Topic: fix Nested If-Then-Statement

[jtm2020hyo]

hello everyone.

 

Probably I found a bug with the VBScript. I was creating and experimenting a lot with the VBScript function if-then-elseif-else statement and I found something that before saving my drawing was working, but know that I was checking again simply stop working.

 

 



 



I was linking multiple functions to the function name "NAME_BY_OBJECT" which generates a different name per each different object. In images 1 and 2, everything is correct...

 

... but something weird happens with I add the object type "Hanger":

 





 

... again everything works correct, but just with hangers, but I was checking the cable trays and cable trays fitting this happens:

 




 

 

I do not what happens here.

 Then:

1) am I doing something bad?

2)if yes, how can I fix this?

3) if not, What Is wrong, and what alternatives exist?

 

PD: attached files


before:

Code: [Select]


If "[ObjectType]" = "Cable Tray" Then
RESULT = "[NAME_CABLE_TRAY]"

ElseIf "[ObjectType]" = "Cable Tray Fitting" Then
RESULT = "[NAME_CABLE_TRAY_FITTING]"

Else
RESULT = "NA"

End If
 
after:

 

Code: [Select]


If "[ObjectType]" = "Cable Tray" Then
RESULT = "[NAME_CABLE_TRAY]"

ElseIf "[ObjectType]" = "Cable Tray Fitting" Then
RESULT = "[NAME_CABLE_TRAY_FITTING]"

ElseIf "[ObjectType]" = "Hanger" Then
RESULT = "[NAME_HANGER]"

Else
RESULT = "NA"

End If


 

[JohnK]

I don't do a lot of VB script stuff so you will have to tell me if this is legal or not.

Nested IF-Then statements are bad programming. You should always avoid using them as much as possible. And you should never use an ELSE statement after a return statement. Although, I don't think the "RESULT" is necessarily a "return" statement in VB script so this is why I said you need to tell me if the code snip I post is legal or not.

You are better off with small IF statements like below. You establish a default value for your variable (if you absolutely need one) and you use small IF statements like this. The theory is that when, and if, the RESULT keyword were a return (in which case you'd omit the first line) the code would stop executing when an if statement became true.


IF the RESULT keyword is not a "return" statement then you should be using something like:

Code: [Select]

RESULT = "NA"
If "[ObjectType]" = "Cable Tray" Then
RESULT = "[NAME_CABLE_TRAY]"
End If

If "[ObjectType]" = "Cable Tray Fitting" Then
RESULT = "[NAME_CABLE_TRAY_FITTING]"
End If

If "[ObjectType]" = "Hanger" Then
RESULT = "[NAME_HANGER]"
End If
However, if the RESULT keyword is a "return" statement then the code would look like this:

Code: [Select]

If "[ObjectType]" = "Cable Tray" Then
RESULT = "[NAME_CABLE_TRAY]"
End If

If "[ObjectType]" = "Cable Tray Fitting" Then
RESULT = "[NAME_CABLE_TRAY_FITTING]"
End If

If "[ObjectType]" = "Hanger" Then
RESULT = "[NAME_HANGER]"
End If

Otherwise, my guess would be there is a limit as to the elseif statements, meaning you are only allowed one.

[jtm2020hyo]

I don't do a lot of VB script stuff so you will have to tell me if this is legal or not.

Nested IF-Then statements are bad programming. You should always avoid using them as much as possible. And you should never use an ELSE statement after a return statement. Although, I don't think the "RESULT" is necessarily a "return" statement in VB script so this is why I said you need to tell me if the code snip I post is legal or not.

You are better off with small IF statements like below. You establish a default value for your variable (if you absolutely need one) and you use small IF statements like this. The theory is that when, and if, the RESULT keyword were a return (in which case you'd omit the first line) the code would stop executing when an if statement became true.


IF the RESULT keyword is not a "return" statement then you should be using something like:

Code: [Select]

RESULT = "NA"
If "[ObjectType]" = "Cable Tray" Then
RESULT = "[NAME_CABLE_TRAY]"
End If

If "[ObjectType]" = "Cable Tray Fitting" Then
RESULT = "[NAME_CABLE_TRAY_FITTING]"
End If

If "[ObjectType]" = "Hanger" Then
RESULT = "[NAME_HANGER]"
End If
However, if the RESULT keyword is a "return" statement then the code would look like this:

Code: [Select]

If "[ObjectType]" = "Cable Tray" Then
RESULT = "[NAME_CABLE_TRAY]"
End If

If "[ObjectType]" = "Cable Tray Fitting" Then
RESULT = "[NAME_CABLE_TRAY_FITTING]"
End If

If "[ObjectType]" = "Hanger" Then
RESULT = "[NAME_HANGER]"
End If

Otherwise, my guess would be there is a limit as to the elseif statements, meaning you are only allowed one.

sorry for the late answer. I am testing a lot of things to solve this problem, I was testing your code, your code works, but just when is not a nested function, this still does not solve the nested if-statement because probably exist any undocumented limit in the number of characters that support each function or similar limit and I am trying to found it. So I will keep updating this post in the future.

