Passing ctypes pointers between workers is painfull.
I asked around how we are doing in existing firefox codebase. The eval() of this string doesn't look like the best practice.
Here is what they are doing:

 * on the sender side:
`myStr = ctypes.cast(myPointer, ctypes.uintn_t).value.toString()`
 * on the receiver side:
`myPointer = ctypes.cast(ctypes.uintn_t(myStr), atransport.ptr)`

We are converting the pointer to a integer, but as JS integers aren't big enough on 64bits, we end up having o stringify the big int...