Set
A Set is useful for lists of topics, categories, and tags. Sets are a special type of string, within which discrete values are delimited by semicolons:
"astronomy;marine biology;chemistry"
"dogs;cats"
"cats"
"3;9;15"
"dog;9.66;15"
"dogs;a big cat;lions"
Note that the Set is always a string even if the values happen to be numbers. A Set can have a single value, e.g. the third example above. With a single value there is no need to add a final semicolon and the same is true for the last of multiple values. Tinderbox will not mind if you supply a semicolon there (or after the last of multiple values), it will just strip it off as it processes the data. The default Set value is an empty string. A Set-type differs from a List-type in that duplicate values are not allowed.
To apply values directly to a Set-type attribute via the Displayed Attributes or via Info view or via the Inspector's Quickstamp, simply type the values as seen into the data box. In all these methods, you do not need to add enclosing quotes, but each discrete value should be separated with a semi-colon.
If setting a Set via action code note the string must be quoted:
$KeyAttributes="Width;Height;OnAdd"
With a Set you can add/remove individual or multiple values and test its contents.
From v9, Set attributes have been reimplemented to improve performance with large sets, but a Set is now more aggressive in asserting their control of the sequence of their elements. Compared to previous use, the stored order of items in the Set's value list are much more likely to change from the order as originally entered.
Adding and deleting values
In actions, + adds an item to a set if it is not already present, and - removes it if it is present. Values must be enclosed in double quotes. If $PetTypes' value is "cats;dogs"
$PetTypes=$PetTypes+"dogs" leaves $PetTypes unchanged, since 'dogs' is already in $PetTypes
$PetTypes=$PetTypes-"dogs" leaves only "cats" as a value.
Testing (querying) sets & Lists
To test a Set or List, use the .contains() operator, syntax AttributeName.contains("tested_value"), returns true if any set/list discrete value exactly matches the designated tested_value; if case sensitivity is irrelevant for the query use .icontains(). If a user attribute $PetTypes has a value of "dogs;cats" then
$PetTypes.contains("dogs") is true,
but
$PetTypes.contains("dog") is false
This is because Set/List matching does not allow partial matches, as via regex, unlike with String-type data.
Other variants:
$PetTypes.contains("Dogs").lowercase is true
$PetTypes.icontains("DOGS") is true
It can be useful to use a stored value as the search term, for instance using the name of an agent as the search term:
$PetTypes.contains($MyString) is true
Listing and Exporting sets
The format() action operator, and newer .format() dot operator offer ways to turn sets into HTML lists for export. See Exporting Set-type data for more.
Set data vs. List data
List-type attributes came to Tinderbox after Sets. Lists, unlike Sets, allow duplicate values and Sets can better be thought of as de-duped versions of Lists, i.e. lists with no duplicate entries.
To de-dupe a List, simply put its contents into a Set-type attribute:
$MySet=$MyList;
Escaping literal semi-colons
If a list item must contain a semi-colon, it must be escaped, using a backslash, '\;'. Once the backslash is entered, it disappears and the list item containing the semi-colon is enclosed in double-quotes. Do not try to escape a value by adding the quotes directly, use the backslash method. Action code methods to make lists will treat a '\;' in an input string as an escape and act accordingly. Consider using String.replace() as a method for escaping backslashes (though only where intended!).
Sorting order
As for String Data Type, using the literal string value of the Set (e.g. a 3-item Set would be "ant;bee;cow").
Set-type Attributes