無法從LINQ的字典

Question

當我嘗試使用.Count之間的（）在VB.NET以下

Dim data = New Dictionary(Of String, Integer) 
data.Count(Function(x) x.Value > 0) 'Compile-time error! 

我得到這個編譯錯誤與.Net Fiddle：

Too many arguments to 'Public Overloads ReadOnly Property Count As Integer'

的Visual Studio給我這個錯誤：

'Public ReadOnly Property Count As Integer' has no parameters and its return type cannot be indexed.

下面做工作，但：

Enumerable.Where(data, Function(x) x.Value > 0).Count() 'Works! 
data.Where(Function(x) x.Value > 0).Count() 'Works! 

它似乎沒有找到正確的過載。

奇怪的是，夠本了C＃版本Visual Studio中工作得很好（但在.NET小提琴失敗 - 奇......這是怎麼回事？）：

var data = new Dictionary<string, int>(); 
data.Count(x => x.Value > 0); 

---

什麼是正確的方法對字典使用LINQ版本.Count()with a predicate？

Answer 1

當名稱發生衝突時，您需要使用AsEnumerable()（請參閱備註部分）來獲取擴展方法。

data.AsEnumerable().Count(Function(x) x.Value > 0) 

Answer 2

然而，有一個原因是在VB.NET它的工作原理不同於C#：

When an in-scope instance method has a signature that is compatible with the arguments of a calling statement, the instance method is chosen in preference to any extension method. The instance method has precedence even if the extension method is a better match.

甚至

The situation is simpler with properties: if an extension method has the same name as a property of the class it extends, the extension method is not visible and cannot be accessed.

一個Dictionary(Of TKey, TValue) Class已經有一個屬性名爲Count所以Count擴展隱。

Extension Methods (Visual Basic) > Extension Methods, Instance Methods, and Properties

我會跳過如何，部分是因爲@馬克已經answerd說。