CLS Compliant WaitForSingleObject

Maartens recent blog post highlighted an issue with the current SDF implementation of Core.WaitForSingleObject when used from VB.NET since this method was not CLS Compliant and used unsigned integer types for both parameters and return type. Because of the values used by this function its very easy to convert it to be CLS compliant, so from the next release you’ll be able to call it just as easily from both C# and VB. The method only accepts a timeout value up to 0x7fffffff which incidently is the maximum positive value for an Int32. The exception to this is a special constant passed when you want to wait indefinately on a handle – 0xffffffff which just happens to be -1 when interpreted as a signed integer. The same transformations are posible on the Wait enumeration which is the return type for the method. The amended code is already up on the online source browser. Therefore to wait with a 1s timeout on a handle in a loop you can now do this from VB:-

While WaitForSingleObject(myWin32Event, 1000) <> Wait.Object

            ‘do stuff here

End While

By Peter Foot

Microsoft Windows Development MVP