Visual Basic .NET Language Introduction to Syntax Object Initializers
Example
-
Named Types
Dim someInstance As New SomeClass(argument) With { .Member1 = value1, .Member2 = value2 '... }Is equivalent to
Dim someInstance As New SomeClass(argument) someInstance.Member1 = value1 someInstance.Member2 = value2 '... -
Anonymous Types (Option Infer must be On)
Dim anonymousInstance = New With { .Member1 = value1, .Member2 = value2 '... }Although similar
anonymousInstancedoesn't have same type assomeInstanceMember name must be unique in the anonymous type, and can be taken from a variable or another object member name
Dim anonymousInstance = New With { value1, value2, foo.value3 '... } ' usage : anonymousInstance.value1 or anonymousInstance.value3Each member can be preceded by the
Keykeyword. Those members will beReadOnlyproperties, those without will be read/write propertiesDim anonymousInstance = New With { Key value1, .Member2 = value2, Key .Member3 = value3 '... }Two anonymous instance defined with the same members (name, type, presence of
Keyand order) will have the same anonymous type.Dim anon1 = New With { Key .Value = 10 } Dim anon2 = New With { Key .Value = 20 } anon1.GetType Is anon2.GetType ' TrueAnonymous types are structurally equatable. Two instance of the same anonymous types having at least one
Keyproperty with the sameKeyvalues will be equal. You have to useEqualsmethod to test it, using=won't compile andIswill compare the object reference.Dim anon1 = New With { Key .Name = "Foo", Key .Age = 10, .Salary = 0 } Dim anon2 = New With { Key .Name = "Bar", Key .Age = 20, .Salary = 0 } Dim anon3 = New With { Key .Name = "Foo", Key .Age = 10, .Salary = 10000 } anon1.Equals(anon2) ' False anon1.Equals(anon3) ' True although non-Key Salary isn't the same
Both Named and Anonymous types initializer can be nested and mixed
Dim anonymousInstance = New With {
value,
Key .someInstance = New SomeClass(argument) With {
.Member1 = value1,
.Member2 = value2
'...
}
'...
}
