使用自己的KeyValuePair <tkey，tvalue =“”>为字典实现IEnumrable <t>

Question

我的问题之后 Problem with implementation own version of KeyValuePair<TKey, TValue> 现在我不会更改课程代码

   public class VectorType<TKey, TValue> : IEnumerable<KeyValuePair<TKey, TValue>>
    {
        string variableName;
        Dictionary<TKey, TValue> paramteresList;

        public VectorType(string variableName)
        {
            this.variableName = variableName;
            paramteresList = new Dictionary<TKey, TValue>();
        }

        public void Add(TKey parameterName, TValue parametereValue)
        {
            paramteresList.Add(parameterName, parametereValue);
        }

        public int NumberOfParameters
        {
            get { return paramteresList.Count; }
        }

        public string VariableName
        {
            get { return variableName; }
        }

        IEnumerator IEnumerable.GetEnumerator()
        {
            return ((IEnumerable)paramteresList).GetEnumerator();
        }

        IEnumerator<KeyValuePair<TKey, TValue>> IEnumerable<KeyValuePair<TKey, TValue>>.GetEnumerator()
        {
            return paramteresList.GetEnumerator();
        }
    }

将我自己的KeyValuePair实现用作

public struct ParameterNameKeyValuePair<TParameterNameKey, TValue>
{
    private TParameterNameKey key;
    private TValue value;

    public ParameterNameKeyValuePair(TParameterNameKey key, TValue value)
    {
        this.key = key;
        this.value = value;
    }

    public TParameterNameKey Key
    {
        get { return key; }
    }

    public TValue Value
    {
        get { return value; }
    }
}

如果我将KeyValuePair更改为ParameterNameKeyValuePair我有

    public class VectorType<TParameterNameKey, TValue> : IEnumerable<ParameterNameKeyValuePair<TParameterNameKey, TValue>>
    {
        string variableName;
        Dictionary<TParameterNameKey, TValue> paramteresList;

        public VectorType(string variableName)
        {
            this.variableName = variableName;
            paramteresList = new Dictionary<TParameterNameKey, TValue>();
        }

        public void Add(TParameterNameKey parameterName, TValue parametereValue)
        {
            paramteresList.Add(parameterName, parametereValue);
        }

        public int NumberOfParameters
        {
            get { return paramteresList.Count; }
        }

        public string VariableName
        {
            get { return variableName; }
        }

        IEnumerator IEnumerable.GetEnumerator()
        {
            return ((IEnumerable)paramteresList).GetEnumerator();
        }

        IEnumerator<ParameterNameKeyValuePair<TParameterNameKey, TValue>> IEnumerable<ParameterNameKeyValuePair<TParameterNameKey, TValue>>.GetEnumerator()
        {
            return paramteresList.GetEnumerator();
        }
    }

，我在编译时出错：无法隐式转换类型 从'System.Collections.Generic.Dictionary.Enumerator'到'System.Collections.Generic.IEnumerator>'

        IEnumerator<ParameterNameKeyValuePair<TParameterNameKey, TValue>> IEnumerable<ParameterNameKeyValuePair<TParameterNameKey, TValue>>.GetEnumerator()
        {
            return paramteresList.GetEnumerator();
        }

我只将KeyValuePair更改为ParameterNameKeyValuePair。我有这个错误吗？第二个问题，像在我的情况下ParameterNameKeyValuePair那样实现自己的KeyValuePair是安全的吗？