Re: Code guidelines and bash

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Re: Code guidelines and bash

Chris Douglas
[moving to common-dev@]

The 80 character limit is for legibility across dev environments. If
it's impeding that goal in bash, then nobody will insist on it.

Since HADOOP-9902 rewrites most of this code, the particular cases can
be worked through in that JIRA. -C

On Sat, Jul 26, 2014 at 12:20 PM, Allen Wittenauer <[hidden email]> wrote:

> Hey folks:
>
>    Deep linked by http://wiki.apache.org/hadoop/CodeReviewChecklist is the
> rule  that line length should be ideally maximum 80 chars.  (Sun coding
> guidelines.)  In general, it's a good idea and it works for many many
> languages...
>
>    Now the caveat.
>
>    As most of you know, I've been hacking on HADOOP-9902 off and on for a
> year now.   [For those that don't, this is an almost complete rewrite of
> most of the major shell code that we ship with Hadoop.  The stuff that was
> missed I'll pick it up after this gets committed.]   As part of this, I
> recently reformatted the last patch to fit that 80 character requirement as
> best I could.  The result is... not good.  Not good at all.  In many ways,
> it actually hurt readability even beyond the lack of indentation that Bash
> Beautifier doesn't support for line continuation. (That case statement in
> bin/hadoop is painful to look at and makes me cry.)
>
>    Barring anymore feedback, it's pretty much ready to commit. But before
> that happens, do we want to specify that bash has different line length
> requirements?  Say 120 chars?  Most of the problems stem from our usage of
> REALLY LONG env var names that can't really be changed at this point
> without *massively* screwing backward compatibility. (Hello,
> YARN_RESOURCEMANAGER_OPTS... I'm talking about you!).
>
>   Bouncing the idea around a few folks, they all seem to agree that 80 is
> just too hard for bash given our general use case, but I think it'd be good
> to have something official.
>
> Thoughts?
>
> Thanks.
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Re: Code guidelines and bash

Doug Cutting
On Sun, Jul 27, 2014 at 9:28 PM, Ted Dunning <[hidden email]> wrote:
> I don't know of any dev environments in common use today that can't display >100 characters.

I edit in an 80-column Emacs window that just fits beside an 80-column
shell window on a portrait-rotated 24" monitor.

Doug
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Re: Code guidelines and bash

Andrew Purtell
On Mon, Jul 28, 2014 at 12:05 PM, Doug Cutting <[hidden email]> wrote:

> On Sun, Jul 27, 2014 at 9:28 PM, Ted Dunning <[hidden email]>
> wrote:
> > I don't know of any dev environments in common use today that can't
> display >100 characters.
>
> I edit in an 80-column Emacs window that just fits beside an 80-column
> shell window on a portrait-rotated 24" monitor.
>

​You win the Internet today, Old School category! (smile)​


--
Best regards,

   - Andy

Problems worthy of attack prove their worth by hitting back. - Piet Hein
(via Tom White)
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Re: Code guidelines and bash

俊平堵-2
Sun's java code convention (published in year of 97) suggest 80 column per
line for old-style terminals. It sounds pretty old, However, I saw some
developers (not me :)) like to open multiple terminals in one screen for
coding/debugging so 80-colum could be just fit. Google's java convention (
https://google-styleguide.googlecode.com/svn/trunk/javaguide.html#s4.4-column-limit)
shows some flexibility here with 80 or 100 column (and some exception
cases).
Like Chris mentioned early, I think this 80-column should just be a general
guideline but not a strict limit - we can break it if it hurts legibility
of code reading.
btw, some research work found that CPL (characters per line) only had small
effects on readability for news, including factors of speed and
comprehension (
http://psychology.wichita.edu/surl/usabilitynews/72/LineLength.asp). Not
sure if reading code is the same (assume break lines properly).


2014-07-29 15:24 GMT+08:00 Andrew Purtell <[hidden email]>:

> On Mon, Jul 28, 2014 at 12:05 PM, Doug Cutting <[hidden email]> wrote:
>
> > On Sun, Jul 27, 2014 at 9:28 PM, Ted Dunning <[hidden email]>
> > wrote:
> > > I don't know of any dev environments in common use today that can't
> > display >100 characters.
> >
> > I edit in an 80-column Emacs window that just fits beside an 80-column
> > shell window on a portrait-rotated 24" monitor.
> >
>
> ​You win the Internet today, Old School category! (smile)​
>
>
> --
> Best regards,
>
>    - Andy
>
> Problems worthy of attack prove their worth by hitting back. - Piet Hein
> (via Tom White)
>
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Re: Code guidelines and bash

Colin McCabe
On Tue, Jul 29, 2014 at 2:45 AM, 俊平堵 <[hidden email]> wrote:

> Sun's java code convention (published in year of 97) suggest 80 column per
> line for old-style terminals. It sounds pretty old, However, I saw some
> developers (not me :)) like to open multiple terminals in one screen for
> coding/debugging so 80-colum could be just fit. Google's java convention (
> https://google-styleguide.googlecode.com/svn/trunk/javaguide.html#s4.4-column-limit)
> shows some flexibility here with 80 or 100 column (and some exception
> cases).
> Like Chris mentioned early, I think this 80-column should just be a general
> guideline but not a strict limit - we can break it if it hurts legibility
> of code reading.
> btw, some research work found that CPL (characters per line) only had small
> effects on readability for news, including factors of speed and
> comprehension (
> http://psychology.wichita.edu/surl/usabilitynews/72/LineLength.asp). Not
> sure if reading code is the same (assume break lines properly).

