SWIG,C和Python：C临时对象过早删除

概述我有一个SWIG过早删除临时C对象的问题. Python测试脚本的示例输出： --------------------------------------------------------------------------------Works as expected: b0 = Buffer(0, 0, 0, ) b1 = Buffer(1, 1, 1, ) b 我有一个SWIG过早删除临时C对象的问题.

Python测试脚本的示例输出：

--------------------------------------------------------------------------------Works as expected:    b0 =  Buffer(0,)    b1 =  Buffer(1,1,)    b0 =  Buffer(0,)    y  =  Buffer(0,)    repr(b0) =  Buffer(ID = 0,vector at 0x020bf450,data at 0x020aeb30,size = 6)    repr(y)  =  Buffer(ID = 0,size = 6)Funny business:    Deleting Buffer(ID = 2)    Deleting Buffer(ID = 3)    repr(b2) =  Buffer(ID = 2,vector at 0x020bf790,data at 0x00,size = 4257068)    Deleting Buffer(ID = 4)    repr(b3) =  Buffer(ID = 4,vector at 0x02037040,data at 0x0204a4e0,size = 6)    Deleting Buffer(ID = 0)    Deleting Buffer(ID = 1)

删除缓冲区(ID = X)是从Buffer :: ~Buffer()C代码中生成的,所以我们在这里可以看到,在Funny业务部分,C Buffer对象被过早删除了！ Python对象b2和b3应该保持对ID = 2和ID = 4的C Buffer对象的引用.

我的所有代码都附在我的博客post上.但是,我将在这里总结一下代码：

Buffer.hpp：

#include <vector>#include <string>struct Buffer{    Buffer();    Buffer(const Buffer & copy);    ~Buffer();    Buffer & operator=(const Buffer & rhs);    Buffer & operator<<(const Buffer & rhs);    Buffer & operator<<(double rhs);    std::string __str__() const;    std::string __repr__() const;    private:    std::vector<double> _data;    int                 _ID;};

swig_test.i：

%module swig_test%include "std_string.i"%{    #include "Buffer.hpp"    #include <iostream>%}%ignore Buffer::operator=;%include "Buffer.hpp"

go_test.py：

from swig_test import Bufferdef zeros(n):    '''    Returns a Buffer filled with 'n' zeros.    '''    b = Buffer()    for i in xrange(n):        b << 0.0    return bdef ones(n):    '''    Returns a Buffer filled with 'n' ones.    '''    b = Buffer()    for i in xrange(n):        b << 1.0    return bdef main():    #--------------------------------------------------------------------------    # This sections works as expected    print "-" * 80    print "Works as expected:"    b0 = zeros(3)    print "    b0 = ",b0    b1 = ones(3)    print "    b1 = ",b1    y = b0 << b1    print "    b0 = ",b0    print "    y  = ",y    print "    b1 = ",b1    print "    repr(b0) = ",repr(b0)    print "    repr(y)  = ",repr(y)    #--------------------------------------------------------------------------    # Funny things are happening here!    print "Funny business:"    b2 = zeros(3) << ones(3)    print "    repr(b2) = ",repr(b2)    b3 = zeros(3) << 4.0    print "    repr(b3) = ",repr(b3)if __name__ == "__main__":    main()

我在博客文章中已经尝试了一些SWIG的东西,但我的SWIG-foo技能已经缩短了.

救救我社区,你是我唯一的希望！

更新1

我怀疑我有多个PyObjects将Buffer *保存到同一个C Buffer对象,所以当临时PyObject被垃圾收集时,它会删除C Buffer *.

所以,我想我需要一个Py_INCREF,但在哪里呢？

更新2

尝试按照jarod42的建议按值返回会破坏串联范例,例如：

b = Buffer()b << 1 << 2 << 3print b

只生产：

Buffer(1,)

所以这不是我想要的.

％newobject指令可用于释放函数或方法创建的新创建的对象(防止内存泄漏).在这种情况下,Buffer :: operator<<没有创建新对象.

解决方法 经过一番搜索后,我遇到了这个 thread,最终导致了一个有效的解决方案.

将typemap(out)与Py_INCREF结合使用就可以了.

swig_test.i：

%module swig_test%include "std_string.i"%{    #include "Buffer.hpp"    #include <iostream>%}%ignore Buffer::operator=;%typemap(out) Buffer & operator<<{    if(result) { /* suppress unused warning */ }    Py_INCREF($self);    $result = $self;}%include "Buffer.hpp"

现在我得到了我想要的行为(它与纯Python实现相匹配)并且没有内存泄漏.

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