Resume Stuff in VBA error handling
( On Error Resume Next )
Resume and Resume Next and Resume LabelOrLineNumber
It turns out that the 3 resume statements are similar, but that the On Error Resume Next is, while having some similarities, not a simple intuitive derivative of the more fundamental resumes.
Often the word resume will generally mean a restart or somehow continuing.. In VBA, Generally, anything using the word Resume has the effect of putting VBA into a state as it had been previously. An important part of anything being done with anything using Resume will be therefore to stop the exceptional state. Often this is referred to as clearing the exception. That is the important difference between the two main error handling statements: For On Error GoTo LabelOrLineNumber we still have an exceptionally aroused erection state ****
Once again as it is important and is not intuitive: In VBA anything using the word Resume will usually clear the exception.
On Error GoTo LabelOrLineNumber does not clear the exception.
I don't know if the following derived way of looking at the resumes and then finally getting to On Error Resume Next , is anything like how VBA might do it, but it might be, and I felt like a change in the way of explaining.
The goal is to produce something pretty dangerous and very unwise to do. This is often a feature generally of Microsoft Software, and as application programmers we have access to the tools to help us break things.
We want a "blanket" error handler that just tells VBA to carry on at the next line after any error as if nothing had happened.
From the previous discussions we think that an error does automatically kick in the exception software, but we have a chance to pseudo hang a hook on the chain of events to call back / Hold back procedures as this is possible generally in any Windows / Visual basic coding environment…
I will assume that in the case of a On Error Resume Next I might want to know what error had occurred. ( In the first instance, if the exception is cleared, then so is the information in the Err object, so I will need to make some extra coding to get that info available again in Err. This will help us demo more aspects of error handling )
( **(On Error Resume Next )
I might be inclined to call this the second user definable types of error handling statement and put this alongside the one of the Error Handling statements we already comsidered, On Error GoTo LabelOrLineNumber. One reason why I do this is that it does not seem to logically follow what might be expected based on the Resume Next, specifically,
On Error Resume Next does not seem to clear the registers in object Err
, but
Resume Next does not seem to clear the registers in object Err
Strange. This seemingly jumbled up logic may be one reason why the subject is not always understood fully )
I believe the Resume is either the most , or pen ultimately most , fundamental step in what we are trying to achieve. It is interesting that one of the less common error handling statements , On Error GoTo -1 , has little earlier documentation, so I am not sure if it may be a derivative from Resume , which seems to have a more extensive documentation history.
Resume ( and Resume Next and Resume LabelOrLineNumber) will syntax fail ( error themselves in runtime ) if no error has occurred.
It is a good time perhaps to explain briefly the remaining error things, as they may be relevant to the final bad thing to have, On Error Resume Next , which will let us charge through like a blind dumb Bull in a china shop causing errors, breaking things un hindered throughout any code progression.
On Error GoTo -1
This clears the exception. This can be passed by a running code when the code is hunged embedded in the exception software running in the aroused erection, or in the normal un aroused code run. In the latter case , of "normal" code running, it has no effect. That is reasonable. In the exception case, it will effectively make the code continue in normal VBA mode in the current state using current back up exception Buffer data info retrieval.
I do not know if there is any reasoning behind the use of -1. Certainly it confuses most people. It does not confuse me, it makes a strange logic… I often put a fictitious '-1 on the wrong side of Sub at the top. As far as errors are concerned I think of it as meaning that the code is pseudo at its non started state, in which case no exception can have been raised. But that is not a perfect analogy, since we do not restart the coding, but rather just carry on, “back in the real world”, at a point just after where the _ On Error GoTo -1 is. _ This is like the end of the diversion, where the coding between
_ [ where the error occurred
, to
_ where the _ On Error GoTo -1 _ ]
is the diversion.
Because _ On Error GoTo -1 _ effectively only “works” in the exception state, we might consider it an error handling ”thing”, or a tool we can use in error handling, as part of an error handler. Therefore it would be considered a different sort of thing to the On Error Resume Next or Resume LabelOrLineNumber
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