Question

我有一个带有枚举值作为参数的类。它有一个成员m_ConsistencyErrors，它是std::set。我想根据枚举参数的值在构造时设置此成员的类型。

如果TestType值为MSG123_CONSISTENCY_TEST，我希望m_ConsistencyErrors的类型为std::set<EnMsg123Param>

如果TestType值为MSG5_CONSISTENCY_TEST，我希望m_ConsistencyErrors的类型为std::set<EnMsg5Param>

有没有一种干净的方法来实现这一目标，或者我应该找到其他解决方案。

class CMsgConsistencyTest // : public CTestBase  // left out for simplicity
{
    enum EnTests
    {
        MSG123_CONSISTENCY_TEST,
        MSG5_CONSISTENCY_TEST,
    };
    enum EnMsg123Param
    {
        Msg123_1,
        Msg123_2
    };
    enum EnMsg5Param
    {
        Msg5_1,
        Msg5_2
    };

public:
    CMsgConsistencyTest(const EnTests TestType) //  : CTestBase(TestType)  // left out for simplicity
    {
        if (TestType == MSG123_CONSISTENCY_TEST)
        {
            ParameterType = EnMsg123Param;  // pseudo code
        }
        else if (TestType == MSG5_CONSISTENCY_TEST)
        {
            ParameterType = EnMsg5Param;  // pseudo code
        }
    }

private:
    template<typename ParameterType>
    std::set<ParameterType> m_ConsistencyErrors;
};

Answer 1

您不能这样做，当您使用 CMsgConsistencyTest 及其成员访问m_ConsistencyErrors

时，必须始终知道 ParameterType

为此， CMsgConsistencyTest 可以是模板类，例如

#include <set>

enum EnMsg123Param
{
  Msg123_1,
  Msg123_2,
};

enum EnMsg5Param
{
  Msg5_1,
  Msg5_2,
  Msg5_3,
};

template<typename ParameterType>
class CMsgConsistencyTest // : public CTestBase  // left out for simplicity
{
  public:
    // ...
  private:
    std::set<ParameterType> m_ConsistencyErrors;
};

// and for instance

CMsgConsistencyTest<EnMsg123Param> A;
CMsgConsistencyTest<EnMsg5Param> B;

否则，您可能需要做一些丑陋的，灾难性的事情以及类似“ non C ++”的事情：

   CMsgConsistencyTest(const EnTests TestType) //  : CTestBase(TestType)  // left out for simplicity
    {
        if (TestType == MSG123_CONSISTENCY_TEST)
        {
            m_ConsistencyErrors = new set<EnMsg123Param>;
        }
        else if (TestType == MSG5_CONSISTENCY_TEST)
        {
            m_ConsistencyErrors = new set<EnMsg5Param>;
        }
        // else ?
        // probably need to save TestType etc
    }

private:
    void * m_ConsistencyErrors;

根据参数在构造函数中设置成员数据类型

1 个答案: