如何使用SWIG生成跨平台接口？

Question

I'm wrapping a library with SWIG (Python as target). The library functions contains parameters with the datatypes "uint32_t", "uint8_t", etc. I want to create the interface as cross-platform as possible, so I want to use the original function signatures in my interface.i file. For example:

uint32_t func(uint32_t a, uint32_t b);

The issue I'm trying to solve is that SWIG won't recognize the parameter as an integer unless there is a typedef on the uint32_t datatype. Right now I'm using this on the interface file:

typedef unsigned uint32_t;

Removing that typedef line will cause the function not to be callable from the target Python binding:

>>> mylib.func(2, 2)
TypeError: in method 'func', argument 1 of type 'uint32_t'

The previous typedef is OK on my local machine, but might be different on another compiler/platform. Using the directive %include "stdint.h" will raise an error on SWIG:

/usr/include/stdint.h:44: Error: Syntax error in input(1).

Wich makes sense since SWIG is not a full-featured compiler, and can not fully evaluate all the #ifdef on that header.

How can I correctly feed SWIG with the datatypes the compiler is choosing on the stdint.h header? Does in fact make sense to strictly enforce the correct datatypes, or just typedef ing all the intX_t to long is OK?

Answer 1

If you want to use these types in your SWIG interface file you can do something like:

%module test
%include "stdint.i"

uint32_t my_function();

Which is an existing SWIG interface has the correct typedef s for your system.

Answer 2

You should force typedef because uint32_t is not cross platform and not cross compiler. uint32_t is C99 standard but many compilers decided not to implement completely this standard. You can have an include to redefine in a cross compiler way your project types:

http://www.azillionmonkeys.com/qed/pstdint.h

It is worth to read the introduction of the header I linked above. You could use this include instead of stdint.h.

You can also read this question:

Cross-platform primitive data types in C++