Re: [Boost-users] how to pass pointer to boost.python function in python?

From: David Abrahams (dave_at_[hidden])
Date: 2006-09-05 20:03:18

"Qinfeng(Javen) Shi " <shiqinfeng_at_[hidden]> writes:

> Dear all,
>
> I wraped a v_varray class into python by boost.
> I called it in python, most of its attributes work well. Only when I call
> a.push(1.0),it crashed  due to  not match  type.

For the record, that's not a crash.

> The problem is that my input
> argument in c++ is float*(for passing an array) while python has no pointer
> type.

That's one way to look at it.

> How can I pass a variable in python to a.push() to make sure it work
> correctly?

Depends what you mean by "work correctly."  You need to decide what
semantics you want.  If you want your float to be treated as an array
of one element, you could use a "thin wrapper":

   void push(v_array<float*>& self, float x) { self.push(&x); }

   class_<v_array<float*> >("array_floatstar")
      .def("push", push)
      ...
      ;

Of course, any modifications push makes to the float at the other end
of the non-const pointer will be lost.

Oh, and future Boost.Python questions should probably be directed to
the C++-sig: http://www.boost.org/more/mailing_lists.htm#cplussig

HTH,
-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com