Hi John,
I think the behavior you discovered is a natural and expected consequence
> of Puppet's name scoping and resolution rules. The current namespace is
> searched first for unqualified class names. Only if no matching class is
> found there will other namespaces be considered.
>
> The difference between the behavior with parametrized-class syntax and
> 'include' for declaring the tomcat class is also normal. It turned out
> well in your case by alerting you to the problem, but usually it is a
> problem that you need to work around. It is only a bug to declare a class
> multiple times when the second or some later declaration is made in the
> parametrized style, and then only because of the possibility of
> inconsistent parametrization. You can 'include' a class as many times as
> you want.
>
I understand the difference between the parameterized style and the include
syntax. That is something that is explained thoroughly in the documentation.
> Finally, although it is usually unnecessary to use absolute class names
> (e.g. "::tomcat") to declare classes, that's because name clashes are
> fairly rare. Although you found Puppet's behavior surprising, I wouldn't
> call it buggy.
>
What I found surprising, was the fact that the "include tomcat" or "class {
'tomcat': }" syntax is documented everywhere as the declaration of the main
class of a module, without any mention of it possibly being "overridden" by
this kind of namespace clash. For variables it seems to be well documented
that we should use namespacing and top-scoping to avoid these clashes.
I used a similar setup to what is described by Craig Dunn (now a Puppetlabs
employee) at http://www.craigdunn.org/2012/05/239/, which happens to have
the exact same invocation as I did:
class profile::tomcat {
class { "jdk": }
class { "tomcat": }
}
As this is a blog post, it probably wasn't tested, but it shows there are
others who find this kind of invocation intuitive.
While it is easy to work around this by top-scoping the class, some form of
documented warning might prevent some hairpulling :)
Kind regards,
k
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