Mathematica: Webel ADT pseudo classes: CONVENTION: PROVISIONAL: The infix operator for calling ADT-Methods on ADT "objects" is the CircleDot (⊙ in Notebooks). ISSUE: \[CircleDot] is NOT GOOD FOR USE IN IDEs!

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Note kind
CONVENTION
NAMING
POLICY
Policy level
PROPOSED
Mathematica keywords
CircleDot
Webel Mathematica keywords
ADT`
ADT⊙get
Webel ADT
⊙
Keywords
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The use of CircleDot ⊙ as the infix operator for invoking ADT-Methods on Webel ADT "objects" is provisional: 
SetAttributes[CircleDot, {Flat, OneIdentity}];

CircleDot[adt_, fAdt_Symbol] := fAdt[adt];
Example: 
map1 = ADT$Map[<|"a" -> 1, "b" -> 2|>];

map1⊙keyList

{a, b}

It works okay in Notebooks using the slightly inconvenient sequence:

ESC  c . ESC

The ⊙ looks good, and is easy to distinguish from any non-ADT coding. It makes it clear one is working within a particular custom system. But:

Typing \[CircleDot] in IDEs over and over is rather impractical!
In IDEs it's easier to use the regular calling form with the adt "object" as 1st argument: 
keyList[map1]

{a, b}
The coding style can then get out of sync between the Notebook and the IDE

In a way this is not too bad, as it means you can tell what was coded in the IDE, as opposed to developed temporarily in a Notebook then transferred to the IDE.

Part of the reason that CircleDot was chosen is that it distinguishes the use for Webel ADTs from the user-contributed MTools OO, which uses a regular '.' period. The regular '.' period, while easy to type - and it works well in IDEs - is a dangerous can of worms (and there are some subtle side-effects of its use by MTools).

Dr Darren says:

In case you are wondering why IDE-friendliness matters, developing Wolfram Code libraries on a big complex project in the Wolfram Plug for IntelliJ IDEA is massively better (at least for the very complex projects of Webel IT Australia) than trying in the built-in .wl or .m file editor.
The Notebooks have some advantages in terms of expression awareness, and I use them in parallel to test my IDE developed code as I go. They complement each other. I sometimes develop quick test versions of new functions using a prefix 'tmp$' in the Notebook, then transfer it to the IDE once it is basically running, then polish it off in the IDE.
Relates to
Mathematica: POLICY NOTES for the Webel Abstract Data Type (ADT) pseudo classes with inheritance for the Wolfram Language
Clients of List ADTs don’t usually directly access the wrapped Lists (but can for testing with ADT⊙get which BREAKS ENCAPSULATION)
Related notes
[ANTI-PATTERN, GOTCHA, ISSUE, LIMITATION, WARNING]{INFORMATIVE} Mathematica: MTools: Argument Pattern strong type matching does not intrinsically respect inheritance (makes implementing design-by-contract and some Design Patterns less convenient). But you can use PatternTests with Webel MAll extensions.
[TIP]{INFORMATIVE} Mathematica: TIPS for living with the user-contributed MTools for Object-Orientation (until a vendor-supported OO solution is eventually provided)
[CONVENTION, POLICY, TIP]{STRICT} Mathematica: Webel ADT pseudo classes: A tricky POLICY & CONVENTION: Client packages MUST access the special "wrapped" primary '$$' via $ContextAliases! The recommended alias is "A`" (which stands of course for ADT).
[POLICY]{STRICT} Mathematica: Webel ADT pseudo classes: ADTs that define membership of ADT-classes in a domain package have ADT-signature MemberInterface[$$:None] and MUST NOT populate ADT-method UpValues in their definers.
[CONVENTION, NAMING, POLICY]{STRONG} Mathematica: Webel ADT pseudo classes: DEFINITION/CONVENTION: Functions that populate ADTs with reusable ADT-method UpValues are called 'definers' and include '$def' in the name after a Package scope indicator: Example: adt$def$ADT, my$def$MY$CleverList
[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: Definer functions MUST return the self-declared or injected 'pattern' that determines the unique "ADT-signature" of the defined ADT class.
[CONVENTION, POLICY]{STRICT} Mathematica: Webel ADT pseudo classes: POLICY: Every named concrete Abstract Data Type (ADT) has a ONE unique "signature" (which is the pattern passed to the "definer" functions). To vary a signature, define another unique ADT name.
[POLICY]{STRICT} Mathematica: Webel ADT pseudo classes: POLICY: Multiple inheritance is supported via ONE (only) ADT-Class and one or more ADT-MemberInterfaces (which have no ADT-Method UpValues)
[CONVENTION, POLICY]{STRICT} 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[]).
[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.
[POLICY]{STRICT} 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.
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CircleDot
How to construct infix operator with usual behavior?