带模板类的SWIG_SHARED_PTR宏
我正在使用SWIG和boost共享指针来创建Python扩展。现在我遇到的问题是，SWIG_SHARED_PTR宏在处理模板类时似乎表现得不太一样。我会给出两个例子，一个是没有模板的（例子），另一个是有模板的（例子2）。
首先，我会包含代码，最后展示这两个扩展在Python中的行为差异。
基本问题是，没有模板时，共享指针在Python中显示为：
<example.Derived; proxy of <Swig Object of type 'derived_sptr *' at 0xb772c4b8> >
而当被包装的类是一个实例化的模板时，它们显示为：
<Swig Object of type 'derived_int_sptr *' at 0xb787e4b8>
我对C++模板还很陌生，所以我遇到的问题可能和SWIG没有关系。
没有模板的情况（正常工作）
example.h
#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
有模板的情况（不正常工作）
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
2 个回答
1
SWIG在处理对象时，对它们的顺序要求比较严格，这跟它内部的类型系统有关。
你可以试着把你的%template语句放在SWIG_SHARED_PTR语句之前。
0
在example2.i中，下面这几行
SWIG_SHARED_PTR(base_int_sptr, base_int)
SWIG_SHARED_PTR_DERIVED(derived_int_sptr, base_int, derived_int)
应该替换成
SWIG_SHARED_PTR(base_int_sptr, Base<int>)
SWIG_SHARED_PTR_DERIVED(derived_int_sptr, Base<int>, Derived<int>)