Groovy Roadmap

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Groovy 4 Update
Presented by
Dr Paul King
Object Computing &
VP Apache Groovy
© 2022 Object Computing, Inc. (OCI). All rights reserved.
See also: https://github.com/paulk-asert/upcoming-groovy/tree/master/Four

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Groovy
• Multi-faceted programming language
• Static and dynamic natures
• Strengths:
• Extensibility including runtime and
compile-time metaprogramming
• Java-like syntax and integration
• Domain Specific Language support
• Scripting

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Groovy status in 2022: Healthy
• > 600K lines
of source code
• > 19K commits
• > 8K issues &
enhancements
resolved
• > 500 contributors
• > 200 releases
• > 1B downloads
and accelerating

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Parrot Parser
• Lambdas
• Method references
• New operators & Safe index
===, !===, ?=, !in, !instanceof
• Additional Java compatibility
GDK enhancements
• average(), takeBetween(), shuffle(), …
AST transforms
• @NullCheck
• @Groovydoc
Libraries/Tooling
• Split package
remediation
• Java module system
improvements
• JSR-308 Annotation
improvements
• YAML builder/slurper
Groovy 3 - Summary

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Consolidation & Structuring
• Maven coordinates
• Module changes
• Indy only, Parrot only
• ~33% smaller zip
• ~10% smaller core jar
Language Features
• Switch expressions
• Records & Sealed types
• Language integrated query
• Improved type annotations
Libraries/Tooling
• Built-in type checkers
• Built-in macro methods
• TOML builder/slurper
• JavaShell
• Improved ranges
AST transforms
• @POJO
• @RecordType
• Groovy Contracts
GDK enhancements
Groovy 4 - Summary

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Important naming/structuring changes
Maven coordinate change
org.codehaus.groovy org.apache.groovy

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Important naming/structuring changes
Maven coordinate change
org.codehaus.groovy org.apache.groovy
Note: Doesn’t imply all internal package names have been changed.
That is a parallel and on-going activity which we do as opportunities arise.
We don’t break backwards compatibility when we don’t have to.

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Module changes
Removed modules
groovy-bsf groovy-jaxb
New optional modules
groovy-contracts
groovy-ginq
groovy-macro-library
groovy-toml
groovy-typecheckers
Module changes for groovy-all
groovy-testng: included in all optional
groovy-yaml: optional included in all

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Module changes
Split packaging legacy package removal
groovy-xml:
Also: groovy-ant, groovy-swing, groovy-test, …
More details:
https://groovy-lang.org/releasenotes/groovy-3.0.html#Groovy3.0releasenotes-Splitpackages
2.5 3.0 4.0
groovy.util.XmlParser
groovy.util.XmlSlurper
groovy.util.XmlParser
groovy.util.XmlSlurper
groovy.xml.XmlParser
groovy.xml.XmlSlurper
groovy.xml.XmlParser
groovy.xml.XmlSlurper

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Legacy consolidation
Old parser removal
Antlr 2 Antlr4
Classic bytecode generation removal
Classic Indy

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• Module changes
Language Features
Libraries/Tooling
• JavaShell
• Improved ranges
AST transforms
• @POJO
• @RecordType
GDK enhancements
Groovy 4 - Summary

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Switch expressions
def a = 9
def result = switch(a) {
case 6, 8 -> 'b'
case 9 -> 'c'
default -> 'z'
}
assert 'c' == result

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Switch expression enhancements
enum Day { Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday }
import static Day.*
def isWeekend(Day d) {
switch(d) {
case Monday..Friday -> false
case [Sunday, Saturday] -> true
}
}
assert [Sunday, Monday, Friday].collect{ isWeekend(it) }
== [true, false, false]

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Switch expression: yield variation
enum Day { Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday }
import static Day.*
def isWeekend(Day d) {
return switch(d) {
case Monday..Friday: yield false
case { it.toString()[0] == 'S' }: yield true
}
}
assert [Sunday, Monday, Friday].collect{ isWeekend(it) }
== [true, false, false]

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Switch expression: differences to Java
Java Groovy
JDK versions 14+ (12/13 preview) 8+
“ -> ” syntax (switch rule)  
“ : … yield” syntax  
Supported case selector
expressions
Constant
• Boolean, Number, String
Enum constant
Constant
• Boolean, Number, String, null
Enum constant
List expression
Range expression
Closure
Regex Pattern
Class expression
Enhanced switch
(17-19 preview)
Type pattern
Guard/when
Null
Class or Closure
Closure
already supported
Extensible via isCase  

