There was a problem in that creating a subclass in R of an Rcpp class
attempts to call a default constructor.
I have code that fixed the problem, by creating a suitable $initialize()
method based on the existence or not of the default C++ constructor, but
unfortunately I have yet to fully test & commit the change, and I'm off
in a few minutes for today.
So, sorry, you probably still need a default constructor as a workaround
if you intend to define a subclass but, with luck, soon you won't.
John
On 11/19/10 7:06 AM, Douglas Bates wrote:
I believe it is now recommended that a class to be exposed in a module
should expose a default constructor (i.e. a constructor called with no
arguments). Is such a constructor actually called or is it just there
to establish the necessary linkage? In a class where it would not
make sense to construct an object without arguments I was going to
have the default constructor throw an exception but that might not be
a good idea. I seem to recall the discussion between John and Romain
indicating that it must be called during the initialization of the
reference class in R.