%typemapping of a C++ Library for Python Interface

Question

I want to create a python wrapper for my C++ library. It would be cool, if there is a automatic conversion of std::vector to python lists and the other way round. Unfortunatly

Answer 1

If you're going to define the %typemaps manually, you will also need a %typemap(check), something like:

%typemap(typecheck) std::vector<float>& {
    $1 = PySequence_Check($input) ? 1 : 0;
}

I believe the rule of thumb is that if you define a %typemap(in), you should also define a %typemap(check) --- otherwise, the generated code never gets to where it's put your %typemap(in).

Answer 2

The std_vector.i library in SWIG provides support for std::vector.

http://www.swig.org/Doc2.0/Library.html#Library_stl_cpp_library

You just need to tell SWIG about the template instantiations you want it to know about:

%include "std_vector.i"

namespace std {
    %template(FloatVector) vector<float>;
}

Note that the following Python code will work, but will incur an array copy:

for x in range(0, 3):
    list[x] = x
myModule.myFunction(list)

To do the same thing without incurring a copy, construct the list using the SWIG-generated proxy object constructor:

list = myModule.FloatVector()
for x in range(0, 3):
    list[x] = x
myModule.myFunction(list)