Since we focus on safety, it would be nice to reduce the chance of any
runtime errors if we made a typo for a resource parameter. With this
patch, each resource can export constants into the global namespace so
that typos would cause a compile error.
Of course in the future if we had a more advanced type system, then we
could support precise types for each individual resource param, but in
an attempt to keep things simple, we'll leave that for another day. It
would add complexity too if we ever wanted to store a parameter
externally.
Lastly, we might consider adding "special case" parsing so that directly
specified fields would parse intelligently. For example, we could allow:
file "/tmp/hello" {
state => exists, # magic sugar!
}
This isn't supported for now, but if it works after all the other parser
changes have been made, it might be something to consider.
This adds a "purge" parameter to the file resource. To do this, we have
to add the API hooks so the file resource can query other resources in
the graph to know if they are present, and as a result whether they
should be excluded from the purge or not.
This is useful for when we have a managed directory with some managed
contents. If a managed file is removed from the directory, then it will
be removed by the file (directory) resource if it has Purge set.
Alternatively, you can use the Reverse meta param, which is sometimes
preferable for this use case and sometimes not. This will be discussed
elsewhere.
This also adds a bunch of tests for this feature.
This also makes a few somewhat related cleanups in the file code.