PD: Thanks for your help and thanks for being a great moderator.

[jtm2020hyo]

I don't do a lot of VB script stuff so you will have to tell me if this is legal or not.

Nested IF-Then statements are bad programming. You should always avoid using them as much as possible. And you should never use an ELSE statement after a return statement. Although, I don't think the "RESULT" is necessarily a "return" statement in VB script so this is why I said you need to tell me if the code snip I post is legal or not.

You are better off with small IF statements like below. You establish a default value for your variable (if you absolutely need one) and you use small IF statements like this. The theory is that when, and if, the RESULT keyword were a return (in which case you'd omit the first line) the code would stop executing when an if statement became true.


IF the RESULT keyword is not a "return" statement then you should be using something like:

Code: [Select]

RESULT = "NA"
If "[ObjectType]" = "Cable Tray" Then
RESULT = "[NAME_CABLE_TRAY]"
End If

If "[ObjectType]" = "Cable Tray Fitting" Then
RESULT = "[NAME_CABLE_TRAY_FITTING]"
End If

If "[ObjectType]" = "Hanger" Then
RESULT = "[NAME_HANGER]"
End If
However, if the RESULT keyword is a "return" statement then the code would look like this:

Code: [Select]

If "[ObjectType]" = "Cable Tray" Then
RESULT = "[NAME_CABLE_TRAY]"
End If

If "[ObjectType]" = "Cable Tray Fitting" Then
RESULT = "[NAME_CABLE_TRAY_FITTING]"
End If

If "[ObjectType]" = "Hanger" Then
RESULT = "[NAME_HANGER]"
End If

Otherwise, my guess would be there is a limit as to the elseif statements, meaning you are only allowed one.

Hi again, I finally found a possible solution.

your code posted here:

Code: [Select]

RESULT = "NA"
If "[ObjectType]" = "Cable Tray" Then
RESULT = "[NAME_CABLE_TRAY]"
End If

If "[ObjectType]" = "Cable Tray Fitting" Then
RESULT = "[NAME_CABLE_TRAY_FITTING]"
End If

If "[ObjectType]" = "Hanger" Then
RESULT = "[NAME_HANGER]"
End If
... works and solve the problem but I need to insert this structure in each every formula function, but I need to add an additional comparison statement and filter objects for finally reduce the number of caracters.

... something like this:

Code: [Select]

RESULT = "NA"
If ("[ObjectType]") = ("Cable Tray") And ("ParType" = "Trunking") Then
RESULT = "[NAME_CABLE_TRAY]"
End If

If ("[ObjectType]") = ("Cable Tray Fitting") And ("ParType" = "Elbow")Then
RESULT = "[NAME_CABLE_TRAY_FITTING]"
End If

If ("[ObjectType]") = ("Hanger") Then ("Anchor_System" = "Electric")
RESULT = "[NAME_HANGER]"
End If
but this need to analyze each formula and loss completely their beauty, for that motive I was adding the If ElseIf Else End If Statement in the ending"

Code: [Select]

If "[ObjectType]" = "Cable Tray" Then
RESULT = "[NAME_CABLE_TRAY]"

ElseIf "[ObjectType]" = "Cable Tray Fitting" Then
RESULT = "[NAME_CABLE_TRAY_FITTING]"

ElseIf "[ObjectType]" = "Hanger" Then
RESULT = "[NAME_HANGER]"
Else
        RESULT = "NA"
End If

This was the original script and should work, in theory, but it doesn't. The Else statement, in the end, shouldn't make the code work? I mean, Else in the end should equivalent to the "RESULT=" at the start. I am doing something bad?

[JohnK]

Glad my code works.

I wouldn't worry too much about an undocumented limit in the IF-IFELSE-ELSE statement; I would just avoid using them. They are typically a very bad programming method.

Try to replace this:

Code: [Select]

If(boolean_expression) Then
   Statement n
ElseIf (boolean_expression) Then
   Statement n
ElseIf (boolean_expression) Then
   Statement n
Else
   Statement n
End If
With this methodology:

Code: [Select]

Select Case expression
   Case expressionlistN
      statementN
   Case expressionlistN
      statementN
  Case Else
      elsestatementN
End Select
You are correct, the ELSE statement is meant to offer a "default" value.

The code block I posted may not be as `pretty' but it reads so much cleaner (there is little doubt as to what your intentions are). That is to say (from the standpoint of the processor):
"VARIABLE SET. TEST: TEST-FAILED. ... TEST: VARIABLE REDEFINED"

[Greg B]

1.  Been a long time since I did any VB.
2.  Elseif is NOT bad in VB.  Cleans up the code and does the same thing as breaking it all down.
3.  My gut says it is the word HANGER that is causing the issue.  See #1.

Have you tried testing different labels instead of HANGER?

[jtm2020hyo]

1.  Been a long time since I did any VB.
2.  Elseif is NOT bad in VB.  Cleans up the code and does the same thing as breaking it all down.
3.  My gut says it is the word HANGER that is causing the issue.  See #1.

Have you tried testing different labels instead of HANGER?

I agree, adding a single name not should broken formula... well the problem already was solved.