C API的设计：谁应该分配？ [英] C API design: Who should allocate?

问题描述

什么是正确的/ preferred在一个C API分配内存的方式？

What is the proper/preferred way to allocate memory in a C API?

我可以看到，起初，两个选项：

I can see, at first, two options:

1）让主叫方做所有的（外）内存处理：

1) Let the caller do all the (outer) memory handling:

myStruct *s = malloc(sizeof(s));
myStruct_init(s);

myStruct_foo(s);

myStruct_destroy(s);
free(s);

的 _init 和 _destroy 功能是必要的，因为一些更多的内存可以被内部分配，它必须被处理什么地方。

The _init and _destroy functions are necessary since some more memory may be allocated inside, and it must be handled somewhere.

这具有作为长的缺点，但也malloc的可在某些情况下（例如，它可以传递一个堆栈分配结构来消除：

This has the disadvantage of being longer, but also the malloc can be eliminated in some cases (e.g., it can be passed a stack-allocated struct:

int bar() {
    myStruct s;
    myStruct_init(&s);

    myStruct_foo(&s);

    myStruct_destroy(&s);
}

此外，这是必要的来电者知道结构的大小。

Also, it's necessary for the caller to know the size of the struct.

2）隐藏的malloc 在 _init 和免费 S IN _destroy 。

2) Hide mallocs in _init and frees in _destroy.

优点：更短的code，因为函数将被称为反正。完全不透明的结构。

Advantages: shorter code, since the functions are going to be called anyway. Completely opaque structures.

缺点：不能顺利通过以不同的方式分配的结构

Disadvantages: Can't be passed a struct allocated in a different way.

myStruct *s = myStruct_init();

myStruct_foo(s);

myStruct_destroy(foo);

我目前倾向对于第一种情况;还是那句话，我不知道C API设计的。

I'm currently leaning for the first case; then again, I don't know about C API design.

推荐答案

我最喜欢的一个精心设计的C API的例子是 GTK + 它采用方法＃2你描述。

My favourite example of a well-design C API is GTK+ which uses method #2 that you describe.

虽然你的方法＃1的另一个优点是不只是你可以分配堆栈上的对象，还以为你可以的再利用的同一个实例多次。如果这不会是一个常见的​​情况，那么，＃2简单可能是一个优势。

Although another advantage of your method #1 is not just that you could allocate the object on the stack, but also that you could reuse the same instance multiple times. If that's not going to be a common use case, then the simplicity of #2 is probably an advantage.

当然，这只是我的意见：）

Of course, that's just my opinion :)

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