`Module#private_class_method` takes a symbol representing the name of a
method in the current module scope and makes that module private. This
is similar to `private`, but applies only to class (singleton) methods.
Unlike `private`, it must be called with an argument, and does not
change the ambient visibility for any subsequent method definitions.
class Foo
def public
end
def private1
end
private_class_method :private1
# This alternate form works because method definition
# returns its name as a symbol:
private_class_method def private2
end
end
A few changes, all bundled together:
- We were getting a lot of magic applied to the predicates in the
`ImportStar` module, and this was causing needless re-evaluation.
To address this, the easiest solution was to simply cache the entire
module.
- In order to separate this from the dataflow analysis and make it
dependent only on control flow, `potentialImportStarBase` was changed
to return a `ControlFlowNode`.
- `isDefinedLocally` was defined on control flow nodes, which meant we
were duplicating a lot of tuples due to control flow splitting, to no
actual benefit.
Finally, there was a really bad join in `isDefinedLocally` that was
fixed by separating out a helper predicate. This is a case where we
could use a three-way join, since the join between the `Scope`, the
`name` string and the `Name` is big no matter what.
If we join `scope_defines_name` with `n.getId()`, we'll get `Name`s
belonging to irrelevant scopes.
If we join `scope_defines_name` with the enclosing scope of the `Name`
`n`, then we'll get this also for `Name`s that don't share their `getId`
with the local variable defined in the scope.
If we join `n.getId()` with `n.getScope()...` then we'll get all
enclosing scopes for each `Name`.
The last of these is what we currently have. It's not terrible, but not
great either. (Though thankfully it's rare to have lots of enclosing
scopes.)
