RFR: JDK-8289106: Add model of class file versions to core reflection [v5]

[Roger Riggs]

On Mon, 1 Aug 2022 23:05:58 GMT, Joe Darcy <darcy at openjdk.org> wrote:

>> Probably by creating and using shared instances of `java.util.Function` which would also allow deduplicating the code.
>
>> Is there another way to implement this that does not create 19 anonymous classes with a single overloaded method?
> 
> Overriding a method in an enum constant specific class is one way to implement constant-specific behavior. Textually, I thought it had the advantage of having the class file version specific behavior close to the latest version behavior.
> 
> This could be refactored in various ways, such as having AccessFlag.locations(ClassFileFormatVersion cffv) start with a switch over the location which implemented the enum constant specific behavior. Or the set of parameters of the enum constructor could be augmented to cover more cases (empty until $VERSION, then $LOCATIONS, etc.), with constant-specific overrides just constants with unique patterns like STRICT.

True, many ways to factor the code.  Another possibility is add a field to the enum that holds a `java.util.Function<Iteger, Set<Location>>)` and initialize it each with a lambda of the code now in the locations(cffv) method that maps the cffv to the set of locations.

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PR: https://git.openjdk.org/jdk/pull/9299