID
<200710201554.16576.robin.rosenberg.lists@dewire.com>
In-Reply-To
<634393B0-734A-4884-93E3-42F7D3CB157F@mit.edu>
tisdag 16 oktober 2007 skrev Michael Witten:
Show 9 quoted lines
> What are the rules about tabs and spaces in source code?
> 
> I'm having a terrible time with formatting,
> especially in the perl scripts; there is a
> mix of spaces and tabs.
> 
> from what I can deduce, single tabs are used
> to introduce the equivalent of 8 spaces while
> 4 explicit spaces are used for half a tab.

A looong time ago I worked with a system that did not have *this* problem. The code had a straight left margin. No indent. The code was initially written just after the origin of time_t (content, not name) and that it was written on punched cards probably explains the left margin, efter all you can indent the cards if you like to.

I "accidentally" did indent code once, but only once, since I got a lot of complains from others about not following coding standards. My solution was to write a Brief macro to indent the code before working on it and undent before submitting my work to test. We never had a discussion on tabs vs spaces.

Btw, some of that code was "logically" indented 22 levels. I'm still amazed att those long sheets of code people annotated with pencil to discover the logical structure.

So it is possble to simply not care about tabs and spaces, except where there is a syntactic difference.

Fast-formward twenty years and back to the topic.

I think it is ok to start or end a *big* series of changes with a re-format patch, iff the series already introduces a *lot* of changes.

In the previously submitted and rejected patch to cvsexportcommit this was not the case, I rewrote it heavily and that would have been a window for for reformatting, but I didn't see a need, probably because I used emacs and probably the original author too. Now I realize the file *is* actually indented inconsistently. Add to that that I am responsible for some of it. Next person to do any major work on it should submit a fix-indentation patch very much like the one MIchael did. The problem with reviewing such patches still exists, it is not possible to just read such patches, one has to apply them and verify them with other tools.

I've been through enough many bracket and indentation discussions to see that it really doesn't matter as much what style is used as long as the same style is used throughout a whole source file. There are some coding styles that works bad with the patch/apply style submitting code, but those are not an issue here.

As for TAB size. The most authoritative read "stupid") programs on the issue, i.e. cat (unix) and type (dos/windows) agree that tab stops are located at every eight position starting (8,16 etc).

Attached is an updated version of a script I've been using lately to clean up commits. First it only removed trailing whitespace, but after this thread I changed it to (try to) tabify changes. Should we use such scripts more actively to root out inconsistencies a patch at a time?

-- robin
Previous: Andreas Ericsson
Message 100 of 100 in “On Tabs and Spaces”
  1. Michael WittenOct 16, 2007
  2. Shawn O. PearceOct 16, 2007
  3. Michael WittenOct 16, 2007
  4. Andreas EricssonOct 16, 2007
  5. Sam RavnborgOct 16, 2007
  6. Petr BaudisOct 16, 2007
  7. DavidOct 17, 2007
  8. Andy ParkinsOct 17, 2007
  9. Adam PiatyszekOct 16, 2007
  10. Lars HjemliOct 16, 2007
  11. Adam PiatyszekOct 16, 2007
  12. Jeffrey C. OllieOct 16, 2007
  13. Michael WittenOct 16, 2007
  14. Jari AaltoOct 16, 2007
  15. Linus TorvaldsOct 16, 2007
  16. Mike HommeyOct 16, 2007
  17. Linus TorvaldsOct 16, 2007
  18. Linus TorvaldsOct 16, 2007
  19. Matthieu MoyOct 16, 2007
  20. Tom TobinOct 16, 2007
  21. Linus TorvaldsOct 16, 2007
  22. Christer WeinigelOct 16, 2007
  23. Linus TorvaldsOct 17, 2007
  24. Michael WittenOct 17, 2007
  25. Linus TorvaldsOct 17, 2007
  26. Luke LuOct 17, 2007
  27. Michael WittenOct 17, 2007
  28. Luke LuOct 17, 2007
  29. Nikolai WeibullOct 17, 2007
  30. Michael WittenOct 17, 2007
  31. Jari AaltoOct 17, 2007
  32. Andreas EricssonOct 17, 2007
  33. Jari AaltoOct 17, 2007
  34. Dmitry TorokhovOct 18, 2007
  35. Jari AaltoOct 18, 2007
  36. Petr BaudisOct 18, 2007
  37. Nikolai WeibullOct 18, 2007
  38. Miles BaderOct 22, 2007
  39. David KågedalOct 18, 2007
  40. Mike HommeyOct 18, 2007
  41. Jari AaltoOct 18, 2007
  42. Linus TorvaldsOct 17, 2007
  43. Johannes SchindelinOct 17, 2007
  44. Tom TobinOct 17, 2007
  45. Linus TorvaldsOct 17, 2007
  46. Tom TobinOct 17, 2007
  47. Linus TorvaldsOct 17, 2007
  48. Nicolas PitreOct 17, 2007
  49. Josh EnglandOct 17, 2007
  50. Linus TorvaldsOct 17, 2007
  51. Christer WeinigelOct 17, 2007
  52. Linus TorvaldsOct 17, 2007
  53. David KastrupOct 18, 2007
  54. Johannes SchindelinOct 17, 2007
  55. Christer WeinigelOct 17, 2007
  56. Johannes SchindelinOct 17, 2007
  57. Christer WeinigelOct 18, 2007
  58. Andreas EricssonOct 18, 2007
  59. David KågedalOct 18, 2007
  60. Linus TorvaldsOct 17, 2007
  61. David KastrupOct 17, 2007
  62. Johannes SchindelinOct 17, 2007
  63. Jan WielemakerOct 17, 2007
  64. Jeff KingOct 18, 2007
  65. Linus TorvaldsOct 18, 2007
  66. Jeff KingOct 18, 2007
  67. david@lang.hmOct 18, 2007
  68. Jeff KingOct 18, 2007
  69. Linus TorvaldsOct 18, 2007
  70. Linus TorvaldsOct 18, 2007
  71. Linus TorvaldsOct 18, 2007
  72. Jeff KingOct 18, 2007
  73. Add a message explaining that automatic GC is about to startkoreth@midwinter.com, Oct 18, 2007
  74. Steven GrimmOct 18, 2007
  75. Jeff KingOct 18, 2007
  76. Shawn O. PearceOct 18, 2007
  77. Brian GernhardtOct 18, 2007
  78. Steven GrimmOct 18, 2007
  79. Jeff KingOct 18, 2007
  80. Shawn O. PearceOct 19, 2007
  81. git-gc: improve wording of --auto notificationJeff King, Oct 19, 2007
  82. Shawn O. PearceOct 19, 2007
  83. Jeff KingOct 19, 2007
  84. Nicolas PitreOct 18, 2007
  85. Nicolas PitreOct 18, 2007
  86. Jeff KingOct 18, 2007
  87. Jeff KingOct 18, 2007
  88. David KastrupOct 17, 2007
  89. Nicolas PitreOct 17, 2007
  90. David KastrupOct 17, 2007
  91. SeanOct 17, 2007
  92. David KastrupOct 17, 2007
  93. Sam RavnborgOct 16, 2007
  94. Paul WankadiaOct 18, 2007
  95. Linus TorvaldsOct 18, 2007
  96. Dmitry PotapovOct 18, 2007
  97. Andreas EricssonOct 16, 2007
  98. Jan-Benedict GlawOct 16, 2007
  99. Andreas EricssonOct 16, 2007
  100. Robin RosenbergOct 20, 2007

Read the whole thread, see it on lore, or plain text.

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