Kotlin Veil

A Kotlin demonstration of Yegor's "veiled objects"

Try it

$ ./run.sh

Build locally

$ ./mvnw clean verify

Build with CI (Docker)

$ ./batect build

Notes

As this code is a demonstration, it comes with caveats:

The code does not use an actual database, rather a "fake" data source
Implementation uses JDK proxies
Data rows representing objects each has a unique "id" key

Features

Demonstrates "piercing the veil" and "unpierceable veils"
JDK reflection on veiledness by casting to a Veiled<T>, and using the pierced property, or the veiled(prop-ref) function

One might say, "Use an ORM"! The point of veiled objects is lighter-weight code without the complexity of an ORM. Contrawise,

Demonstration

Output of main demonstrating veiled, unveiled, and pierced:

NOTE: Bob has props: a, b, veiled.
NOTE: Prop veiled is to show that the data value is not masked by Veilable.

PIERCED
-------

== Read veiled, then pierced if pierceable (true), then underlying real object
VEILING -> getA=2
PIERCING VEIL
CALLING public abstract java.lang.String hm.binkley.veil.Bob.getB()
FETCHING[1] -> SELECT b FROM Bob WHERE ID = :id
CALLING public abstract int hm.binkley.veil.Bob.getVeiled()
VEILED: Bob{a=2, b=apple, veiled=17}

CALLING public abstract int hm.binkley.veil.Bob.getA()
FETCHING[1] -> SELECT a FROM Bob WHERE ID = :id
CALLING public abstract java.lang.String hm.binkley.veil.Bob.getB()
FETCHING[1] -> SELECT b FROM Bob WHERE ID = :id
CALLING public abstract int hm.binkley.veil.Bob.getVeiled()
MAYBE-PIERCED: Bob{a=222, b=apple, veiled=17}

CALLING public java.lang.String java.lang.Object.toString()
FETCHING[1] -> SELECT a FROM Bob WHERE ID = :id
FETCHING[1] -> SELECT b FROM Bob WHERE ID = :id
REAL: RealBob(1){a=222, b=apple, veiled=17}

PIERCED? true
VEILED-A? false
VEILED-B? false
IS REFLECTIVE VEILED MASKED? false

UNPIERCED
---------

== Read veiled, then pierced if pierceable (false), then underlying real object
VEILING -> getA=2
CALLING public abstract java.lang.String hm.binkley.veil.Bob.getB()
FETCHING[1] -> SELECT b FROM Bob WHERE ID = :id
CALLING public abstract int hm.binkley.veil.Bob.getVeiled()
VEILED: Bob{a=2, b=apple, veiled=17}

VEILING -> getA=2
CALLING public abstract java.lang.String hm.binkley.veil.Bob.getB()
FETCHING[1] -> SELECT b FROM Bob WHERE ID = :id
CALLING public abstract int hm.binkley.veil.Bob.getVeiled()
MAYBE-PIERCED: Bob{a=2, b=apple, veiled=17}

CALLING public java.lang.String java.lang.Object.toString()
FETCHING[1] -> SELECT a FROM Bob WHERE ID = :id
FETCHING[1] -> SELECT b FROM Bob WHERE ID = :id
REAL: RealBob(1){a=222, b=apple, veiled=17}

PIERCED? false
VEILED-A? true
VEILED-B? false
IS REFLECTIVE VEILED MASKED? false

binkley / kotlin-veil