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Records
• Shorthand for data classes (immutable DTOs)
• Produces a class that:
• Is implicitly final
• Has a private final field for each property, e.g. color
• Has an accessor method for each property of the same name, e.g. color()
• Has a default Point(int, int, String) constructor
• Has a default serialVersionUID of 0L
• Has implicit toString(), equals() and hashCode() methods
record Point(int x, int y, String color) { }
def blueOrigin = new Point(0, 0, 'Blue')
Incubating

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@RecordType
Alternative style for:
@RecordType
class Cyclist {
String firstName
String lastName
}
def richie = new Cyclist('Richie', 'Porte')
Incubating
record Cyclist(String firstName, String lastName) { }

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Records: Groovy enhancements
record Material(String name, int strength, String warranty, String color) { }
def straw = new Material('Straw', 4, 'light winds only', 'yellow')
assert straw.toList() == ['Straw', 4, 'light winds only', 'yellow']
assert straw[1] == 4
assert straw.size() == 4
Incubating

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def sticks = new Material(name: 'Sticks', strength: 42, warranty: 'light winds', color: 'brown')
assert sticks.toMap() == [name: 'Sticks', strength: 42, warranty: 'light winds', color: 'brown']
assert sticks[3] == 'brown'
Incubating

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@RecordOptions(copyWith = true, components = true)
def sticks = new Material(name: 'Sticks', strength: 42, warranty: 'light winds', color: 'brown')
assert sticks.toMap() == [name: 'Sticks', strength: 42, warranty: 'light winds', color: 'brown']
assert sticks[3] == 'brown'
def bricks = sticks.copyWith(name: 'Bricks', color: 'red', warranty: 'heavy winds')
assert bricks.components() instanceof Tuple4
assert bricks.components().toList() == ['Bricks', 42, 'heavy winds', 'red']
Incubating

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Native vs emulated Records
@RecordOptions(mode=RecordTypeMode.AUTO) // default, not needed
record Person(String name, int age) {}
@RecordOptions(mode=RecordTypeMode.NATIVE)
record Point(int x, int y, String color) { }
@RecordOptions(mode=RecordTypeMode.EMULATE)
@RecordType
class Cyclist {
String firstName
String lastName
}
Regardless of keyword
or annotation style,
native or emulated records
can be selected:
• AUTO – native if JDK16+
• NATIVE – record info in
bytecode, error if JDK < 16
• EMULATE – record info
captured as annotations
(works on JDK8+ but won’t
be seen as records by Java)

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Records: differences to Java
Java
Record
Groovy
Emulated Record
Groovy
Native Record
JDK version 16+ 8+ 16+
Serialization Record spec Traditional Record spec
Recognized by Java, Groovy Groovy Java, Groovy
Standard features
• accessors
• tuple constructor
• toString, equals, hashCode
  
Optional enhancements  toMap, toList, size, getAt, components,
copyWith, named-arg constructor
Customisable via coding   
Customisable via AST
transforms (declarative)
  

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Record-like functionality: summary
Accessors toString()
equals()
hashCode()
Constructor
Groovy
version
JDK
version
Standard
Groovy
JavaBean
From
Object
From
Object
Named-arg 1.0+ 6+
@Immutable JavaBean
From
properties
From
properties
Tuple and
named-arg
1.7+ 6+
@ToString -
From
properties
- - 1.8+ 6+
@EqualsAnd
HashCode
- -
From
properties
- 1.8+ 6+
@Canonical JavaBean
From
properties
From
properties
Tuple and
named-arg
1.8+ 6+
Emulated &
native records
Record
From
components
From
components
Tuple and
named-arg
4.0+
8+ &
16+

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Sealed Type Motivation
• Inheritance is a powerful abstraction for building systems
class Shape { … }
class Square extends Shape { … }
final class Circle extends Shape { … }
Incubating

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• There are scenarios where limiting inheritance has benefits
• Less defensive programming in parent classes
• To support additional compiler checks, e.g. pattern matching/casts
• Traditional mechanisms for limiting inheritance are crude
• Using final stops all inheritance (not applicable to interfaces)
• Package-private parent classes don’t provide an accessible parent
abstraction (not applicable to interfaces)

