成员访问不完整类型错误 [英] Member access into incomplete type error

问题描述

我有以下文件结构，其中包含一个封装类型的结构定义，当我尝试访问该结构的成员时，我将成员访问权限转换为不完整类型错误。问题是什么？

I have the following files structure that contain the definition of a struct an encapsulating type, when I try to access a member of the struct, I get the Member access into incomplete type error. What is the problem?

foo_encoder.c ：

#include "foo.h"
//...
struct FooEncoder {
  int A;
  int B;
  foo_int32 C;
  //...
}

foo.h ：

extern "C" {
  typedef struct FooEncoder FooEncoder;
  //...
}

foo_interface.h ：

typedef struct MyFooEncInst FooEncInst;

foo_interface.cc ：

#include "foo_interface.h"
#include "foo.h"
//...
struct MyFooEncInst {
  FooEncoder* encoder;
};
//...
MyFoo_Encode(FooEncInst* inst,...) {
//...
  if (d > inst->encoder->C) { // This is where I get the error
//...
}

$ b的地方$ b

foo_int32 是在另一个地方定义的。

foo_int32 is defined in another place.

推荐答案

您要在 FooEncoder 结构中寻找成员，该成员在 foo_interface.cc 文件中的任何位置都不可见。这看起来类似于 pimpl惯用语。

You're asking for a member in the FooEncoder struct which isn't visible anywhere in your foo_interface.cc file. This looks similar to a pimpl idiom.

要使您的代码了解 FooEncoder 的结构，您需要

In order to have your code aware of FooEncoder's structure you need to either

#include "foo_encoder.c"

在您的 foo_interface.cc 文件（我非常不喜欢这种解决方案，您也没有发布完整的代码），或者将结构定义移动到头文件中的其他位置，并包括该结构定义（推荐）。

in your foo_interface.cc file (I quite don't like this solution and you didn't post the full code either) or move your struct definition elsewhere in a header file and include that one (recommended).

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