On Friday, May 10, 2013 9:53:39 AM UTC-5, christian...@gmail.com wrote:
>
> Thx, maybe this was a little too straight from the hip... BTW: I've tried
> it - it even worked... but I see that's probably caused by a lot of strange
> luck...
>
>
>> Subclasses can never 'override' ancestor class variables. They can
>> partially *hide* them within their own scope by declaring a same-named
>> local variable, but that has no effect on what the parent class or any
>> other sees as the value of the parent-class variable.
>>
>
> Interesting objection - that's actually what I meant saying "override".
> Let's try something else: There's a module "module_x" and these
> directories: $moduledir/module_x/manifests/ and there's an "init.pp" with
> this content:
>
> class module_x {
> include module_x::child
> include module_x::another_child
> include module_x::another_child2
> include module_x::another_child3
> ...
> }
>
> There's also a file 'constant.pp' containing this
>
> class module_x::constant {
> $var = 'value'
> }
>
> Class module_x::constant is not included. Classes like module_x::child
> should be able to inherit the default value of $var but also be able to
> hide it within their own scope by declaring a same-named local variable.
> It would look like this:
>
> class module_x::child inherits module_x::constant {
> // wants to use a default value for $var but should be able to hide it
> within their own scope.
> }
>
>
> Something wrong with that?
>
There is nothing inherently wrong with it. There is only a question of
whether it means what you want it to mean. There are two main questions to
consider:
1. in any given context of interest, what does the unqualified variable
reference $var mean?
2. what does (for example) $module_x::child::var mean?
Suppose you have this version of module_x::child:
class module_x::child inherits module_x::common {
# no local declaration of variable $var
}
Then,
- in class module_x::child, $var resolves to $module_x::common::var, and
- variable $module_x::child::var is undefined (everywhere)
On the other hand, if module_x::child looks like this:
class module_x::child inherits module_x::common {
$var = 'my value'
}
then,
- in class module_x::child, $var resolves to $module_x::child::var, and
- variable $module_x::child::var is defined (everywhere, subject to
parse order), and has the specified value, which may or may not differ from
the value of $module_x::common::var
Classes other than module_x::child and any others that inherit from it see
no difference between the two cases.
John
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