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• There are scenarios where limiting inheritance has benefits
• Less defensive programming in parent classes
• To support additional compiler checks, e.g. pattern matching/casts
• Traditional mechanisms for limiting inheritance are crude
• Using final stops all inheritance (not applicable to interfaces)
• Package-private parent classes don’t provide an accessible parent
abstraction (not applicable to interfaces)
• Sealed type
• Provides a fixed set of children rather than all or nothing
• Decouples accessibility from extendibility
• Easier to add new methods, harder to add new types
• Unsealed type
• Easy to add new types, harder to add new methods

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abstract class ShellOp {
abstract String getOp()
def calc(int one, int two) {
// powerful approach - use with care
new GroovyShell().evaluate("$one $op $two")
}
}
class Multiply extends ShellOp { String op = "*" }
class Add extends ShellOp { String op = "+" }
def ops = [new Add(), new Multiply()]
assert ops*.calc(40, 2) == [42, 80]

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abstract class ShellOp {
def calc(int one, int two) {
// powerful approach - use with care
}
}
def ops = [new Add(), new HackedAdd(), new Multiply()]
assert ops*.calc(40, 2) == [42, 42, 80]
class HackedAdd extends ShellOp {
String op = "+ (println(new File('/etc/passwd').text) ?: 0) +"
}
• Contrived code injection
• Could be hardened
in various ways

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sealed abstract class ShellOp permits Multiply, Add {
int calc(int one, int two) {
}
}
def ops = [new Add(), new Multiply()]
assert ops*.calc(40, 2) == [42, 80]
• Sealed hierarchy
also limits potential
for such scenarios

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abstract class Material {
abstract String getColor()
String toString() { "${getClass().name} with color ${color.toLowerCase()}" }
}
class Straw extends Material { String color = "Yellow" }
class Wood extends Material { String color = "Brown" }
class Brick extends Material { String color = "Red" }
def materials = [new Straw(), new Wood(), new Brick()]
assert materials*.toString() == [
'Straw with color yellow',
'Wood with color brown',
'Brick with color red'
]
• More frequently implicit
or hidden implementation
details or assumptions

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}
]
class Glass extends Material {
String color = null // transparent
}

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}
]
class Glass extends Material {
String color = null // transparent
}
new Glass().toString() // NullPointerException
• Classes added
later may yield
unexpected
results

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sealed abstract class Material permits Straw, Wood, Brick {
}
]
• Could be hardened
in various ways or
again use sealed

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String warranty() {
switch(this) {
case Straw -> 'Use only in light winds'
case Wood -> 'Okay for light breezes'
case Brick -> 'Withstands huffing and puffing'
}
}
}
class Straw extends Material { }
class Wood extends Material { }
class Brick extends Material { }
assert materials*.warranty() == [ 'Use only in light winds',
'Okay for light breezes', 'Withstands huffing and puffing' ]
• Switch
expressions
are a special
case

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String warranty() {
switch(this) {
}
}
}
class Glass extends Material { }
new Glass().warranty() // null (or error)
• Switch
expressions
are a special
case

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sealed abstract class Material permits Straw, Wood, Brick {
String warranty() {
switch(this) {
}
}
}
class Glass extends Material { } // × compile error
• This becomes
a compile-time
error which
forces it to be
handled

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Sealed Types (more details)
@Sealed(permittedSubclasses=[Diamond,Circle]) class Shape { }
final class Diamond extends Shape { }
final class Circle extends Shape { } • Class or abstract class
• Annotation style

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final class Circle extends Shape { }
sealed trait Triangle permits Equilateral, Isosceles { }
final class Equilateral implements Triangle { }
final class Isosceles implements Triangle { }
• Trait
• Keyword style

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sealed interface Polygon { }
final class Square implements Polygon { }
final class Rectangle implements Polygon { }
• Interface
• Keyword style
• Inferred subclasses

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You can choose either keyword
or annotation style
• Annotation style might be useful
when using older tools (IDEs,
CodeNarc)
• Keyword style generally preferred

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Native vs emulated Sealed Types
@SealedOptions(mode=SealedMode.AUTO) // default, not needed
@SealedOptions(mode=SealedMode.NATIVE)
@SealedOptions(mode=SealedMode.EMULATE)
Regardless of keyword
or annotation style,
native or emulated sealed
types can be selected
• AUTO – native if JDK17+
• NATIVE – sealed info in
bytecode, error if JDK < 17
• EMULATE – sealed info
captured as annotations
(works on JDK8+ but won’t
be seen as sealed by Java)

