[chef] Re: Passing blocks as LWRP attributes

[Daniel DeLeo < >]

On Tuesday, December 4, 2012 at 8:26 AM, Benton Roberts wrote:

Ohai, chefs!

I am trying to write a LWRP that "wraps" the Opscode deploy_revision Provider to add some organization-specific functionality. The LWRP sets some organization-wide defaults, defines some supporting Chef Resources, and then defines the usual Opscode deploy_revision Resource. Many of the attributes for my LWRP simply pass their values through to the deploy_revision Resource, exactly as one would expect:

deploy_revision app_name do

revision new_resource.revision

repository new_resource.repository

migration_command new_resource.migration_command

enable_submodules new_resource.enable_submodules

…[and so on]

This works fine for simple value attributes like those listed above, but does not seem to work for the block attributes: before_migrate, after_symlink, etc. Using the same syntax (a regular "do…end" statement passed as an argument to the LWRP's before_migrate method) just yields a value of nil for "new_resource.before_migrate".

Is there a way to pass blocks to an LWRP, and then pass them onto deploy_revision so that the blocks get invoked in the same context (i.e. "releases_dir")? How would you handle this situation?

Thanks in advance,

- benton

------------

Benton Roberts

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I'm guessing you need to "blockinate" your blocks, which means use code like this:

  before_migrate &new_resource.before_migrate # note the ampersand

This is because ruby treats blocks as both regular objects and also a special thing. This blog post may be of use:

http://yehudakatz.com/2010/02/25/rubys-implementation-does-not-define-its-semantics/

-- 

Daniel DeLeo