Boost::python: implicit conversions

From: Peter.Bienstman_at_[hidden]
Date: 2001-07-17 10:21:05

Hi,

This is another installment in my exploration of the boundaries of 
boost::python.

Consider

  class_builder<Term> Term_(module, "Term");
  Term_.def(constructor<>());

  class_builder<Expression> Expression_(module, "Expression");
  Expression_.def(constructor<>());
  Expression_.def(constructor<const Term&>());

  class_builder<User> User_(module, "User");
  User_.def(constructor<const Expression&>();

Using the original C++ code, I could write

  Term t=Term();
  User u=User(t);

, because C++ is smart enough to figure out how to construct an 
Expression from a Term.

Now, trying the same in Python, we get

>>>t = Term()
>>>u = User(t)

TypeError: extension class 'Term' is not convertible 
into 'Expression'.

Short of modifying the original C++ code to add a User::User(const 
Term&) constructor, is there anything I can do to get the Boost 
typesystem to apply Expression::Expression(const Term&) for me?

Thanks,

Peter