ListToggle ( InList ; InValue )

Adds or removes given Value from given List

Average rating: 4.9 (26 votes) Log in to vote

Richard DeShong - Show more from this author
Logic Tools
http://logictools.com

Sample input:

ListToggle ( "A¶B¶C¶B", "B" )

Sample output:

"A¶C"

Function definition: (Copy & paste into FileMaker's Edit Custom Function window)

Case(
   IsEmpty( InValue ) or InValue = "Empty" ; InList ;
   IsEmpty( InList ) or InList = "Empty" ; InValue ;
   IsEmpty( FilterValues( InList ; InValue ) ) ; InList & "¶" & InValue ;
   Let( ListMinus = Substitute( "¶" & InList ; "¶" & InValue ; "" ) ;
     Middle( ListMinus ; 2 ; 999999999 )
   )
)
/*
   Purpose: If InValue is NOT in InList, then ADD it; Else REMOVE it.

   NOTES:
   1) It removes all repetitions of InValue.
   2) This version presumes the list is less than a billion characters.
   3) This function is used in conjunction with custom function SetVar(),
      which sets a variable to "Empty" if it is empty.
      If you do not use SetVar(), then remove the two initial "or" statements:
         or InValue = "Empty"
         or InList = "Empty"
*/

Add or Remove a given value from the list.
A new value is added to the end of the list.
Substitute() is used to remove, so all repetitions of the value are removed.
Note that this does not "clean up" the list (it does not remove blank lines).
I typically use this for UI selection and conditional formatting.

Adapted from ideas by David Head and Bruce Robertson and their AddRemoveListItem(s) functions. The main change was to put the Let() statement inside the Case() statement. I think this makes the function more efficient when it is likely that the list is empty.

~~~ Design Notes ~~~

This is part of a series of LIST functions.
ListAdd(), ListAddUnique(), ListExist(), ListGet(), ListToggle().
Each uses the same name format: List
Each uses the same parameter format: InList; InValue.

They also work in concert with two SET functions:
SetVar() and SetField()
These are all designed to work with variables and to
keep the variables from being un-set (removed from memory),
by using the string "Empty" to indicate IsEmpty().
Example:
If a field, MyField, is empty and I use SetVar(),
MyVariable = SetVar( MyField )
Then MyVariable is now = "Empty"
~~~

Comments

		Don Wieland, DW Data Concepts Feb 10, 2024
Hi Richard - I ran across your function in hope to use it. It did not quite do exactly what I needed, so I ended up compiling my own. If interested, I'd appreciate your feedback on it. toggle_value_in_value_list(vList, theValue) Thanks for submitting your function to inspire me! Don

		Richard DeShong, Logic Tools Feb 12, 2024
Don, your function seems to do the exact same thing as this function. But it has an unneeded Let(), and uses a slower While-Replace, instead of the faster Substitute that this function uses.

Note: these functions are not guaranteed or supported by BrianDunning.com. Please contact the individual developer with any questions or problems.

ListToggle ( InList ; InValue )

Comments

Support this website.

Support this website.