I hate Perl. Hate it, hate it, hate it...

[jducoeur]

Okay, all of you Perl aficionados who keep telling me what a nice language it is. I have a question for you. I'm trying to write a dirt-simple program to parse an input form using the standard CGI library on Unix. My code looks something like this:


use CGI qw(:standard) ;

$query = new CGI;

my $age = $query->param('age');
my $params = $query->Vars;
my $age2 = $params->{'age'};
print $query->Dump();


Why, prithee tell, do the first two versions (both taken directly from the CGI documentation) keep insisting that $age and $age2 are empty strings, despite the dump quite happily showing that the age parameter is being passed in as expected? This damned language is so opaque (and the documentation so miserable) I'm at a dead end even trying to figure out where the data is hiding...

Comments

[tangerinpenguin.livejournal.com]

This is just speculation since I don't use that particular library much, but since you're using the object-oriented API rather than the functional shorthand, have you tried leaving off the :standard keyword to the use declaration?

[jducoeur]

Tried that after you suggested it, but that turned out not to be it. (Fortunately, since I was actually using a mix of the OO and functional versions.) Thanks for the idea, though...

show your form please

[livemerlyn.livejournal.com]

Without the whole picture, we'd only be guessing.

[crschmidt.livejournal.com]

So, I have this:

#!/usr/bin/perl

use CGI qw(:standard);
$q = new CGI;
print "Content-Type: text/plain\r\n\r\n"; 

print $q->param('age');

then:
http://crschmidt.net/code.cgi?age=1

works.

So, it sounds like your setup might be broken?

[jducoeur]

As it happens, it was -- the form was subtly broken. I eventually managed to track that down, but it leaves a very different question mystifying me: why the heck does $query->Dump() manage to show the fields parsed out perfectly fine (including the broken ones), while the individual $query->param() calls fail to do so? There's something very weird going on in that library -- either the internal data structures aren't consistent, or there's a subtlety I'm missing...

[crschmidt.livejournal.com]

Hard to know without seeing how your form was broken, and what the HTML behind the Dump was producing. (For example, an extra < in a variable might not be obvious in an HTML form, because it gets eaten by something, or something of that nature.)

In any case, sounds like you got it sorted.

[mneme]

Depends on what was going on -- was it mixing get and post, frex? CGI.pm will happily parse both get and post -- but on a post request, it will only make the post options available -- the query string options (if also existent -- usually because they're in the form action) will be parsed but not made accessable unless requested. Not sure what else would generate the behavior described.

Perl is actually a remarkably elegant language -- for one that's as big as it is. (that said, there's a lot of accumulated cruft, some of which isn't really as useful as originally intended -- like the mutating funny characters on the beginnings of variables, and the related differences in the syntax for accessing a thing and for accessing a reference to the very same thing. Much of this will change in perl 6).

But CGI.pm is a bloated and over-ambitious tool, and one I'd not normally recommend using -- you're better off using a smaller CGI library that doesn't try to also handle HTML creation -- or just jump to mod perl, depending on your platform.

[jducoeur]

Hmm. The mod perl point is well-taken. I don't run the site (it's my public site, from a Big Commercial ISP), so I honestly don't know whether mod perl is a practical option, but it wouldn't surprise me if it is. (I haven't managed to convince them to bring Ruby up yet, but they do grasp that decent perl support is important.) Heaven knows, some of my apps would probably be happier in a mod perl environment.

Setting that aside, though: do you have recommendations for a CGI library? Everything I'd seen has tended to indicate that CGI.pm is The Library You're Supposed to Use for the purpose, but I agree that it's total overkill for my purposes, and I'm happy to consider something more concise. (Although, that said, I don't know how much flexibility I have in pulling new modules onto my system -- see previous comment about Big Commercial ISP...)

[mneme]

CGI::Lite is much better. You might also want to try out CGI::Minimal, which looks pretty good on a first blush.

[jducoeur]

Cool -- thanks!