Question

I want to know if it’s possible to implement a Do Loop with an extension function.

Here’s my non-working code:

  <System.Runtime.CompilerServices.Extension()> _
  Public Sub DoUntil(condition As Func(Of Boolean), action As Action)
    Do Until condition
      action()
    Loop
  End Sub

So it could be called like:

   DoUntil(Function() Finished = True, Sub()
 x = x + 1
If IsPrime(x) Then
  Finished = True
)

But I get error: Value of type ‘System.Func(Of Boolean)’ cannot be converted to ‘Boolean’

Thanks.

Answer 1

Assuming you already have this (C#, sorry, I’m not very proficient with VB):

//Table name we're looking for
var LookingFor = "Foo";
//Tablenamess returned by some function (in this case some array)
var Foos = new[] { "Bar", "Foobar", "Foo_w00t", "Foo1", "foo7", "SomeFoo", "Foo_3", "Foo4", "F00", "Foo" };

Getting the count is easy:

//Look for "XXX[0-9]+" where XXX is the (case insensitive for demonstration purposes) tablename
Regex r = new Regex(string.Format("^{0}[0-9]*$", Regex.Escape(LookingFor)), RegexOptions.IgnoreCase);
var count = Foos.Count(x => r.IsMatch(x));

This returns 4 (Foo1, foo7, Foo14 and Foo).