How to translate a union inside a struct from c++ to python with SIP?

Question

I answered this question explaining how to translate a union from c++ to python with SIP (unions are not automatically supported).

When I use this type of wrapping for a union inside an existing struct I get the following error message when I try to build with sip-install (I renamed 'wrapped_u' to 'u' and 'test_u' to 'type_u'):

error: field 'u' has incomplete type 'type_u'

and

note: forward declaration of 'union type_u' .

Here it the c++ header file:

struct myType{

    enum {CHAR, INT, DOUBLE} tag;
    union type_u{
        /* tag = CHAR */
        char char_value;
        /* tag = INT */
        int int_value;
        /* tag = DOUBLE */
        double double_value;
    };
    type_u u;
    void print_my_type() const;
};

and this is the SIP file:

struct myType{

    enum tag {CHAR, INT, DOUBLE};

    struct union_wrapper /PyName=type_u/
    {
        %TypeHeaderCode
        #include <test_struct_union.h>

        struct union_wrapper
        {
             union type_u u;
        };
    %End

        // tag = CHAR
        char char_value {
        %GetCode
            sipPy = PyUnicode_FromString(&(sipCpp->u.char_value));
        %End
        %SetCode
            if (PyUnicode_Check(sipPy))
                sipCpp->u.char_value;
            else
                sipErr = 1;
        %End
        };
        // tag = INT
        int int_value {
        %GetCode
            sipPy = PyLong_FromLong(sipCpp->u.int_value);
        %End
        %SetCode
            if (PyLong_Check(sipPy))
                sipCpp->u.int_value;
            else
                sipErr = 1;
        %End
        };

        // tag = DOUBLE
        double double_value {
        %GetCode
            sipPy = PyFloat_FromDouble(sipCpp->u.double_value);
        %End
        %SetCode
            if (PyFloat_Check(sipPy))
                sipCpp->u.double_value;
            else
                sipErr = 1;
        %End
        };
    };

    void print_my_type() const;
};

Does someone know how to solve this?

Thank you in advance!

Johnny

Answer 1

Unions are supported since Sip version 6.0.0.

Thank you for the quick integration Riverbank Computing.

Hopefully the manual way to do the translation will not be necessary any more.