There is a lot of contradictory research in this area.  For example,
http://eric.ed.gov/?id=EJ749012 talks about 70 characters per line as
"ideal."

I think a lot of these studies don't really translate very well to
code.  (A lot of them are college students seeing how quickly they can
read a news article.)  Code with extremely long line lengths tends to
have super-deep nesting, which makes it hard to keep track of what is
going on (the so-called "arrow anti-pattern").  This is especially
true when there are break and continue statements involved.
Super-long lines make diffs very difficult to do.  And it's just
unpleasant to read, forcing users to choose between horizontal
scrolling or tiny text...

Maybe it makes sense to extend the bash line length, though, if it's
tough to fit in 80 chars.  Bash is whitespace sensitive and doing the
line continuation thing is a pain.  Another option might be renaming
some variables, or using temp variables with shorter names...

best,
Colin


>
>
> 2014-07-29 15:24 GMT+08:00 Andrew Purtell <[hidden email]>:
>
>> On Mon, Jul 28, 2014 at 12:05 PM, Doug Cutting <[hidden email]> wrote:
>>
>> > On Sun, Jul 27, 2014 at 9:28 PM, Ted Dunning <[hidden email]>
>> > wrote:
>> > > I don't know of any dev environments in common use today that can't
>> > display >100 characters.
>> >
>> > I edit in an 80-column Emacs window that just fits beside an 80-column
>> > shell window on a portrait-rotated 24" monitor.
>> >
>>
>> You win the Internet today, Old School category! (smile)
>>
>>
>> --
>> Best regards,
>>
>>    - Andy
>>
>> Problems worthy of attack prove their worth by hitting back. - Piet Hein
>> (via Tom White)
>>
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Re: Code guidelines and bash

Steve Loughran-3
one argument in favour of 80 is that it's easier to side-by-side diff

even so, I find it restrictive in Java code; once you go for long env vars
in bash-land then you are in trouble. As for python, you have to indent
according to your code flow.

were we to have a special getout of 120 chars in .sh, .py, and other
scripts, I'd be happy.




On 29 July 2014 18:59, Colin McCabe <[hidden email]> wrote:

> On Tue, Jul 29, 2014 at 2:45 AM, 俊平堵 <[hidden email]> wrote:
> > Sun's java code convention (published in year of 97) suggest 80 column
> per
> > line for old-style terminals. It sounds pretty old, However, I saw some
> > developers (not me :)) like to open multiple terminals in one screen for
> > coding/debugging so 80-colum could be just fit. Google's java convention
> (
> >
> https://google-styleguide.googlecode.com/svn/trunk/javaguide.html#s4.4-column-limit
> )
> > shows some flexibility here with 80 or 100 column (and some exception
> > cases).
> > Like Chris mentioned early, I think this 80-column should just be a
> general
> > guideline but not a strict limit - we can break it if it hurts legibility
> > of code reading.
> > btw, some research work found that CPL (characters per line) only had
> small
> > effects on readability for news, including factors of speed and
> > comprehension (
> > http://psychology.wichita.edu/surl/usabilitynews/72/LineLength.asp). Not
> > sure if reading code is the same (assume break lines properly).
>
> There is a lot of contradictory research in this area.  For example,
> http://eric.ed.gov/?id=EJ749012 talks about 70 characters per line as
> "ideal."
>
> I think a lot of these studies don't really translate very well to
> code.  (A lot of them are college students seeing how quickly they can
> read a news article.)  Code with extremely long line lengths tends to
> have super-deep nesting, which makes it hard to keep track of what is
> going on (the so-called "arrow anti-pattern").  This is especially
> true when there are break and continue statements involved.
> Super-long lines make diffs very difficult to do.  And it's just
> unpleasant to read, forcing users to choose between horizontal
> scrolling or tiny text...
>
> Maybe it makes sense to extend the bash line length, though, if it's
> tough to fit in 80 chars.  Bash is whitespace sensitive and doing the
> line continuation thing is a pain.  Another option might be renaming
> some variables, or using temp variables with shorter names...
>
> best,
> Colin
>
>
> >
> >
> > 2014-07-29 15:24 GMT+08:00 Andrew Purtell <[hidden email]>:
> >
> >> On Mon, Jul 28, 2014 at 12:05 PM, Doug Cutting <[hidden email]>
> wrote:
> >>
> >> > On Sun, Jul 27, 2014 at 9:28 PM, Ted Dunning <[hidden email]>
> >> > wrote:
> >> > > I don't know of any dev environments in common use today that can't
> >> > display >100 characters.
> >> >
> >> > I edit in an 80-column Emacs window that just fits beside an 80-column
> >> > shell window on a portrait-rotated 24" monitor.
> >> >
> >>
> >> You win the Internet today, Old School category! (smile)
> >>
> >>
> >> --
> >> Best regards,
> >>
> >>    - Andy
> >>
> >> Problems worthy of attack prove their worth by hitting back. - Piet Hein
> >> (via Tom White)
> >>
>

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