Question

Why is this working as expected:

list.ForEach(sub(x) x.Name = "New Name")

But this isn’t:

list.ForEach(function(x) x.Name = "New Name")

Anyone else confused?

Answer 1

List(Of T).ForEach takes as an argument an Action (Sub) that doesn’t return a value not a Func (Function) that does return a value.

In VB the = sign is ambiguous. It can either be used for comparison or assignment. As a result to disambiguate the statement, x.Name = "New Name" the team used the indicator Sub or Function to identify if this is a comparison or assignment. In the case of Sub(x) x.Name = "New Name", you are performing an assignment, or set the value of x’s Name parameter to “New Name”. In the case of Function(x) x.Name = New "Name" you are doing a comparison and returning if the Name parameter of x is the same as “New Name”. As a result, you have to be careful when you use Sub and Function.