我正在使用SWIG和boost共享指针来创建python扩展。我目前的问题是SWIG_SHARED_PTR宏似乎与模板化的类不同。我将举两个例子，一个没有模板（例子），一个带模板（例子2）。
首先，我将包含代码，最后显示python中两个扩展的行为差异。
基本问题是没有模板，共享指针在python中显示为
<example.Derived; proxy of <Swig Object of type 'derived_sptr *' at 0xb772c4b8> >
而当包装类是实例化模板时，显示为
<Swig Object of type 'derived_int_sptr *' at 0xb787e4b8>
我是C ++模板的新手，所以很有可能我遇到的问题与SWIG无关。
没有模板（工作正常）
example.h文件
#include <boost/shared_ptr.hpp>
#ifndef EXAMPLE_H
#define EXAMPLE_H
class Base {
public:
Base(int number1);
int get_number1();
virtual int get_number2() = 0;
protected:
int number1;
};
class Derived : public Base {
public:
Derived(int number1, int number2);
int get_number2();
private:
int number2;
};
typedef boost::shared_ptr<Base> base_sptr;
typedef boost::shared_ptr<Derived> derived_sptr;
derived_sptr make_derived(int number1, int number2);
int get_number1(base_sptr b);
#endif
example.cc
#include "example.h"
Base::Base(int number1) :
number1(number1)
{}
int Base::get_number1() {
return number1;
}
Derived::Derived(int number1, int number2) :
Base(number1),
number2(number2)
{}
int Derived::get_number2() {
return number2;
}
derived_sptr make_derived(int number1, int number2) {
return derived_sptr(new Derived(number1, number2));
}
int get_number1(base_sptr b) {
return b->get_number1();
}
example.i
%module example
%{
#include "example.h"
%}
%include boost_shared_ptr.i
SWIG_SHARED_PTR(base_sptr, Base)
SWIG_SHARED_PTR_DERIVED(derived_sptr, Base, Derived)
%include example.h
使用模板（不起作用）
example2.h
#include <boost/shared_ptr.hpp>
#ifndef EXAMPLE2_H
#define EXAMPLE2_H
template <typename T>
class Base {
public:
Base(T number1);
T get_number1();
virtual T get_number2() = 0;
protected:
T number1;
};
template <typename T>
class Derived : public Base<T> {
public:
Derived(T number1, T number2);
T get_number2();
private:
T number2;
};
typedef Base<int> base_int;
typedef Derived<int> derived_int;
typedef boost::shared_ptr<base_int> base_int_sptr;
typedef boost::shared_ptr<derived_int> derived_int_sptr;
derived_int_sptr make_derived_int(int number1, int number2);
int get_number1_int(base_int_sptr b);
#endif
example2.cc
#include "example2.h"
template <typename T>
Base<T>::Base(T number1) :
number1(number1)
{}
template <typename T>
T Base<T>::get_number1() {
return number1;
}
template <typename T>
Derived<T>::Derived(T number1, T number2) :
Base<T>(number1),
number2(number2)
{}
template <typename T>
T Derived<T>::get_number2() {
return number2;
}
template class Base<int>;
template class Derived<int>;
derived_int_sptr make_derived_int(int number1, int number2) {
return derived_int_sptr(new Derived<int>(number1, number2));
}
int get_number1_int(base_int_sptr b) {
return b->get_number1();
}
example2.i
%module example2
%{
#include "example2.h"
%}
%include boost_shared_ptr.i
SWIG_SHARED_PTR(base_int_sptr, base_int)
SWIG_SHARED_PTR_DERIVED(derived_int_sptr, base_int, derived_int)
%include example.h
%template(base_int) Base<int>;
%template(derived_int) Derived<int>;
差异示例：
> import example
> d = example.make_derived(4, 5)
> d
> <example.Derived; proxy of <Swig Object of type 'derived_sptr *' at 0xb77327a0> >
> d.get_number1()
4
> example.get_number1(d)
4
> import example2
> d = example2.make_derived_int(4, 5)
> d
<Swig Object of type 'derived_int_sptr *' at 0xb787e4b8>
> d.get_number1()
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: 'SwigPyObject' object has no attribute 'get_number1'
> example.get_number1_int(d)
4
答案 0 :(得分：1)
SWIG对内部类型系统对象暴露于它的顺序非常敏感。
尝试移动%template语句，使其位于SWIG_SHARED_PTR语句之前。
答案 1 :(得分：0)
在example2.i中的行
SWIG_SHARED_PTR(base_int_sptr, base_int)
SWIG_SHARED_PTR_DERIVED(derived_int_sptr, base_int, derived_int)
应替换为
SWIG_SHARED_PTR(base_int_sptr, Base<int>)
SWIG_SHARED_PTR_DERIVED(derived_int_sptr, Base<int>, Derived<int>)