I'm using DateTime objects a lot these days: anytime I get some date/time data from outside of Perl, the first thing I do is convert them to DateTime object, to avoid calculation/formatting hassle ahead.

However, the dumps are not pretty.

% perl -MDateTime -MData::Dump -e'dd [DateTime->now]'

[
  bless({
    formatter       => undef,                                         
    local_c         => {
                         day => 21,
                         day_of_quarter => 51,
                         day_of_week => 5,
                         day_of_year => 141,
                         hour => 8,
                         minute => 55,
                         month => 5,
                         quarter => 2,
                         second => 36,
                         year => 2010,
                       },
    local_rd_days   => 733913,
    local_rd_secs   => 32136,
    locale          => bless({
                         "default_date_format_length" => "medium",
                         "default_time_format_length" => "medium",
                         en_complete_name => "English United States",
                         en_language => "English",
                         en_territory => "United States",
                         id => "en_US",
                         native_complete_name => "English United States",
                         native_language => "English",
                         native_territory => "United States",
                       }, "DateTime::Locale::en_US"),
    offset_modifier => 0,
    rd_nanosecs     => 0,
    tz              => bless({ name => "UTC" }, "DateTime::TimeZone::UTC"),
    utc_rd_days     => 733913,
    utc_rd_secs     => 32136,
    utc_year        => 2011,
  }, "DateTime"),
]

$ perl -Ilib -MDateTime -MData::Dump -e'$Data::Dump::CUSTOM_CLASS_DUMPERS{"DateTime"} = sub { "$_[0]" }; dd [DateTime->now]'
[2010-05-21T08:57:45]

or:

$ perl -Ilib -MDateTime -MData::Dump -e'package DateTime; sub dump { "$_[0]" }; package main; dd [DateTime->now]'
[2010-05-21T08:58:09]

I know some other dumper in CPAN probably has this ability, but I like Data::Dump's output.

If you want to take a look at a couple of small patches to Data::Dump: http://github.com/sharyanto/data-dump

I know I made a mistake by doing a double glob, but why this pattern of output? Note, there is only one file matching /etc/magic.* and two files matching /etc/magic*, and none matching /etc/magic.dragon*

% perl -E'say (glob </etc/magic.*>) for 1..10'
/etc/magic.mime
2
/etc/magic.mime
4
/etc/magic.mime
6
/etc/magic.mime
8
/etc/magic.mime
10

% perl -E'say (glob </etc/magic*>) for 1..10'
/etc/magic
/etc/magic.mime
3
/etc/magic
/etc/magic.mime
6
/etc/magic
/etc/m…

Everytime I browse through CPAN recent uploads, and see versions of modules with RJBS's automatic numbering scheme, like 2.100920 or 1.091200 I tend to read it as 2.(noise) and 1.(more noise).

The problem is that it doesn't look like a date at all (is there any country or region using day of year in their date??). I've never been bothered enough with this though, as I don't use this scheme myself, but have always had a suspicion that this obfuscation is deliberate for some deep reason.

Turns out that it's ="ht…

perlmv is a script which I have personally been using all the time for years, but has only been uploaded to CPAN today. The concept is very simple, to rename files by manipulating $_ in specified Perl code. For example, to rename all .avi files to lowercase,

$ perlmv -de '$_=lc' *.avi

The -d option is for dry-run, so that we can test our code before actually renaming the files. If you are sure that the code is correct, remove the -d (or replace it with -v, for verbose).

p…

Spent 10 minutes the other day scratching my head after my Perl code stopped working following a single added line (can you guess which one?):

LABEL1:
my @var;
for (...) {
next LABEL1;
}

The error message is "Label not found for 'next LABEL1'. I think Perl could be better at handling this kind of mistake.

The style of returning different things in list vs scalar context has been debated for a long time (for a particular example, this thread in Perlmonks).

A few months ago I made a decision that all API functions in one of my projects should return this:

return wantarray ? ($status, $errmsg, $result) : $result;

That is, we can skip error checking when we don't want to do it.

Now, in the spirit of Fatal and autodie, I am changing the above…