Re: [Swig-user] typemap problem: can't get arrays example to work

[Russell E. O. <ro...@uw...>]

In article <row...@ne...>,
 "Russell E. Owen" <ro...@uw...> wrote:

> I'm hoping somebody will eventually wrap std::array (much like 
> std_vector.i). Meanwhile I'll use the appended hack, adapted from 
> <http://stackoverflow.com/questions/7713318/nested-structure-array-access
> -in-python-using-swig>. It has some unfortunate limitations: no way to 
> set all values at once, no range indexing, no relative indexing. But it 
> works and it certainly avoids excessive copying.

I was able to overcome these problems using the appended .i excerpt. The 
resulting Python is as clean as I could hope for. One can do things like:
test.d[:] = (1, 2, 3)
atuple = test.d[:]
test.d[0] = 1
test.d[-1] = 3.0
...
One cannot do this: test.d = (1, 2, 3) but I am fine with that because 
one cannot rebind test.d in any case.

The C++ side is not ideal because of the array data is one level down 
from where it should be: in my example test.d.arr instead of test.d.

I tried wrapping boost::array directly to make the C++ look normal, but 
unsurprisingly got an enormous number of errors -- enough to convince me 
to live with my simple solution for now. I hope somebody more familiar 
with SWIG will be able to figure out how to wrap std::array (the modern 
version of boost::array).

-- Russell

%extend tcc::swigArray {
    inline size_t __len__() const { return N; }
    
    inline const Type& _get(size_t i) const throw(std::out_of_range) {
        return $self->arr.at(i);
    }
    
    inline void _set(size_t i, const Type& v) throw(std::out_of_range) {
        $self->arr.at(i) = v;
    }
    %pythoncode {
        def __getitem__(self, key):
            if isinstance(key, slice):
                return tuple(self._get(i) for i in 
range(*key.indices(len(self))))

            if key < 0:
                key += len(self)
            return self._get(key)
        
        def __setitem__(self, key, v):
            if isinstance(key, slice):
                for i in range(*key.indices(len(self))):
                    self._set(i, v[i])
            else:
                if key < 0:
                    key += len(self)
                self._set(key, v)
    }
}

%template (swigArray_int_2) tcc::swigArray<int, 2>;
%template (swigArray_int_3) tcc::swigArray<int, 3>;
%template (swigArray_double_2) tcc::swigArray<double, 2>;
%template (swigArray_double_3) tcc::swigArray<double, 3>;