You know you're a Perl programmer when...

You know you're a Perl programmer (or a CPAN author) when...

When you're thinking of packaging every piece of code as a CPAN module.

A couple of days ago I need a subroutine that takes a nested data structure (e.g. {vol1 => {a=>{b=>{c=>10}}}, vol2 => {a2=>{b2=>{c2=>20}}}}), a Unix-like path string (e.g. "vol1:/a/b/c") and return the branch/leaf node of the data structure according to the specified path (in this example, 10).

After browsing CPAN and a few minutes of reading the POD of some modules and not finding exactly what I wanted [*], that subroutine idea quickly transformed into an idea of a full-fledged CPAN module. The next day I uploaded Data::Filesystem to CPAN, which is actually yet another Data::Walker- / Data::Path- / Data::DPath-like module.

Turns out that I really don't need that module (yet, maybe someday). What I needed is just a simple Perl subroutine, and nothing more, because I will need to create a Javascript and PHP equivalent for it. Porting a whole module is not something I even want to do.

I wonder just how many CPAN authors that (do not) start their modules this way: overengineering of a small problem after not finding exactly what they want in CPAN.

[*] Btw, not finding what you want in one of the millions of CPAN modules has got to be one of the saddest thing in the universe. :-)

Yada Yada, Buat apa ?

Perl 5.12.0 baru saja keluar dan salah satu yang baru yaitu Yada Yada Operator.

Saya hanya bingung kapan atau situasi seperti apa yang membuat yada yada operator bisa (dan bagus) untuk digunakan ?,
Selintas saya teringat seperti pending nya RSpec.

Tip sprintf()

Salah satu fitur sprintf() (dan printf()) yang agak jarang diketahui/dipakai orang adalah bahwa sprintf() mendukung spesifikasi posisi argumen di dalam string formatnya, menggunakan prefiks NOMOR + "$":

% perl -E'say sprintf(q[%d %d %d], 1, 2, 3)'
1 2 3

% perl -E'say sprintf(q[%2$d %3$d %1$d], 1, 2, 3)'
2 3 1

Sayangnya, sprintf() tidak mendukung binding berdasarkan nama, seperti di Python:

print 'This {food} is {adjective}.'.format(adjective='absolutely horrible', food='spam')
This spam is absolutely horrible.

Kadang-kadang binding berdasarkan nama lebih nyaman, karena jika terjadi penambahan/pengurangan argumen, kita tidak harus menggeser-geser posisi lagi. Beberapa aplikasi tertentu seperti translasi juga kadang bisa dibuat lebih enak interfacenya seandainya menggunakan binding berbasis nama.

Jadi, bagaimana solusinya di Perl? Bisa dengan modul seperti String::Formatter, atau membuat sendiri :-) (seperti yang saya lakukan baru-baru ini di Data::Schema):

# $extra = {mverb => "harus"}; # mverb juga bisa 'sebaiknya'
# $args = [1, 10];
print stringf("Data %(mverb)s di antara %(0)d sampai %(1)d", $args, $extra);
Data harus lebih kecil di antara 1 sampai 10.

Fungsi stringf() mencoba mencari nilai binding di argumen kedua dst. Argumen dapat berupa hashref maupun arrayref, jadi saya bisa menggunakan binding berdasarkan posisi maupun nama. Nyaman :-)

Data::Dumper (Unfortunately, Part 2)

One of the first things a Perl programmer will notice when learning about Data::Dumper is: how weird and "inside out" the OO interface is. This is, I think, another unfortunate accident in the Perl history, as Data::Dumper, being the first of such modules, gets into the core in early Perl 5 and remains popular up until this day. But the interface and default settings apparently annoy a lot of people so much that alternatives and wrappers like Data::Dump, Data::Dumper::Again, Data::Dumper::Concise, among others, sprung up to life.

A loose analogy would be CVS which was popular for (too long) a time, and following it the explosion of alternative version control systems. Eventually after this phase a winner will emerge or dominate. In the version control system case it appears to be git. And in the Perl case I think it will be a builtin perl() method/function, like in Perl 6. Probably in 5.14? 5.16? 5.18? Don't you think it's about time Perl can "natively" dump its own structures in Perl, just like Python, Ruby, PHP, etc have been able to for a long time?

(Btw, lest anyone thinks otherwise: I do love DD. It has lots of options and has served its purpose well over the years.)

List::Util, List::MoreUtils, Util::Any (Unfortunately, Part 1)

The dichotomy of List::Util and List::MoreUtils is one of the unfortunate annoyances in Perl. One is without s, one is with s. Which function belongs to which? And no, you can't simply say, "f*ck it, just import everything!" as List::Util doesn't provide the usual ":all" import tag (RT).

Some thoughts (from someone who is largely ignorant on the history of both modules), all IMO:

1. Since List::Util is basically a convenient library, convenience should've been its main design goal. It should've been inclusive enough. The decision to deny the inclusion of any(), all(), none() just because they are too "trivial" to implement in one line of Perl was a bit strange, since max(), min(), etc are also trivial to implement in Perl.

2. List::MoreUtils should've included all the functionalities of List::Util, so one can use it *instead of* List::Util.

But hey, what happened happened.

Btw, we also have Perl 6's junction taking the "all", "any", "none" keyword.

And we'll see whether solutions like Util::Any will catch on, as it's another syntax to learn, another module to download and install. As with many annoyances, they are actually not that big of a deal. One can just spend a few seconds looking up the documentation to find the functions he/she wants, and after about tens of uses should remember which ones are in which.

Just when I'm warming to 5.10, comes 5.12!

Perl is far from dead/dying nowadays, with 5.12 being released recently, and the yearly timed-based release plan and all. In fact, just after I start to be comfortable using some of the 5.10 niceties, here comes a whole new version with even more niceties waiting to be explored!

Features in 5.10 I'm using regularly.

Defined-or (if there's only one feature I can have in 5.10, I pick this one).

State variables (love it!).

Features in 5.10 I'm starting to use.

-E switch (but my reflex still says -e all the time).

Recursive pattern in regex (e.g., via Regexp::Grammars).

say() (maybe if I say it often enough I'll start to say say more).

Features in 5.10 I rarely/ever touch.

Smart match (I know it's a godsend, but strangely I never feel the need for it so far).

given/when (I'm sticking with if/elsif/else, especially since given/when cannot be used as an expression yet).

Named capture in regex (yeah, old habits die hard).

5.10 and 5.12. IMO, 5.10 contains more "significant" visible new features for end users (i.e. Perl programmers), especially in the area of new syntax addition. It's 5 years in the making and delivers many features borrowed from Perl 6. But that is not meant to belittle 5.12 which also packs some major goodies, especially pluggable keywords. This one promises to usher us into a world of new syntaxes and mini languages, though it also confirms Perl as being a language that is "impossible to parse" and it surely will pose a challenge/headache for PPI and syntax highlight/Intellisense writers. I look forward to something like a better embedded SQL and templates (using pluggable keywords instead of treating everything as strings all the time).

Data::Dump::PHP

I actually don't believe there isn't something like this in CPAN yet. Well, actually there is PHP::Var, but it has bugs, doesn't handle scalars, and doesn't do recursive structure. But then I am equally surprised to be able to hack Data::Dump::PHP in just a couple of hours, by blatanly copying from Gisle Aas' Data::Dump and just modifying only what's necessary.

And another note, PHP's var_export() currently can't dump recursive structures, which Data::Dump::PHP can.