c++ - 为什么编译器尝试在此代码片段中尝试将指针传递给引用，而不是指针？

我有5个文件：


ExecutionStrategyInterface.h
ExecutorInterface.h
TaskCollectionInterface.h
TaskExecutor.h
TaskExecutor.cpp。


TaskExecutor实现以下成员方法：

void TaskExecutor::execute(TaskCollectionInterface* tci, const ExecutionStrategyInterface& es) {
    es.execute(tci);
}

在编译时，编译器使用类型为指向引用（即：mylib::core::TaskCollectionInterface*&）的指针的参数来调用成员方法。

TaskExecutor.cpp: In member function ‘virtual void mylib::core::TaskExecutor::execute(mylib::core::TaskCollectionInterface*, const mylib::core::ExecutionStrategyInterface&)’:
TaskExecutor.cpp:16: error: no matching function for call to ‘mylib::core::ExecutionStrategyInterface::execute(mylib::core::TaskCollectionInterface*&) const’
./././ExecutionStrategyInterface.h:24: note: candidates are: virtual void mylib::core::ExecutionStrategyInterface::execute(TaskCollectionInterface*) const
make: *** [TaskExecutor.o] Error 1

有人能解释一下这里发生了什么吗？



类：

ExecutionStrategyInterface.h

#ifndef _EXECUTIONSTRATEGYINTERFACE_H_
#define _EXECUTIONSTRATEGYINTERFACE_H_

class TaskCollectionInterface;

namespace mylib { namespace core {

/**
 *  Interface for executing a strategy.
 */
class ExecutionStrategyInterface {
 public:
    /**
     * Executes a strategy
     */
    virtual void execute(TaskCollectionInterface* tci) const = 0;
};

}} // namespaces

#endif // _EXECUTIONSTRATEGYINTERFACE_H_

TaskCollectionInterface.h

#ifndef _TASKCOLLECTIONINTERFACE_H_
#define _TASKCOLLECTIONINTERFACE_H_

#include "./ExecutionStrategyInterface.h"

namespace mylib { namespace core {

/**
 *  Interface for a collection of tasks.
 */
class TaskCollectionInterface {
 public:
    ~TaskCollectionInterface();
};

}} // namespaces

#endif // _TASKCOLLECTIONINTERFACE_H_

ExecutorInterface.h

#ifndef _EXECUTORINTERFACE_H_
#define _EXECUTORINTERFACE_H_

class ExecutionStrategyInterface;
class TaskCollectionInterface;

#include "./ExecutionStrategyInterface.h"
#include "./TaskCollectionInterface.h"

namespace mylib { namespace core {

/**
 *  Interface for an executor.
 */
class ExecutorInterface {
 public:
    virtual void execute(TaskCollectionInterface* tci, const ExecutionStrategyInterface& es) = 0;
    ~ExecutorInterface();
};

}} // namespaces

#endif // _EXECUTORINTERFACE_H_

TaskExecutor.h

#ifndef _TASKEXECUTOR_H_
#define _TASKEXECUTOR_H_

#include "./ExecutorInterface.h"

class TaskCollectionInterface;
class ExecutionStrategyInterface;

namespace mylib { namespace core {

/**
 *  Task Runner.
 */
class TaskExecutor: public ExecutorInterface {
 public:
    virtual void execute(TaskCollectionInterface* tci, const ExecutionStrategyInterface& es) = 0;
};

}} // namespaces

#endif // _TASKEXECUTOR_H_

TaskExecutor.cpp

#include "./TaskExecutor.h"
#include "./ExecutionStrategyInterface.h"
#include "./TaskCollectionInterface.h"

namespace mylib { namespace core {

void TaskExecutor::execute(TaskCollectionInterface* tci, const ExecutionStrategyInterface& es) {
    es.execute(tci);
}

}} // namespaces

最佳答案

这是令人困惑的，因为您要在命名空间之外向前声明该类，因此最终将得到两个具有相同名称的不同类。您将需要这样的东西：

namespace mylib {
  namespace core {
    class TaskCollectionInterface;
    class ExecutionStrategyInterface {
      .
      .
      .
    };
  }
}

现在，您的执行方法将采用:: TaskCollectionInterface的指针，而不是mylib :: core :: TaskCollectionInterface的指针。