Creating a list of Anonymous Type in VB
Since the type is anonymous, you must use generic and type-inference.
The best way is to introduce a generic function that creates an empty collection from a prototype object.
Module Module1
Sub Main()
Dim dsResource = New With {.Name = "Foo"}
Dim List = dsResource.CreateTypedList
End Sub
<System.Runtime.CompilerServices.Extension()> _
Function CreateTypedList(Of T)(ByVal Prototype As T) As List(Of T)
Return New List(Of T)()
End Function
End Module
How about a single line construct like this?
Dim yourList = {(New With {.Name="", .Age=0})}.Take(0).ToList
Here's a handy method for creating a list of an anonymous type from a single anonymous type.
Public Function CreateListFromSingle(Of T)(ByVal p1 As T) As List(Of T)
Dim list As New List(Of T)
list.Add(p1)
return List
End Function
Now you can just do the following
Dim list = CreateListFromSingle(dsResource)
EDIT OP wanted a way to create the list before creating an element.
There are 2 ways to do this. You can use the following code to create an empty list. It borders on hacky because you are passing parameters you don't ever intend to use but it works.
Public Function CreateEmptyList(Of T)(ByVal unused As T) As List(Of T)
Return New List(Of T)()
End Function
Dim x = CreateEmptyList(New With { .Name = String.Empty, .ID = 42 })
Here is how to do it inline using casting by example (without creating a second function):
Sub Main()
Dim x = New With {.Name = "Bob", .Number = 8675309}
Dim xList = {x}.ToList()
End Sub
(based on c# version posted here )
Essentially you create the anonymous type, put it in an array ( {x} ) then use the array's .ToList() method to get a list.