Option Strict On does not cause compilation error

[Justin]

I have set Option Strict On
I also have Enum AssemblyLineSta tus As Integer
My question is how come there is no compilation error when I compile
following code?

If CInt(ddlStatus. SelectedItem.Va lue) = AssemblyLineSta tus.Client Then
' do whatever
End If

Shouldn't this cause a compilation error? I know in C#, you have to
explicitly either convert enumation to int or int to enumuation.

Just curious.
Thanks

[Larry Lard]

Re: Option Strict On does not cause compilation error


Justin wrote:[color=blue]
> I have set Option Strict On
> I also have Enum AssemblyLineSta tus As Integer
> My question is how come there is no compilation error when I compile
> following code?
>
> If CInt(ddlStatus. SelectedItem.Va lue) = AssemblyLineSta tus.Client Then
> ' do whatever
> End If
>
> Shouldn't this cause a compilation error? I know in C#, you have to
> explicitly either convert enumation to int or int to enumuation.[/color]

VB is different, and less strict here. In VB, **a widening conversion
(essentially, one guaranteed not to lose information) can always occur
implicitly**. Conversion from an enum value to the enum's underlying
type is obviously widening, so in the above code,
AssemblyLineSta tus.Client gets widened to its Integer value.

In C#, on the other hand, there is no such general rule of implicitness
for widening conversions, and the set of implicit conversions is hence
much smaller. All conversions between enum types and numeric types -
even an enum's underlying type - must be explicit.

VB.NET is stricter than VB6, but it still isn't as strict as C#.

--
Larry Lard
Replies to group please

[Phill W.]

Re: Option Strict On does not cause compilation error

Justin wrote:[color=blue]
> I have set Option Strict On[/color]

Good Start ...
[color=blue]
> I also have Enum AssemblyLineSta tus As Integer[/color]
....[color=blue]
> If CInt(ddlStatus. SelectedItem.Va lue) = AssemblyLineSta tus.Client Then
> ' do whatever
> End If
>
> Shouldn't this cause a compilation error?[/color]

CInt() returns an Integer and all Enums are defined as Integer.
I suspect VB sees Enum-to-Integer as a Widening Conversion, much like
Short-to-Integer.
[color=blue]
> I know in C#, you have to explicitly either convert[/color]

If you want to do the comparsion "as" the Enumeration, try this

' Throws ArgumentExcepti on (IIRC) for invalid values
Dim eValue as AssemblyLineSta tus _
= CType(ddlStatus .SelectedItem.V alue _
, AssemblyLineSta tus)

If eValue = AssemblyLineSta tus.Client Then
' do whatever
End If

HTH,
Phill W.