界面IQBBase
是最接近您正在寻找的东西。QBFC 中的大部分内容都派生自IQBase
,包括所有查询类型和所有返回类型。使用IQBBase
引用和 .NET 泛型可以创建一个框架来处理查询结果。
更新:下面的迭代器示例现在作为 QBFC 的 Zombie 库的一部分提供,您可以从 github 获取。
例如,下面是一个将 RetList 类型和 Ret 类型作为参数的通用迭代器:
/// <summary>
/// This generic class simplifies and standardizes iteration syntax
/// for QBFC lists. Using this class we can use the foreach keyword
/// to iterate across all items in a list.
/// </summary>
/// <typeparam name="L">The type of the list, for example IBillRetList</typeparam>
/// <typeparam name="D">The type of the item, for example IBillRet</typeparam>
public class QBFCIterator<L, D>:IEnumerable<D> where L : class, IQBBase
{
private L m_List;
/// <summary>
/// This constructor can be used for response list items or for sub-lists that are properties
/// on other QBFC objects.
/// </summary>
/// <param name="lst">The sub-list</param>
public QBFCIterator(IQBBase lst)
{
m_List = lst as L;
if (m_List == null && lst != null)
{
throw new Exception("iterator type mismatch");
}
}
public bool IsEmpty
{
get
{
if (m_List == null)
{
return true;
}
else
{
return Count == 0;
}
}
}
/// <summary>
/// An efficient alternative to the Count() function
/// </summary>
public int EntityCount
{
get { return Count; }
}
public D GetFirstItem()
{
if (IsEmpty)
{
throw new Exception("Cannot retrieve item from empty list");
}
else
{
return GetAt(0);
}
}
#region Late-bound properties
//
// Since .NET requires that all methods invoked on a parameterized type
// must compile based solely on interface constraints, we must use late
// binding to access the count property and GetAt methods. This may have
// an impact on performance and could conceivably cause run time errors
// with incorrect type parameters.
//
private int Count
{
get
{
if (m_List == null)
{
return 0;
}
else
{
Type t = m_List.GetType();
return (int)t.InvokeMember("Count",
System.Reflection.BindingFlags.GetProperty, null, m_List, null);
}
}
}
private D GetAt(int idx)
{
Type t = m_List.GetType();
return (D)t.InvokeMember("GetAt",
System.Reflection.BindingFlags.InvokeMethod, null, m_List, new Object[] { idx });
}
#endregion
#region IEnumerable<D> Members
public IEnumerator<D> GetEnumerator()
{
if (m_List != null)
{
for (int idx = 0; idx < Count; idx++)
{
yield return GetAt(idx);
}
}
}
#endregion
#region IEnumerable Members
System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
{
if (m_List != null)
{
for (int idx = 0; idx < Count; idx++)
{
yield return GetAt(idx);
}
}
}
#endregion
}