How to use `getproperty`/`setproperty!`?

[stevengj]

@e3c6

Or is the compiler able to eliminate the branching when it sees a.b (hence knows the actual symbol used)?

Yes, the compiler normally inlines and eliminates the branches when you call getproperty via a.b. (This is a constant-propagation optimization that was added in Julia 0.7.)