From: Dave Thomas <dave@...>
Date: 2008-03-17T00:59:43+09:00
Subject: Re: argh! more undocumented mysteries: to_yaml


On Mar 16, 2008, at 8:56 AM, Tom Cloyd wrote:

> I'm exploring the wonders of the Object class, and I see  
> Object#to_yaml. Seems pretty obvious what to expect here, which  
> would seem to account for the total lack of documentation in each of  
> the gazillion instances of this method which appear in core library.  
> Still, let's test it...
>
> irb(main):010:0> [2,5,3,6,'abc'].to_yaml
> NoMethodError: undefined method `to_yaml' for [2, 5, 3, 6,  
> "abc"]:Array
>       from (irb):10
>       from :0
>
> Can someone explain what just happened?


Tom:

Could you tell us just where you found the description of  
Object#to_yaml.

As others have explained, to_yaml is not a built-in method. It is  
added when you require the yaml library. So, if a piece of  
documentation is out there that fails to make it clear that this  
library must be loaded before to_yaml is called, then that  
documentation needs to be fixed.

As others have also pointed out, once the library is loaded, you can  
indeed invoke to_yaml on arrays, hashes, and so on.


Regards


Dave Thomas