Not sure if it is what you specifically want, but you could check out perltidy. It cleans up source code pretty good and is configurable.

#! perl -sw
use strict;
use List::Util qw[ max ];

my $first = <>;
my @ugly = <>;
my $last = pop @ugly;

my @bits = map[ m[(^\s+)(\S+)\s*=>\s*(\S+),\n] ], @ugly;
my $largest = max( map{ length( $_->[1] ) } @bits );

print $first;
printf "%s%-${largest}s => %s,\n", @$_ for @bits;
print $last;
[download]

Output:

C:\test>1159396
C:\test>1159396
%some_hash = (
               key => "value1",
               larger_key => "value2",
               even_larger_key => "value3",
             );
^Z
%some_hash = (
               key             => "value1",
               larger_key      => "value2",
               even_larger_key => "value3",
             );
[download]

What a pity! In Emacs, you can use align-regex , which I usually bind to C-x l . I can then just select the region and press C-x l => Enter and voilą!

($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,
[download]

I normally move the cursor to the last => and type M-x align-current .

One day I'll automatise it to happen with each auto indent. ..

FWIW I seem to remember that perltidy can't do this.

Cheers Rolf
_{(addicted to the Perl Programming Language and ☆☆☆☆ :)
Je suis Charlie!}

It aligns the assignment symbol = for me, too, which I don't want. Do you have any special align-rules-alist to prevent that?

#                     here,  instead of here
#                      v           V
my %periods            =  (Mercury => { orbital => 0.24,  rotation => 
+58.64 },
               Venus   => { orbital => 0.62,  rotation => -243.02 },
               Earth   => { orbital => 1.00,  rotation => 1.00 },
               Mars    => { orbital => 1.88,  rotation => 1.03 },
               Jupiter => { orbital => 11.86, rotation => 0.41 },
               Saturn  => { orbital => 29.46, rotation => 0.43 },
               Uranus  => { orbital => 84.01, rotation => -0.72 },
               Neptune => { orbital => 164.8, rotation => 0.67 },
              );
[download]

Moving the structure from the assignment line doesn't help:

my %periods            =  (
               Mercury => { orbital => 0.24,  rotation => 58.64 },
               Venus   => { orbital => 0.62,  rotation => -243.02 },
# ...
[download]

($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,
[download]

> FWIW I seem to remember that perltidy can't do this.

wrong see http://perltidy.sourceforge.net/node005.html

I think I confused it with Data::Dump and Data::Dumper which do not align (fat) commas.

update

But I'm still not convinced about perltidy's performance for interactive use from within an IDE.

Cheers Rolf
_{(addicted to the Perl Programming Language and ☆☆☆☆ :)
Je suis Charlie!}

> In Emacs, you can use align-regex , which I usually bind to C-x l . I can then just select the region and press C-x l => Enter and voilą!

There is room for much improvement...

1. selecting the region:

a combination of backward-up-list and mark-sexp will select the surrounding structure (repeating will extend the selection till statement (ie. ';') boundary.

(please note that cperl-mode injects here some semantic knowledge about the code's structure which can't be reflected in a simple regexp rule)

2. the rule for align-current has the advantage to harmonize the surrounding whitespaces too. And align-regexp seems to allow the same extended logic.

So combining both steps bound to a key should make alignment of fat-commas quite easy.

I experimented with a kmacro and it seemed quite nice. :)

Cheers Rolf
_{(addicted to the Perl Programming Language and ☆☆☆☆ :)
Je suis Charlie!}

You could use Data::Dumper::Perltidy which uses a default perltidy config, but can be configured to use your own .perltidy.rc:

perl -MData::Dumper::Perltidy -E'
$href = { foo => "bar", longer => "baz", longest => "qux" };
say Dumper $href;
'
[download]

$VAR1 = {
    'foo'     => 'bar',
    'longer'  => 'baz',
    'longest' => 'qux'
};
[download]

Hope this helps!