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Sealed Types – Good for ADTs
@Sealed interface Tree {}
@Singleton final class Empty implements Tree {
String toString() { 'Empty' }
}
@Canonical final class Node implements Tree {
T value
Tree left, right
}
Tree tree = new Node<>(42,
new Node<>(0, Empty.instance, Empty.instance), Empty.instance)
assert tree.toString() == 'Node(42, Node(0, Empty, Empty), Empty)'

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Sealed Types – Hybrid hierarchies
sealed class Shape permits Circle, Polygon, Rectangle { }
non-sealed class Polygon extends Shape { }
final class Pentagon extends Polygon { }
sealed class Rectangle extends Shape permits Square { }
final class Square extends Rectangle { }

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Shape
Circle Polygon Rectangle
Pentagon Square

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• Groovy follows Scala style of non-
sealed being optional
• We envisage a future CodeNarc rule
which could enforce the Java style

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Sealed types: differences to Java
Java
Sealed Type
Groovy Emulated
Sealed Type
Groovy Native
Sealed Type
JDK version 17+ 8+ 17+
Recognized by Java, Groovy Groovy Java, Groovy
“non-sealed” to reopen Required Optional Optional

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Language Integrated Query (GQ, GINQ)
• Language level support for SQL-like query expressions
across aggregations
• Currently traditional collections including e.g. parsed JSON
• Later SQL databases too
Incubating

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• Projection
• Filtering
• Joins
• Aggregations
• Sorting
• Grouping
• Pagination
• Nesting
• Windows
GINQ from p in persons
leftjoin c in cities on p.city.name == c.name
where c.name == 'Shanghai'
select p.name, c.name as cityName
from p in persons
groupby p.gender
having p.gender == 'Male'
select p.gender, max(p.age)
from p in persons
orderby p.age in desc, p.name
select p.name
from n in numbers
where n > 0 && n <= 3
select n * 2
from n1 in nums1
innerjoin n2 in nums2 on n1 == n2
select n1 + 1, n2

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Language Integrated Query Motivation
def people = [new Person('Daniel', 35),
new Person('Linda', 25),
new Person('Peter', 45)]
assert [['Linda', 25], ['Daniel', 35]] ==
people
.findAll { p -> p.age < 40 }
.sort { p -> p.age }
.collect { p -> [p.name, p.age] }
• Map, filter,
reduce style
using Closures

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Language Integrated Query Motivation
assert [['Linda', 25], ['Daniel', 35]] ==
people.stream()
.filter(p -> p.age < 40)
.sorted((p1, p2) -> p1.age <=> p2.age)
.map(p -> [p.name, p.age])
.toList()
• Map, filter, reduce style
using lambdas/streams

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Language Integrated Query
assert [['Linda', 25], ['Daniel', 35]] == GQ {
from p in people
where p.age < 40
orderby p.age
select p.name, p.age
}.toList()

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GINQ

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Language Integrated Query: JSON example
import groovy.json.JsonSlurper
def json = new JsonSlurper().parseText('''
{
"prices": [
{"name": "Kakuda plum", "price": 13},
{"name": "Camu camu", "price": 25},
{"name": "Acerola cherries", "price": 39},
{"name": "Guava", "price": 2.5},
{"name": "Kiwifruit", "price": 0.4},
{"name": "Orange", "price": 0.4}
],
"vitC": [
{"name": "Kakuda plum", "conc": 5300},
{"name": "Camu camu", "conc": 2800},
{"name": "Acerola cherries", "conc": 1677},
{"name": "Guava", "conc": 228},
{"name": "Kiwifruit", "conc": 144},
{"name": "Orange", "conc": 53}
]
}
''')

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Language Integrated Query: JSON example
import groovy.json.JsonSlurper
def json = new JsonSlurper().parseText('''
{
"prices": [
{"name": "Kakuda plum", "price": 13},
{"name": "Camu camu", "price": 25},
{"name": "Acerola cherries", "price": 39},
{"name": "Guava", "price": 2.5},
{"name": "Kiwifruit", "price": 0.4},
{"name": "Orange", "price": 0.4}
],
"vitC": [
{"name": "Kakuda plum", "conc": 5300},
{"name": "Camu camu", "conc": 2800},
{"name": "Acerola cherries", "conc": 1677},
{"name": "Guava", "conc": 228},
{"name": "Kiwifruit", "conc": 144},
{"name": "Orange", "conc": 53}
]
}
''')
assert GQ {
from p in json.prices
join c in json.vitC on c.name == p.name
orderby c.conc / p.price in desc
limit 2
select p.name
}.toList() == ['Kakuda plum', 'Kiwifruit']

