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These rules are fairly standard and boring. People will bitch about something
in here, no doubt. Get over it. Much of this was stolen from the Linux Kernel
coding style, because most of it makes good sense. If you disagree, that's OK,
but please stick to the rules anyway ;-)
Language
Please use Python where possible. It's not the ideal language for everything,
but it's pretty good, and consistency goes a long way in making the project
maintainable. (Obviously using C or whatever for writing tests is fine).
Indentation & whitespace
Format your code for an 80 character wide screen.
Indentation is hard tabs, equivalent to 8 spaces. Yes, I know that's pretty
large, but especially in Python where code flow is controlled by indentation
levels, it's critical for it to be clearly visibile.
People will claim that doesn't allow them enough levels of indentation on an
80 character screen - they need to fix their code instead: use smaller
functions, and more local variables - it makes the code so much easier to read.
Don't leave trailing whitespace, or put whitespace on blank lines.
Leave TWO blank lines between functions - this is Python, there are no clear
function end markers, and we need help.
Variable names and UpPeR cAsE
Use descriptive variable names where possible - it helps to make the code
self documenting.
Don't use CamelCaps style in most places - use underscores to separate parts
of your variable_names please. I shall make a bedgrudging exception for class
names I suppose, but I'll still whine about it a lot.
Comments
Generally, you want your comments to tell WHAT your code does, not HOW.
We can figure out how from the code itself (or if not, your code needs fixing).
Try to describle the intent of a function and what it does in a triple-quoted
(multiline) string just after the def line. We've tried to do that in most
places, though undoubtedly we're not perfect. A high level overview is
incredibly helpful in understanding code.
Simple code
Keep it simple; this is not the right place to show how smart you are. We
have plenty of system failures to deal with without having to spend ages
figuring out your code, thanks ;-) Readbility, readability, readability.
I really don't care if other things are more compact.
"Debugging is twice as hard as writing the code in the first place. Therefore,
if you write the code as cleverly as possible, you are, by definition, not
smart enough to debug it." Brian Kernighan
Function length
Please keep functions short, under 30 lines or so if possible. Even though
you are amazingly clever, and can cope with it, the rest of us are all stupid,
so be nice and help us out. To quote the Linux Kernel coding style:
Functions should be short and sweet, and do just one thing. They should
fit on one or two screenfuls of text (the ISO/ANSI screen size is 80x24,
as we all know), and do one thing and do that well.
Exceptions
When raising exceptions, the preferred syntax for it is:
raise FooException('Exception Message')
Please don't raise string exceptions, as they're deprecated and will be removed
from future versions of python. If you're in doubt about what type of exception
you will raise, please look at http://docs.python.org/lib/module-exceptions.html
and client/common_lib/error.py, the former is a list of python built in
exceptions and the later is a list of autotest/autoserv internal exceptions. Of
course, if you really need to, you can extend the exception definitions on
client/common_lib/error.py.
Submitting patches
Generate universal diffs. Email them to autotest@test.kernel.org.
Most mailers now break lines and/or changes tabs to spaces. If you know how
to avoid that - great, put your patches inline. If you're not sure, just
attatch them, I don't care much. Please base them off the current version.
Don't worry about submitting patches to a public list - everybody makes
mistakes, especially me ... so get over it and don't worry about it.
(though do give your changes a test first ;-))
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