Mathematica: Webel ADT pseudo classes: 'Q: Do I have to use these EX$Val scalar "atom" thingies and the EX$Row, EX$RowList, and EX$RowMap? Can't I just use Wolfram Language Lists and Associations?' A: Of course you can also use the basic Wolfram Language!
Mathematica: Webel ADT pseudo classes: An EX$Val has concise methods for testing the type of its wrapped '$$' value: isR, isI, isB, isQ, isS. These may be used in ADT "constructor" type tests.
Mathematica: Webel ADT pseudo classes: The validity of the type of a wrapped '$$' value of an EX$Val may be checked in ADT "constructors" which have type checking utility support. This strategy has been chosen over sub-types of EX$Val.
Mathematica: Webel ADT pseudo classes: There does not seem to be a way to register ::usage specific to a Webel ADT-Method (TagSetDelayed UpValue). The Webel libraries offer method documentation support via the HelpO` class/method registry.
Mathematica: Webel ADT pseudo classes: Webel ADT-Methods support Wolfram Language Options[] as TagSetDelayed UpValues (but there are some pros and cons). Webel ADT-Methods work with the Webel HelpO` class/method registry, including rich help on options.
Mathematica: Webel OpenXML: The XL$Cell value accessor XL$Cell⊙valReal has no units-awareness; prefer the US$Cell value accessor US$Cell⊙val, which can return a Quantity.
Mathematica: Webel ADT pseudo classes: POLICY: Where an ADT-Method uses UUID-driven Once[] caching the trigger argument is a String '$uuid' which MUST have a default None and MUST be the first argument that has a default.
Mathematica: Webel ADT pseudo classes: The SysMLv1 models are supported by custom stereotypes with icons. Some of these indicate OO-similar use of ADT-Methods and departures from formal Abstract Data Type (ADT) definitions.
Mathematica: Webel ADT pseudo classes: POLICY: The ADT-Methods of an ADT-Class are created as TagSetDelayed UpValues using the 'signature' of the ADT-Class and its defining 'pattern' as 1st argument
Mathematica: Webel ADT pseudo classes: NAMING CONVENTION: An UpValue that can be invoked on an ADT accepting its unique 'signature' pattern as (at least) 1st argument is called an 'ADT-Method'. They are NOT methods in the general object-oriented sense!
Mathematica: Webel ADT pseudo classes: There is an 'ADT' universal base that has no supers. It "blesses" every other sub-class ADT by populating it with some common ADT-Method UpValues against a signature pattern via the 'adt$def$All[]' definer function.
Mathematica: Webel ADT pseudo classes: POLICY: The Abstract Data Types (ADTs) are stateless functional (although inheritance and overrides are supported), with no caching by default (although there is nice optional caching using CreateUUID[] and Once[]).
