I’ve done quite a bit of VB.NET maintenance lately.
Most of that code was riddled with CType, both for conversions and casts. Quite a bit code had Option Explicit and Option Strict Off. A lot of those CType constructions had empty Try / Catch / End Try blocks around them.
Those empty catch blocks are a code smell. They pretend to be able to survive any exceptional disaster, but in practice you can’t. You have to indicate what kinds of disasters you can handle, for instance if a meteorite hits your data center (thanks George Stocker).
Turning off Option Strict can be OK under many circumstances (the default is off), but having Option Explicit off is usually a code smell as well, just like On Error Resume Next (which was also in plenty of the source code).
I do understand a lot of VB.NET source comes from people having programmed in VB 6, VBScript or VBA for a long time where those constructs were more common. But writing code in the 21st century is much more about writing code that you can prove to be right. Having proper error handling and compiler type checking is a big part of that.
It pays to go with the idiom, for example read the good and bad ways of vb.net – Safest way to check for integer.
Back to CType: basically you have do distinguish between conversions and casts. The reason is that when you know it will be a form of cast, CType is way to expensive. And if you know you will be doing conversions, than casting is not what you want.
The Wiert Corner - irregular stream of stuff 