VB.NET equivalent for the C# 7 is operator declaration pattern

Question

Is there a VB.NET equivalent to the C# 7 is operator declaration pattern? Note in particular the bmp in the following code sample:

public void MyMethod(Object obj)
{
    if (obj is Bitmap bmp)
    {
        // ...
    }
}

Or the short pattern matching syntax with is is exclusive to C#?

EDIT:

I already know these syntaxes:

    If TypeOf obj Is Bitmap Then
        Dim bmp As Bitmap = obj
        ' ...
    End If

or

    Dim bmp As Bitmap = TryCast(obj, Bitmap)
    If bmp IsNot Nothing Then
        ' ...
    End If

What I want to know is whether there is something even shorter, like that new C#7 is operator declaration pattern...

Thank you very much.

Sorry, I didn't asked clearly from begginning. Please see edit. — VBobCat, Nov 26 '17 at 11:23
I think there is no. The team of vb.net [chose not to run after the incessant improvements of C#](https://blogs.msdn.microsoft.com/vbteam/2017/02/01/digging-deeper-into-the-visual-basic-language-strategy/). — dovid, Nov 26 '17 at 11:49
https://github.com/dotnet/vblang/issues/124 https://github.com/dotnet/vblang/issues/172 — dovid, Nov 26 '17 at 12:05
This trick isn't the cast. The trick is the variable declaration in the same line of code. — Joel Coehoorn, Feb 15 '18 at 05:11
There are now a few related open proposals on the vblang Github repo; see [here](https://github.com/dotnet/vblang/issues/337) and [here](https://github.com/dotnet/vblang/issues/367) among others. — Zev Spitz, Dec 13 '19 at 08:00

score 3 · Accepted Answer · answered Apr 04 '18 at 16:14

3

Currently, no. If you want to implement this, you'll have to use some of the longer formats you already mention in your question.

The C# and VB languages don't always have equivalent features.

answered Apr 04 '18 at 16:14

score -1 · Answer 2 · answered May 14 '19 at 15:38

-1

Use a one line if

If obj is bitmap Then Dim bmp = obj

or use an in-line if (this is the if function)

Dim bmp = If(obj is bitmap, obj, Nothing)

Not quite pattern-matching per se, but is does the same thing.

Couldn't you do it this way in C#:

var bmp = obj is bitmap ? obj : nothing;

answered May 14 '19 at 15:38

John Grabauskas

2

As far as my testing goes, this would miss object typing and return Object type. – bkqc Dec 17 '20 at 19:07
`obj is bitmap` is illegal. – NetMage May 10 '21 at 21:05
Don't do any of these. Use the standard (and already mentioned) `Dim bmp As Bitmap = TryCast(obj, Bitmap)`. If `Option Strict` is ON and `Option Infer` is OFF, then `Dim` acts like c#'s `var, so can shorten this to `Dim bmp = TryCast(obj, Bitmap)`. – ToolmakerSteve Aug 03 '21 at 10:18

2 Answers2