vb.net - 通过属性分配给结构变量

Question

我有以下内容

Public Structure Foo
   dim i as integer
End Structure

Public Class Bar

Public Property MyFoo as Foo
Get
   return Foo
End Get
Set(ByVal value as Foo)
   foo  = value
End Set

dim foo as Foo    
End Class

Public Class Other

   Public Sub SomeFunc()    
     dim B as New Bar()    
     B.MyFoo = new Foo()    
     B.MyFoo.i = 14 'Expression is a value and therefore cannot be the target of an assignment ???    
   End Sub
End Class

我的问题是，为什么我不能通过 Bar 类中的属性分配给 i？我做错了什么？

Answer 1

找到答案here ，它说了以下内容:

' Assume this code runs inside Form1.
Dim exitButton As New System.Windows.Forms.Button()
exitButton.Text = "Exit this form"
exitButton.Location.X = 140
' The preceding line is an ERROR because of no storage for Location.

The last statement of the preceding example fails because it creates only a temporary allocation for the Point structure returned by the Location property. A structure is a value type, and the temporary structure is not retained after the statement runs. The problem is resolved by declaring and using a variable for Location, which creates a more permanent allocation for the Point structure. The following example shows code that can replace the last statement of the preceding example.

这是因为结构只是一个临时变量。因此，解决方案是创建一个您需要的新结构，为其分配所有内部变量，然后将该结构分配给类的结构属性。