ICollection/ICollection< T>歧义问题 [英] ICollection / ICollection<T> ambiguity problem

问题描述

只是想对语法句法糖进行简单扩展:

Just want to make simple extension for syntactic sygar :

public static bool IsNotEmpty(this ICollection obj)
{
    return ((obj != null)
        && (obj.Count > 0));
}

public static bool IsNotEmpty<T>(this ICollection<T> obj)
{
    return ((obj != null)
        && (obj.Count > 0));
}

当我使用某些集合时，它可以完美工作，但是当我使用其他集合时，我可以得到

It works perfectly when I work with some collections, but when working with others I get

以下方法或属性: 'PowerOn.ExtensionsBasic.IsNotEmpty(System.Collections.IList)' 和 'PowerOn.ExtensionsBasic.IsNotEmpty(System.Collections.Generic.ICollection)'

The call is ambiguous between the following methods or properties: 'PowerOn.ExtensionsBasic.IsNotEmpty(System.Collections.IList)' and 'PowerOn.ExtensionsBasic.IsNotEmpty(System.Collections.Generic.ICollection)'

此问题是否有任何规范解决方案?

Is there any canonical solution to this problem ?

不，我不想在调用此方法之前执行强制转换；)

No, I don't want to perform a cast before calling this method ;)

推荐答案

解决歧义的最佳方法:为所有常见的非通用ICollection类定义一个重载. 这意味着自定义ICollection将不兼容，但是随着泛型成为规范，这没什么大不了的.

My best way to solve the ambiguity : define an overload for all common non-generic ICollection classes. That means custom ICollection won't be compatible, but it's no big deal as generics are becoming the norme.

这是整个代码:

/// <summary>
/// Check the given array is empty or not
/// </summary>
public static bool IsNotEmpty(this Array obj)
{
    return ((obj != null)
        && (obj.Length > 0));
}
/// <summary>
/// Check the given ArrayList is empty or not
/// </summary>
public static bool IsNotEmpty(this ArrayList obj)
{
    return ((obj != null)
        && (obj.Count > 0));
}
/// <summary>
/// Check the given BitArray is empty or not
/// </summary>
public static bool IsNotEmpty(this BitArray obj)
{
    return ((obj != null)
        && (obj.Count > 0));
}
/// <summary>
/// Check the given CollectionBase is empty or not
/// </summary>
public static bool IsNotEmpty(this CollectionBase obj)
{
    return ((obj != null)
        && (obj.Count > 0));
}
/// <summary>
/// Check the given DictionaryBase is empty or not
/// </summary>
public static bool IsNotEmpty(this DictionaryBase obj)
{
    return ((obj != null)
        && (obj.Count > 0));
}
/// <summary>
/// Check the given Hashtable is empty or not
/// </summary>
public static bool IsNotEmpty(this Hashtable obj)
{
    return ((obj != null)
        && (obj.Count > 0));
}
/// <summary>
/// Check the given Queue is empty or not
/// </summary>
public static bool IsNotEmpty(this Queue obj)
{
    return ((obj != null)
        && (obj.Count > 0));
}
/// <summary>
/// Check the given ReadOnlyCollectionBase is empty or not
/// </summary>
public static bool IsNotEmpty(this ReadOnlyCollectionBase obj)
{
    return ((obj != null)
        && (obj.Count > 0));
}
/// <summary>
/// Check the given SortedList is empty or not
/// </summary>
public static bool IsNotEmpty(this SortedList obj)
{
    return ((obj != null)
        && (obj.Count > 0));
}
/// <summary>
/// Check the given Stack is empty or not
/// </summary>
public static bool IsNotEmpty(this Stack obj)
{
    return ((obj != null)
        && (obj.Count > 0));
}
/// <summary>
/// Check the given generic is empty or not
/// </summary>
public static bool IsNotEmpty<T>(this ICollection<T> obj)
{
    return ((obj != null)
        && (obj.Count > 0));
}

请注意，我不希望它在IEnumerable<T>上运行，因为Count()是一种在使用Linq-to-Entity或Linq-to-SQL时可以触发数据库请求的方法.

Note that I did not want it to work on IEnumerable<T>, because Count() is a method that can trigger a database request if you are working with Linq-to-Entity or Linq-to-SQL.

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