a question on error-handling in API

qiangyu

Hi,

for a target freshly created, the attempt to read the target's robotconfiguration property arises an "No configuration" error, and goes to my error-handling code. Is there any way to detect this so that it won't go to the errorr-handling code? I tried IsEmpty, and a few other Is.. functions in vB in vain.

Thank you very much.

John

PerSvensson

Hi
What you could do is something like this

On Error Resume Next

Dim t as Target
Set t = ActiveStation.Targets("your target")
if t.RobotConfiguration.Cf1 = null then
  ' Do the error handling
End If

qiangyu

Hi, thank you very much for your reply.

I may not make myself understood. My code would be like this:

On Error Goto HandleError

...

If t.RobotConfiguration.cf1 = null Then

... do stuff ...

Else 

... do other stuff ...

End If

...

HandleError:

... Error handling code ...

 

When executing the "If t.RobotConfiguration.cf1 = null Then", it immediately goes to the error handling routine below. I have also tried " if IsNull(t.RobotConfiguration) then ", and the same thing happened.

It looks like any reference to t.RobotConfiguration in any fashion leads to an error, while I am trying to find a API or VB function to acheive the logic structure similar to the above code. 

 

PerSvensson

Hi
The difference is that instead of jumping to the error handler you define that if there is an error you continue with the next instruction

On Error Resume Next

instead of

On Error Goto HandleError

You can also turn off or change how the error handler should behave during program execution.

qiangyu

Got it. Thank you very much.