Recently (about 5 minutes ago), I was writing a custom puppet-function to offload some puppet magic. In short: I’m writing a wrapper around create_resources so I can keep syntax for the end-users of my module crispy clean. This means I need the create_resources function to be available in my custom function. This can be done by using Puppet::Parser::Functions.autoloader.loadall as suggested on the puppetlabs custom modules guide. Unfortunately, when using #loadall, all functions will be loaded.
Why unfortunately? In my case: A function defined in puppet-foreman depends on the rest-client gem and I do not have this installed. Some people might say: Just install the gem and be done with it! This is hardly a proper solution. The way to go would to be only include the function I really need, being create_resources.
And here is how:
Puppet::Parser::Functions.autoloader.load(:create_resources) unless Puppet::Parser::Functions.autoloader.loaded?(:create_resources)
This will basically load the create_resources function after checking that it has not been loaded before. This (the function already being loaded) could be the case if you properly depend on puppetlabs-create_resources in your manifests. Side note: I added a small dummy class so my modules can depend on this function being available.
This has resolved my issues with #loadall, but if I ever needed to include another function that DOES use #loadall, I’ll be screwed all over again. So (pretty) pls, don’t use #loadall.
Just for the record, we removed that dependency on rest-client a while ago from the foreman function :)
 – http://theforeman.org/issues/1408
If not yet done, you should probably file a ticket @ puppetlab’s documentation bugtracker: https://projects.puppetlabs.com/projects/puppet-docs
I think it would be better if the official documentation would recommend to only load functions that are actually needed.