iif and type inference

[Maurizio Colucci]

Hello,

Is there a way in VB.NET to do something like

dim myInt = if foo() then bar(3) else 4

and have the compiler infer that myInt is an Integer, since bar()
returns an integer and 4 is an integer?

Thanks a lot for any info.

Maurizio

 

[Stanimir Stoyanov]

No, there is not a short equivalent of if-else in VB.NET as there is in C#
(condition ? true : false) but if you are sure that both statements return
an object of the same type, you can cast the result of IIf: CInt(IIf(foo(),
bar(3), 4)) in your case.

Best Regards,
Stanimir Stoyanov | www.stoyanoff.info

 

[Martin H.]

Hello Maurizio,

Since the code is not sooo difficult - why don't you just give it a try?

Best regards,

Martin

 

[Maurizio Colucci]

Hello Maurizio,

Since the code is not sooo difficult - why don't you just give it a try?

I'm sorry, I don't think I understand that you mean.

Maurizio

 

[Maurizio Colucci]

No, there is not a short equivalent of if-else in VB.NET as there is in C#
(condition ? true : false) but if you are sure that both statements return
an object of the same type, you can cast the result of IIf: CInt(IIf(foo(),
bar(3), 4)) in your case.

Thank you, I was afraid that was the only way. It also does not use
lazy evaluation.

Maurizio

 

[Nick Hall]

No, there is not a short equivalent of if-else in VB.NET as there is in C#
(condition ? true : false) but if you are sure that both statements return
an object of the same type, you can cast the result of IIf:
CInt(IIf(foo(), bar(3), 4)) in your case.

Note that if you're using VS 2008 this is no longer the case. The If
operator has been added which gives you type-safety and short circuiting
behaviour just like C#'s ? operator. Using the OP's example the code would
become: -

Dim myInt = If(foo(), bar(3), 4)

Also note that as this is a compiler feature you do not have to be
targetting the 3.5 version of the framework in order to use it.

Hope this helps,

Nick Hall

 

[Maurizio Colucci]

Which version ? If VB 2008, you could use the new If function :

        Dim myInt = If(foo(), bar(3), 4)

That's great! Exactly what I was hoping for. Thanks a lot Patrice.

M

 

[Maurizio Colucci]

Thank you Nick. That's exactly what I was hoping for.

Maurizio