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Comment: from mpm on mercurial-devel
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Editor: abuehl
Comment: recat and style fixes
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== Basic Do's and Don'ts == == Basic do's and don'ts ==
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== Status and Error Messages == == Status and error messages ==
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CategoryContributing CategoryDeveloper

Basic do's and don'ts


  • don't use tabs
  • don't use lines longer than 80 characters
  • don't leave trailing whitespace
  • don't name functions or classes with Uppercase, CamelCase or lots_of_under_bars

  • don't make helper functions prefixed with do_
  • don't use underscores in identifiers in new code
  • in general, don't make mpm use his shift key any more than he has to

  • don't use default arguments without a good reason
  • don't use a class unless it makes your code smaller and easier to read
  • don't use Unicode strings unless you really grok Mercurial's charset philosophy

  • don't put OS-specific hacks outside of util.py and friends
  • don't use Python features from 2.5 or later (so no conditional expressions, unified try/except/finally)


  • use single quotes rather than double quotes
  • use a single underscore prefix for private methods and functions
  • use a single underscore prefix for a helper function
  • add a linebreak after a colon
  • add docstrings
  • use _() to mark things for i18n
  • add testcases to the test suite
  • run the test suite

-- mpm

Rules for tabs and spaces in C

See http://selenic.com/pipermail/mercurial-devel/2009-August/015110.html


The source includes a helper script, contrib/check-code.py, to check code for 'style errors'.

Variable conventions

Throughout the code, the following variables usually refer to the same thing:




a context.filectx instance

fn, fname



a python file(like) object

Status and error messages

Short messages should look like this:

adding foo.txt

Note the following:

  • it starts with a lower-case word.

  • it has no trailing full-stop (.).

Some existing strings don't follow this style and are kept like that for backwards compatibility reasons. But please write all new strings in this style.

The above message should look like this in your code:

ui.status(_('adding %s\n') % filename)

Please note:

  • The _ function is used to mark the string as translatable. Import it from the i18n module.

  • The string interpolation is done after the call to the _ function.


CodingStyle (last edited 2022-02-21 17:44:01 by RaphaelGomes)