vb.net - LINQ 中的 Equals 和 = 有什么区别？

Question

有什么区别等于 和 = 在LINQ？

Dim list As List(Of Foo) = (From a As Foo In FooList _
Join b As Bar In BarList _
On a.Something = b.Something _
Select a).ToList()

相对

Dim list As List(Of Foo) = (From a As Foo In FooList _
Join b As Bar In BarList _
On a.Something Equals b.Something _
Select a).ToList()

Answer 1

来自 The Moth谁引用了马特沃伦

"The reason C# has the word ‘equals’ instead of the ‘==’ operator was to make it clear that the ‘on’ clause needs you to supply two separate expressions that are compared for equality not a single predicate expression. The from-join pattern maps to the Enumerable.Join() standard query operator that specifies two separate delegates that are used to compute values that can then be compared. It needs them as separate delegates in order to build a lookup table with one and probe into the lookup table with the other. A full query processor like SQL is free to examine a single predicate expression and choose how it is going to process it. Yet, to make LINQ operate similar to SQL would require that the join condition be always specified as an expression tree, a significant overhead for the simple in-memory object case."

编辑

文章后面。

更新:来自 Visual Basic 团队的 Vladimir Sadov 告诉我，VB 也出于几乎相同的原因使用 Equals。