R6 Methods in FunctionReporter

[jayqi]

Resolves #123

Summary of changes:

• Added support for R6 class methods in FunctionReporter. Some design choices/constraints:
  • Class names are the name of the generator object in the package namespace, and not the classname attribute. This is because the classname attribute is not required to be defined and also not required to match the generator object name, though people conventionally do assign one with the same name.
  • Nodes have names of the form <classname>$<methodtype>$<methodname>, e.g., FunctionReporter$private_methods$extract_nodes .
  • Methods only ever show up as one node even with inheritance, unless the child class overrides with a new definition. Inherited methods are assigned to the class in which they were defined, and not for any child classes
  • Dependency on calls to instantiated objects' methods are not supported. Instantiated objects can have arbitrary names and I don't want to deal with it right now.
• Added test package milne for testing R6 classes
• Changed the .gitignore entries for data files to only exclude data files in package root. Want to be able to commit test data in tests. Added .gitignore exclusion for csv files in tests/testthat/testdata directory.

Not addressed in this PR. Maybe for discussion in issues after merging.

• Calls to object constructors by functions are ignored right now, like FunctionReporter$new() in DefaultReporters? Not clear the right way to represent these. Does that edge link to the initialize method for that class? FunctionReporter has no initialize method, so would we link the edge to the initialize method inherited up the ancestor sequence? But actually none of its ancestors have an initialize method defined -- they're all using the vanilla one built-in to R6. So there isn't even a node right now for it.

[jameslamb]

This is awesome! I added a few comments

[jayqi]

@jameslamb Addressed your comments! Thanks for reviewing.

[jameslamb]

This is good with me! Will leave it to @bburns632 to do one more pass and and smash merge, since this is a decent-sized PR

[bburns632]

@jayqi this PR brings to light the bottom depths of an R package. It is the next level of insight into a package. Excellent work.

AND I look forward to PR #129 to add some structure to these newly surfaced elements.

Here's master currently for a pkgnet report on pkgnet:

Here's the same report with changes from this PR: