On Thu, Sep 16, 2010 at 3:36 PM, Luke Kanies <[email protected]> wrote:
> On Sep 16, 2010, at 12:45 PM, Paul Berry wrote:
>
> I'm trying to get a better understanding of how variable scoping is
> intended to work in Puppet. Based on my reading of the code (and some
> experiments), here's the behaviors that I think are intended:
> 1. Variables defined at toplevel can be seen inside classes. For example:
> $var = "value"
> class foo { notify { $var: } }
> include foo
>
> This is a good idea and should stay, short and long term.
Agreed.
Also, please keep in mind this entire discussion applies to resource
defaults as well. Whatever behavior we implement for variables should
also be implemented for resource defaults.
> 2. Variables defined in a class can be seen inside the classes that it
> includes (this is really a generalization of (1)). Some might call
> this "dynamic scoping". For example:
> class foo {
> $var = "value"
> include bar
> }
> class bar { notify { $var: } }
> include foo
>
> From this on down, we're basically dealing with dynamic scoping, and in
> general, I think it should be fixed, and by fixed, I essentially mean
> removed.
Yes, I think this behavior should be completely eliminated. Many new
people are extremely surprised by this behavior when the first learn
of it.
It also causes many, many problems and provides little benefit in my experience.
If a class includes another class and the child needs access to a
variable in the default, if we must allow this behavior, we could do
it with namespace notation rather than scoping.
--
Jeff McCune
http://www.puppetlabs.com/
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