Ruby and C++

hey everyone,
im trying to write a script as well as a program each of which can
communicate with one another. the script should be able to have access
to the class in my c++ code. just a simple class with a couple of
variable and some accessors and modifiers for them. i want to be able
to create an object of that class type in the script and call the
classes functions in order to manipulate the data. at this point i can
create an object in the script and it seems that i can modify the object
through the set methods, but when i call the get method for that
function it get an error saying it is expecting the class type as the
return type(i assume thats what the error means… “in ‘getInt’: wrong
type - expected DummieClass”)
for all of my set methods i return self. for the get methods i return a
VALUE object which should be holding the value of the class member i am
working with.


c++ code:

static VALUE _wrap_get_int(VALUE self)
{
GET_MY_CLASS(self); //a macro that returns an instance pointer of
my class

//this function call returns a VALUE after converting the c++ int
return GetRubyInt(pDummie->getInt());

}


ruby script:

obj = SimpleExt::Dummie.new(12,3.4, “my String”)
obj.setInt(100)
x = obj.getInt()

print x


it seems to be crashing out when it gets to the line x = obj.getInt().
can anyone tell me whats wrong with this, or am i going about this the
wrong way? im thinking that i may have to change my c++ code around,
but i dont know. if anyone could lend some adive i would appreciate it.
thanks
steveD

I can’t speak to the specific problem you’re running into. However, I
can recommend using SWIG for this sort of thing. I think it makes this
kind of integration much easier. I created a presentation on this that
you can read at http://www.ociweb.com/jnb/jnbJan2006.html. It mostly
focuses on using SWIG to invoke C++ from Java, but at the end there is
a Ruby example.

On 1/18/06, SteveD [email protected] wrote:

return type(i assume thats what the error means… "in ‘getInt’: wrong
GET_MY_CLASS(self); //a macro that returns an instance pointer of
obj.setInt(100)
x = obj.getInt()

print x


it seems to be crashing out when it gets to the line x = obj.getInt().
can anyone tell me whats wrong with this, or am i going about this the
wrong way? im thinking that i may have to change my c++ code around,
but i dont know. if anyone could lend some adive i would appreciate it.

It would help if you could post the entire code. Or at least, some
sample code that exhibits the same behavior.

On Thu, Jan 19, 2006 at 01:16:14AM +0900, SteveD wrote:

classes functions in order to manipulate the data. at this point i can
create an object in the script and it seems that i can modify the object
through the set methods, but when i call the get method for that
function it get an error saying it is expecting the class type as the
return type(i assume thats what the error means… “in ‘getInt’: wrong
type - expected DummieClass”)

I suspect that it is the GET_MY_CLASS line that is raising the
exception, so this probably has nothing to do with your return value.

As someone else pointed out, posting a complete minimal solution that
reproduces the problem along with the exact output and the expected
output is usually helpful in tracking these things down (plus sometimes
when I put something like that together, I find the problem before I
even post!)

Paul

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