To_yaml method for array

This is irb.

irb
irb(main):001:0> a = %w[ 1 2 3 ]
=> [“1”, “2”, “3”]
irb(main):002:0> a.to_yaml
NoMethodError: undefined method `to_yaml’ for [“1”, “2”, “3”]:Array
from (irb):2

This is Rails script/console

a = %w[ 1 2 3]
=> [“1”, “2”, “3”]

a.to_yaml
=> “— \n- “1”\n- “2”\n- “3”\n”

However no where in ActiveSupport I can find where Rails is implementing
the method to_yaml.

I go to http://www.ruby-doc.org/core/ and look for Array methods. I see
to_yaml. So why in the irb I am getting undefined method to_yaml?

require ‘yaml’

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Raj S. wrote:

| However no where in ActiveSupport I can find where Rails is implementing
| the method to_yaml.
|
| I go to http://www.ruby-doc.org/core/ and look for Array methods. I see
| to_yaml. So why in the irb I am getting undefined method to_yaml?

require ‘yaml’

This adds the desired functionality. Alas, the RDoc generated
(currently) includes functions in Core lib that are actually part of
STDLIB.


Phillip G.
Twitter: twitter.com/cynicalryan
Blog: http://justarubyist.blogspot.com

A born loser:
~ Somebody who calls the number that’s scrawled in lipstick on the phone
~ booth wall-- and his wife answers.
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On Wed, May 21, 2008 at 7:37 PM, Raj S. [email protected] wrote:

I go to http://www.ruby-doc.org/core/ and look for Array methods. I see
to_yaml. So why in the irb I am getting undefined method to_yaml?

You need to

require ‘yaml’

to load the yaml library.

Regards,
Sean

On Wednesday 21 May 2008, Raj S. wrote:

However no where in ActiveSupport I can find where Rails is implementing
the method to_yaml.

I go to http://www.ruby-doc.org/core/ and look for Array methods. I see
to_yaml. So why in the irb I am getting undefined method to_yaml?

You need to require ‘yaml’ before using the Array#to_yaml method (or any
other
predefined to_yaml methods, for the matter). I guess Rails console
already
does that itself, so there your code works. Regarding the documentation,
unfortunately the one you mention mixes ‘core’ classes (that is, classes
and
modules which are always availlable) and ‘standard library’ classes
(classes
and modules which are distributed with ruby but need to be required to
be
used). The to_yaml method is defined in a file in the standard library,
but
that can’t be guessed from the documentation. If you want to generate
the
documentation for only the core classes, you can follow the procedure
explained in this thread:
http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/294786
The documentation for only the standard library can be downloaded here:
http://www.ruby-doc.org/stdlib/

I hope this helps

Stefano

On Wednesday 21 May 2008, James B. wrote:

I go to http://www.ruby-doc.org/core/ and look for Array methods. I see
to_yaml. So why in the irb I am getting undefined method to_yaml?

rdoc, run over the ruby source, is dopey in that it parses the yaml
files, sees that they modify core Ruby objects, then generates rdoc that
presents those core objects as if they had yaml methods built-in.

In actual practice, you have to explicitly mix-in yaml to get that
behavior.

Actually, you don’t need to mix-in yaml. When you require yaml.rb, it
will add
the generic to_yaml method to the Object class itself (or to the Kernel
module, I’m not sure) and the more specialized methods to those classes
for
which they exist (such as Array, String and Hash). There’s no mixing-in
involved, as far as I can tell.

Stefano

You followup-guys are overkilling on such a simple question with such a
simple solution… i am sure in some time there be dragons! :wink:

I go to http://www.ruby-doc.org/core/ and look for Array methods. I see
to_yaml. So why in the irb I am getting undefined method to_yaml?

rdoc, run over the ruby source, is dopey in that it parses the yaml
files, sees that they modify core Ruby objects, then generates rdoc that
presents those core objects as if they had yaml methods built-in.

In actual practice, you have to explicitly mix-in yaml to get that
behavior.


James B.

http://www.rubyaz.org - Hacking in the Desert
http://www.jamesbritt.com - Playing with Better Toys

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Marc H. wrote:
| You followup-guys are overkilling on such a simple question with such a
| simple solution… i am sure in some time there be dragons! :wink:

Though, if somebody uses a search engine, the chance of finding a
solution to the same problem by somebody else increases.

Also, explanations as to why something is not the way as it is
expected helps in troubleshooting problems of a similar nature. :wink:


Phillip G.
Twitter: twitter.com/cynicalryan
Blog: http://justarubyist.blogspot.com

ZEAL:
Quality seen in new graduates – if you’re quick.
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Stefano C. wrote:

Actually, you don’t need to mix-in yaml. When you require yaml.rb, it will add
the generic to_yaml method to the Object class itself (or to the Kernel
module, I’m not sure) and the more specialized methods to those classes for
which they exist (such as Array, String and Hash). There’s no mixing-in
involved, as far as I can tell.

Yes, you are quite right.


James B.

http://www.rubyaz.org - Hacking in the Desert
http://www.jamesbritt.com - Playing with Better Toys

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