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Language Integrated Query: XML example
import groovy.xml.XmlSlurper
def root = new XmlSlurper().parseText('''

13
25
39
2.5
0.4
0.4

5300
2800
1677
228
144
53

''')

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Language Integrated Query: XML example
import groovy.xml.XmlSlurper
def root = new XmlSlurper().parseText('''

13
25
39
2.5
0.4
0.4

5300
2800
1677
228
144
53

''')
assert GQ {
from p in root.prices.price
join c in root.vitaminC.conc on [email protected] == [email protected]
orderby c.toInteger() / p.toDouble() in desc
limit 2
select [email protected]

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Language Integrated Query: SQL example
// ... create sql connection ...
def price = sql.rows('SELECT * FROM Price')
def vitC = sql.rows('SELECT * FROM VitaminC')
assert GQ {
from p in price
join c in vitC on c.name == p.name
orderby c.per100g / p.per100g in desc
limit 2
select p.name
// ... close connection ...

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Type Annotations
• Existing support
• Now supported
@Grab('net.jqwik:jqwik:1.6.5')
import net.jqwik.api.*
import net.jqwik.api.constraints.*
class PropertyBasedTests {
@Property
def uniqueInList(@ForAll @Size(5) @UniqueElements List aList) {
assert aList.size() == aList.toSet().size()
assert aList.every{ anInt -> anInt >= 0 && anInt <= 10 }
}
}

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Type Annotations
@Grab('org.hibernate.validator:hibernate-validator:7.0.1.Final')
@Grab('org.hibernate.validator:hibernate-validator-cdi:7.0.1.Final')
@Grab('org.glassfish:jakarta.el:4.0.0')
import jakarta.validation.constraints.*
import jakarta.validation.*
import groovy.transform.*
@Canonical
class Car {
@NotNull @Size(min = 2, max = 14) String make
@Min(1L) int seats
List owners
}
def validator = Validation.buildDefaultValidatorFactory().validator
def violations = validator.validate(new Car(make: 'T', seats: 1))
assert violations*.message == ['size must be between 2 and 14']
violations = validator.validate(new Car(make: 'Tesla', owners: ['']))
assert violations*.message.toSet() == ['must be greater than or equal to 1', 'must not be blank'] as Set
violations = validator.validate(new Car(make: 'Tesla', owners: ['Elon'], seats: 2))
assert !violations

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• Module changes
Language Features
Libraries/Tooling
• JavaShell
• Improved ranges
AST transforms
• @POJO
• @RecordType
GDK enhancements
Groovy 4 - Summary

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Built-in type checkers: regex checker
def newYearsEve = '2020-12-31'
def matcher = newYearsEve =~ /(\d{4})-(\d{1,2})-(\d{1,2}/ // ???

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def matcher = newYearsEve =~ /(\d{4})-(\d{1,2})-(\d{1,2}/ // PatternSyntaxException

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import groovy.transform.TypeChecked
@TypeChecked(extensions = 'groovy.typecheckers.RegexChecker')
def whenIs2020Over() {
def matcher = newYearsEve =~ /(\d{4})-(\d{1,2})-(\d{1,2}/
}
def matcher = newYearsEve =~ /(\d{4})-(\d{1,2})-(\d{1,2}/ // PatternSyntaxException

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~/\w{3/ // missing closing repetition quantifier brace
~"(.)o(.*" // missing closing group bracket
Pattern.compile(/?/) // dangling meta character '?' (Java longhand)
'foobar' =~ /f[o]{2/ // missing closing repetition quantifier brace
'foobar' ==~ /(foo/ // missing closing group bracket
Pattern.matches(/?/, 'foo') // dangling meta character '?' (Java longhand)
def m = 'foobar' =~ /(...)(...)/
assert m[0][1] == 'foo' // okay
assert m[0][3] // type error: only two groups in regex
Pattern p = Pattern.compile('(...)(...)')
Matcher m = p.matcher('foobar')
assert m.find()
assert m.group(1) == 'foo' // okay
assert m.group(3) // type error: only two groups in regex

