SWIG - 使用 %newobject 的垃圾收集 [英] SWIG - Garbage Collection using %newobject

问题描述

在我的 C 代码中，我有以下结构:

In my C code, I have the following structure :

typedef struct my_structure{
    char* str1;
    char* str2;
}MyStruct;

还有一个返回 MyStruct 指针的函数:

And a function that returns a MyStruct pointer :

MyStruct* foo();

在foo里面，我已经为MyStruct、str1和str2分配了内存，如下:

Inside foo, I have allocated memory for MyStruct , str1 and str2, as follows:

MyStruct* obj = malloc(sizeof(MyStruct));

obj.str1 = malloc(256);
obj.str2 = malloc(256);

我想从 python、java、C# 和 PHP 调用 foo 并且我不想在这个过程中有任何内存泄漏.

I want to call foo from python, java, C# and PHP and I don't want to have any memory leak in this process.

我不确定是否写:

%newobject foo;
MyStruct* foo();

保证垃圾收集器将为结构和其中的字符串释放内存.

guarantees that the garbage collector will free memory for both the structure and the strings inside it.

我不想让调用者有义务为 str1 和 str2 显式释放内存，因为我正在寻找一种自动释放内存的方法.这可能吗?

I didn't want to obligate the caller to explicit free memory for str1 and str2 as I was looking for an automatic way of freeing memory. Is this possible?

在这种情况下，我必须使用newfree"类型映射吗?

Do I have to use "newfree" typemap in this case?

如果您能提供一个示例来展示实现此目的的最佳方法，我将不胜感激.

I would greatly appreciate if you could provide me an example showing the best way to accomplish this.

谢谢！

推荐答案

typemap(newfree) 立即释放返回的 %newobject 使用的内存，例如当 achar* 返回值转换为 Python 字符串，不再需要分配的对象.我认为您想要的是 %extend SWIG 围绕您的 C 结构生成的类包装器以提供析构函数:

typemap(newfree) frees the memory used by the returned %newobject immediately, such as when a char* return value is converted into a Python string and the allocated object is no longer needed. I think what you want is %extend the class wrapper that SWIG generates around your C structure to provide a destructor:

%newobject foo;

%extend MyStruct {
    ~MyStruct() {
       free($self->str1);
       free($self->str2);
    }
}

如果这解决了您的问题，请发表评论.这是基于我自己对 SWIG 文档中的内容进行的实验，并在我生成的简单包装器中正常工作.

Please comment if this solves your issue. This is based on my own experimentation with what I could find in the SWIG documentation and worked correctly in the simple wrapper I generated.

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