Solved

For Crin--handling class messages

Posted on 2002-05-30
7
156 Views
Last Modified: 2010-05-02
I'm currently trying to work out a strategy for dealing with user-defined error messages occurring inside a user control, and I'm looking for advice.

Crin, since BirdsOfFire1 gave me what probably should be your points, I will offer this to you, although other experts with wwrthy ideas will also get points.

The idea is this:
I have a user control with a combobox and a command button entitled add.

The combobox lists item-IDs in a database, and when the user clicks Add, a new form appears that lets the user add a new record.

Since the database is not random-access, the user must define the ID.

If the ID is a duplicate, I intercept it during the add process and indicate that I will be appending a digit to make it unique.

---
Recently, I was told that I should offer the user the option to replace the existing record, ignore the add, or insert a new record.

Since the ID verification process is occurring inside the function that checks the ID and returns a new-unqiue-ID, what's the best way to pass back a message to the calling routine(s) so that these routines can figure out how to handle this situation?
0
Comment
Question by:rspahitz
  • 3
  • 3
7 Comments
 
LVL 1

Expert Comment

by:soferstam
ID: 7045271
public event NewID(sID as string)
...
raise event NewID ("Your ID")
0
 
LVL 22

Author Comment

by:rspahitz
ID: 7045363
That's good soferstam, but I want the event to be captured from within the control.  This may not be the best choice in the long run, but since there is a need to handle the event both within and outside the control, and all the current code is within, I'd like to simply find a new place within the control to put the message besides the sub-sub-sub-function.  I guess that technically I need to subclass some of this, but I don't want to begin that at this stage in the development cycle.
0
 
LVL 2

Expert Comment

by:Crin
ID: 7046982
Hi,

If I understood right you need return more than two parameters from the function - one for new ID and second - for the message.

soferstam is quite correct about RaiseEvent, it will fire appropriate routine in all "subscribed"  modules and classes which has defined this class variable using WithEvents keyword.

However, if you only have to get second value I'd perform it in other way - by passing some variable using ByRef.

Function VerifyID(ID as long, ByRef Message as long) as long

If ID is incorrect then
  VerifyID = newID
  Message = 1
else
  VerifyID = ID
  Message = 2
end if

end function


Sub Caller()
Dim Ret as long, ID as long, tmpID as long

ID = GetIDfromTheForm

SomeActions(SomeParameters)

tmpID = VerifyID(ID, Ret)

Select case Ret
  Case 1 'incorrect ID
     AppropriateActions1

  Case 1 'incorrect ID
     AppropriateActions2

End Select

End sub


Actually, I didn't quite understand the issue, so would you please explain with more details the GOAL you want to achieve?

Sincerely,
Crin
0
Industry Leaders: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

 
LVL 22

Author Comment

by:rspahitz
ID: 7047192
GOAL:
Have a subprocedure return a value from a calculation.  If an error occurs during the calculation, also return that.

I guess what I'm looking for is soemthing like the error object...how does VB handle that?  And how would you handle it from within a user-control?

Note: I was considering using a ByRef to return a value, but it goes against the very nature of a function which, by definition, returns a single value, and I'm trying to do things "right."
0
 
LVL 2

Accepted Solution

by:
Crin earned 100 total points
ID: 7048965
Hi,

Ok, if the function expected should NOT be placed within any class the you can use user defined type variable.
In class module you can add additional class property to appropriate value and then read it.

To do user defined type crete new project and add module, further code is obvious:

This goes for module:
----------------------------------------------------
Public Type ReturnValue
  ID As Long
  Message As Long
End Type


Public Function Check(ID As Long) As ReturnValue

If ID = 0 Then
  Check.ID = 1
  Check.Message = 0
Else
  Check.ID = ID
  Check.Message = 1
End If

End Function


And this - for some form with Command1 button on it:
----------------------------------------------------
Private Sub Command1_Click()
Dim a As New Class1, FuncResult As ReturnValue

FuncResult = a.Check(1)

If FuncResult.Message = 0 Then
  MsgBox "Error occured"
Else
  MsgBox "No error found" & FuncResult.ID
End If

End Sub

This is really more adequate way to handle numerous results passing from one function.
Ask for more details if needed.

Sincerely,
Crin



0
 
LVL 22

Author Comment

by:rspahitz
ID: 7051350
That UDT worked quite well in VB6.

I guess .net will probably change everything, but I'll worry about that in 6 months!

Thanks.
0
 
LVL 2

Expert Comment

by:Crin
ID: 7052136
I bet UDT will not change, except one good ability - to use them within classes, for VB6 it is restricted...

Sincerely,
Crin
0

Featured Post

Industry Leaders: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
Using "ScreenUpdating" 6 83
Excel - Save a copy of work book 13 91
Access 2013 combo box not working 3 56
VB6 ListBox Question 4 55
Introduction While answering a recent question about filtering a custom class collection, I realized that this could be accomplished with very little code by using the ScriptControl (SC) library.  This article will introduce you to the SC library a…
You can of course define an array to hold data that is of a particular type like an array of Strings to hold customer names or an array of Doubles to hold customer sales, but what do you do if you want to coordinate that data? This article describes…
Get people started with the utilization of class modules. Class modules can be a powerful tool in Microsoft Access. They allow you to create self-contained objects that encapsulate functionality. They can easily hide the complexity of a process from…
This lesson covers basic error handling code in Microsoft Excel using VBA. This is the first lesson in a 3-part series that uses code to loop through an Excel spreadsheet in VBA and then fix errors, taking advantage of error handling code. This l…

680 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question