On Jan 19, 2:17 pm, Nick Fagerlund <nick.fagerl...@puppetlabs.com>
wrote:
> On Jan 19, 11:01 am, "R.I.Pienaar" <r...@devco.net> wrote:
>
> > ----- Original Message -----
> > > Defined() doesn't suck! It's a 100% reliable way to check what
> > > classes and defined types are available to the autoloader. I challenge
> > > anyone
> > > to find me an example of this usage that fails.
>
> > can you give an example of this use case pls?
>
> Well... that's something I realized after I posted that, is I'm not
> sure if anyone WANTS a reliable way to test the autoloader. (Obviously
> people do want a way to check for resource instances, which is why
> defined() keeps getting used for that...)
>
> But anyway! Say you make a module for a network service and you want
> it to be able to manage its own firewall rule. You know of a defined
> type for firewall rules, and you're using it, but you want your module
> to be portable and you know of good reasons why someone wouldn't be
> using your iptables module.
>
> So, you can conditionally declare the rule if the defined type is
> available to the autoloader, and otherwise you don't attempt to manage
> the firewall and expect that the user has read the documentation and
> will make a hole for the service themselves.
>
> if defined(firewall::iptables::rule) {
> firewall::iptables::rule {'mysql_server':
> ...etc. etc.
> }
>
> }
>
> See? It's just a way to peek around at what the user has installed.
>
> Which... maybe implies that it should be renamed to "installed()."
> Dunno.
I don't think I would ever write code like that myself. I would
rather document module and class dependencies, and expect to have
catalog compilation fail if I try to use classes or other module
features whose documented dependencies are not available. That's a
style and best practices position, however. I would be satisfied to
have only defined()'s support for resource references be deprecated.
Alternatively, defined() could be wholly deprecated, but a new
function (e.g. "installed()") introduced that is a work-alike except
for not accepting resource references.
John
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