I recently discovered YAML and thought it was very cool, so I've been anxiously awaiting a chance to actually use it. Well, I just started a new project and I thought YAML would be perfect for loading the config file.

I immediately had problems, because the YAML parser was unable to read in my config file. It gave me an error saying 'stream does not end with newline' - which left me perplexed because the file did, indeed, have a newline!

Since the problem seemed to be with the YAML syntax, I thought it would be clever to make Perl generate the file for me. I hardcoded a data structure in Perl and wrote out YAML using the Dump() command:

# yam1.pl
use strict;
use warnings;

use YAML;

my $config = {
  NAME => 'John Doe',
  ADDRESS => '123 Main St.',
  PHONE => {
    'Home' => '123-4444',
    'Work' => '123-5555',
  },
  CONTACTS => [
    'John',
    'Paul',
    'George',
  ],
};

print Dump( $config ), "\n";
[download]

I saved the output as config.yml, which looks like this:

---
ADDRESS: 123 Main St.
CONTACTS:
  - John
  - Paul
  - George
NAME: John Doe
PHONE:
  Home: 123-4444
  Work: 123-5555
[download]

This looked pretty much like what I already had, and sure enough, when I tried reading it back in, I again got the same error as before. This is what my reader script looked like:

# yam2.pl -- does NOT work!
use strict;
use warnings;

use YAML;
use Data::Dumper;

# load YAML file into perl hash ref?
my $config = Load("config.yml");
print Dumper($config), "\n";
[download]

I am too ashamed to admit on this board how long it took me to figure out the problem here, but I DID read the docs on cpan, search on google, search here, and search on the official yaml site, to no avail.

Here's the solution - which I'm posting here on the off chance that someone, some where, some day, may have the same bad fortune that I did, and will find this helpful.

# yam3.pl - Works! Yippie!
use strict;
use warnings;

use YAML;
use Data::Dumper;

# step 1: open file
open my $fh, '<', 'config.yml' 
  or die "can't open config file: $!";

# step 2: slurp file contents
my $yml = do { local $/; <$fh> };

# step 3: convert YAML 'stream' to perl hash ref
my $config = Load($yml);
print Dumper($config), "\n";
[download]

And there you have it: the Load function does not load a FILE, it loads a STREAM. Okay - so now I feel like an idiot. But I went back and read the documentation again, and this really is not that obvious. An example would have helped a bunch. There wasn't one there, but now there's one here.

Update:

After going back and very carefully reading the docs a third time (after bossman's replay) I finally found what I was really looking for all along - the LoadFile function:

# yam4.pl - Works also! Yippie!
use strict;
use warnings;

use YAML;
use Data::Dumper;

# step 1: open file
open my $fh, '<', 'config.yml' 
  or die "can't open config file: $!";

# step 2: convert YAML file to perl hash ref
my $config = LoadFile($fh);
print Dumper($config), "\n";
[download]

'You're Welcome' in advance...

---

---

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Titles consisting of a single word are discouraged, and in most cases are disallowed outright.

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)

	For:		Use:
	&		&
	<		&lt;
	>		&gt;
	[		&#91;
	]		&#93;

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.