[Koha-devel] perltidy

[Colin Campbell]

There was a little bit of discussion on irc a few days back about 
perltidy and using it to get a bit of consistency in the formatting of 
the codebase. (consistency is good it means the surproses are more 
likely to be good than unpleasant).

For those of you unfamiliar with perltidy its the program in the perl 
module Perl::Tidy which if you run it on a perl script produces a 
version consistently formatted according to irs rules. For more info see 
the docs at http://perltidy.sourceforge.net
also man perltidy and perldoc Perl::Tidy

The default rules in perltidy are an expansion of those in the perl 
style guide
(perldoc perlstyle). Koha has its own set of recommendations, for the 
most part these are the defaults with perltidy. The uncommented lines in 
xt/perltidyrc show where we've overridden the defaults, they are:
cuddled_else
opening-brace-always-on-tight (a logical extension of cuddling your else)
paren-tightness=1 (uncommented as if a non-default but is the perltidy 
default)
vertical-tightness ( see the examples in Perl Best Practices for a 
reason for this)
maximum-line-length=178

I would suggest that the maximum-line-length be reduced ( The default 
value is 80), my reasoning is this: although we all have editors and 
terminals that handle long lines, we actually like to use that screen 
estate to see more than one file, so that letting the code wander off to 
the right makes it easier to miss important clues when reading it. 
Especially when using tools like vimdiff, git diff, git blame etc. I 
feel if you have a line like:
($lots, $of, $returns) = call_subroutine( $with, $more, $arguments, 
$than, $it $should @have) if ($i_want_to_hide_my_conditional && $x == $y);
a few judiciously placed new lines make it more readable and more 
maintainable, and with a long line length they disappear.

Also a quick unscientific scan through the existing codebase a few days 
back revealed 96.96% of existing lines are 80 characters or less ( 99.7% 
are less than 100) so that perltidying with a long line length may have 
a detrimental effect in some cases. Also it seems we are by default 
using shorter lines.

I think we should resolve this before considering any cleanup operations.

Finally a tip. I found this in the book Perl Hacks with these two vim 
mappings:
map ,pt <ESC>:%! perltidy<CR>
map ,ptv <ESC>: '<,'>! perltidy<CR>

I can use the commands ,pt and ,ptv in vim tp perltidy the file, or a 
region of the file within the editor. The latter is esprcially handy if 
I've added a few lines to a file and I want them formatted consistently 
but I don't want to obscure the files revision history by cleaning up 
code I've not touched.

Colin




-- 
Colin Campbell
Chief Software Engineer,
PTFS Europe Limited
Content Management and Library Solutions
+44 (0) 208 366 1295 (phone)
+44 (0) 7759 633626  (mobile)
colin.campbell at ptfs-europe.com
skype: colin_campbell2

http://www.ptfs-europe.com