Question

Enum.GetValues（）是否使用反射？

我认为不会，因为在编译时它应该能够获取可能值的列表并存储它们。但是我不知道那是不是真的。

Answer 1

我认为应该。下面是完成这项工作的代码

    // This will return enumValues and enumNames sorted by the values.
    private void GetEnumData(out string[] enumNames, out Array enumValues)
    {
        Contract.Ensures(Contract.ValueAtReturn<String[]>(out enumNames) != null);
        Contract.Ensures(Contract.ValueAtReturn<Array>(out enumValues) != null);

        FieldInfo[] flds = GetFields(BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Static);

        object[] values = new object[flds.Length];
        string[] names = new string[flds.Length];

        for (int i = 0; i < flds.Length; i++)
        {
            names[i] = flds[i].Name;
            values[i] = flds[i].GetRawConstantValue();
        }

        // Insertion Sort these values in ascending order.
        // We use this O(n^2) algorithm, but it turns out that most of the time the elements are already in sorted order and
        // the common case performance will be faster than quick sorting this.
        IComparer comparer = Comparer.Default;
        for (int i = 1; i < values.Length; i++)
        {
            int j = i;
            string tempStr = names[i];
            object val = values[i];
            bool exchanged = false;

            // Since the elements are sorted we only need to do one comparision, we keep the check for j inside the loop.
            while (comparer.Compare(values[j - 1], val) > 0)
            {
                names[j] = names[j - 1];
                values[j] = values[j - 1];
                j--;
                exchanged = true;
                if (j == 0)
                    break;
            }

            if (exchanged)
            {
                names[j] = tempStr;
                values[j] = val;
            }
        }

        enumNames = names;
        enumValues = values;
    }

请注意 FieldInfo [] flds = GetFields（BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Static）; 行。它真的看起来像反射方法。 GetFields方法是抽象的

 abstract public FieldInfo[] GetFields(BindingFlags bindingAttr);

所以我不确定如何为枚举实现它。

Enum.GetValues（）是否使用反射？

1 个答案: