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.

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Note kind
CAPABILITY
Policy level
SUBJECT-TO-CHANGE
SysMLv1.x keywords
Real
Integer
String
Boolean
QuantityKind
adt$isContract
Mathematica keywords
Quantity
Integer
Real
String
True
False
MatchQ
Webel Mathematica keywords
ADT`
Webel ADT
ADT-Method
EX$Val
ADT-Constructor
EX$Val⊙isR
EX$Val⊙isQ
EX$Val⊙isB
EX$Val⊙isI
EX$Val⊙isS
adt$isContractOf
checkFatalArgs
failedArgsHeads
Keywords
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If specific sub-types such as EX$Val$R (for Real), EX$Val$I (for Integer) etc. were to be used it would mean that some Webel ADT client classes would have to use adt$isContractOf checks or similar; it's easier to just have clients carry EX$Val items uniformly and use ADT "constructor" type checks (which can leverage the Wolfram Language MatchQ and the Devel` package functions checkFatalArgs and failedArgsHeads).
Visit also: Mathematica: Webel ADT pseudo classes: An EX$Val has concise methods for testing the type of its wrapped '$$' value: isR, isI, isB, isQ, isS. These may be used in ADT "constructor" type tests.
For an explanation of the EX Layer structured data component used visit this slide:
The demo UD$EX$Component for extracted structured EX Layer data
And its associated trail sections:
SECTION: Webel ADT case study: Extracting structured data from unstructured Open XML spreadsheet data
SECTION: The Webel Abstract Data Type (ADT) stateless pseudo-classes with inheritance (with SysMLv1 models)
Relates to
Mathematica: POLICY NOTES for the Webel Abstract Data Type (ADT) pseudo classes with inheritance for the Wolfram Language
The demo UD$EX$Component for extracted structured EX Layer data
Related notes
[CONVENTION, NAMING]{STRICT} Mathematica: Webel ADT pseudo classes: NAMING CONVENTION: An UpValue that can be invoked on an ADT accepting its unique 'signature' pattern as (at least) 1st argument is called an 'ADT-Method'. They are NOT methods in the general object-oriented sense!
[POLICY]{STRICT} Mathematica: Webel ADT pseudo classes: POLICY: The expression '$$' is reserved as the primary named parameter for the defining pattern of all ADT classes that extend the universal base 'ADT' class.
Related notes (backlinks)
Related snippets (extracts)
Visit also
Mathematica: POLICY NOTES for the Webel Abstract Data Type (ADT) pseudo classes with inheritance for the Wolfram Language
Visit also (backlinks)