[chef] Re: new_resource ref

[Daniel DeLeo < >]

On Tuesday, July 1, 2014 at 8:39 AM, 

 
 wrote:

> I'm creating an lwrp and in the provider i'm creating a template. inside the
> template block @new_resource returns nil but new_resource gets a ref. 
> outside
> the block either works. why?  
>  
> I want to get a better understanding of what is going on.  
The blocks you pass to a resource declaration are evaluated using 
`instance_eval`, which changes the context in which the code is evaluated to 
be “inside” the resource object. In the normal recipe case, you have:

# `self` here is a Chef::Recipe object
template(“name”) do
  # `self` here is a Chef::Resource::Template object
end

To make this a little nicer in the LWRP case, resources in LWRPs have a 
reference to their parent object (your provider class) and they forward any 
unknown methods (in your case `new_resource`) to the parent.

This is a pretty in-depth explanation of how ‘self’ in ruby gets manipulated 
by various kinds of `eval`, if you want to learn more: 
http://yehudakatz.com/2009/11/15/metaprogramming-in-ruby-its-all-about-the-self/

HTH,

--  
Daniel DeLeo