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Built-in macro methods: SV, SVI, SVD, NV, NVL
def num = 42
def list = [1 ,2, 3]
def range = 0..5
def string = 'foo'
println SV(num, list, range, string)
println SVI(range)
println SVD(range)
num=42, list=[1, 2, 3], range=[0, 1, 2, 3, 4, 5], string=foo
range=0..5
range=inclusiveRight=true inclusiveLeft=true
def r = NV(range)
assert r instanceof NamedValue
assert r.name == 'range' && r.val == 0..5

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TOML Builder/Slurper Incubating
def ts = new TomlSlurper()
def toml = ts.parseText(builder.toString())
assert 'HSV Maloo' == toml.records.car.name
assert 'Holden' == toml.records.car.make
assert 2006 == toml.records.car.year
assert 'Australia' == toml.records.car.country
assert 'http://example.org' == toml.records.car.homepage
assert 'speed' == toml.records.car.record.type
assert 'production pickup truck 271kph' == toml.records.car.record.description
def builder = new TomlBuilder()
builder.records {
car {
name 'HSV Maloo'
make 'Holden'
year 2006
country 'Australia'
homepage new URL('http://example.org')
record {
type 'speed'
description 'production pickup truck 271kph'
}
}
}

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JavaShell
import org.apache.groovy.util.JavaShell
def opts = ['--enable-preview', '--release', '14']
def src = 'record Coord(int x, int y) {}'
Class coordClass = new JavaShell().compile('Coord', opts, src)
assert coordClass.newInstance(5, 10).toString() == 'Coord[x=5, y=10]'

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Improved Ranges
def range = 1..5
assert range == [1, 2, 3, 4, 5]
range = 1..<5
assert range == [1, 2, 3, 4]
range = 1assert range == [2, 3, 4, 5]
range = 1assert range == [2, 3, 4]
• Existing
support
• Now
supported

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• Module changes
Language Features
Libraries/Tooling
• JavaShell
• Improved ranges
AST transforms
• @POJO
• @RecordType
GDK enhancements
Groovy 4 - Summary

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AST Transformations
class Book {
List authors
String title
Date publicationDate
}

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AST Transformations
class Book {
List authors
String title
}
public class Book implements GroovyObject {
private java.util.List authors
private java.lang.String title
private java.util.Date publicationDate
public java.util.List getAuthors() { ... }
public void setAuthors(java.util.List value) { ... }
public java.lang.String getTitle() { ... }
public void setTitle(java.lang.String value) { ... }
public java.util.Date getPublicationDate() { ... }
public void setPublicationDate(java.util.Date value) { ... }
}

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AST Transformations
@ToString
class Book {
List authors
String title
}

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AST Transformations
@ToString
class Book {
List authors
String title
}
public class Book implements GroovyObject {
private java.util.List authors
private java.lang.String title
private java.util.Date publicationDate
public java.util.List getAuthors() { ... }
public void setAuthors(java.util.List value) { ... }
public java.lang.String getTitle() { ... }
public void setTitle(java.lang.String value) { ... }
public java.util.Date getPublicationDate() { ... }
public void setPublicationDate(java.util.Date value) { ... }
public java.lang.String toString() {
/* build toString based on properties */
}
}

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AST Transformations
@Immutable(copyWith = true)
@Sortable(excludes = 'authors')
@AutoExternalize
class Book {
@IndexedProperty
List authors
String title
}

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AST Transformations
// imports not shown
public class Book {
private String $to$string;
private int $hash$code;
private final List authors;
private final String title;
private final Date publicationDate;
private static final java.util.Comparator this$TitleComparator;
private static final java.util.Comparator this$PublicationDateComparator;
public Book(List authors, String title, Date publicationDate) {
if (authors == null) {
this.authors = null;
} else {
if (authors instanceof Cloneable) {
List authorsCopy = (List) ((ArrayList>) authors).clone();
this.authors = (List) (authorsCopy instanceof SortedSet ? DefaultGroovyMethods.asImmutable(authorsCopy)
: authorsCopy instanceof SortedMap ? DefaultGroovyMethods.asImmutable(authorsCopy)
: authorsCopy instanceof Set ? DefaultGroovyMethods.asImmutable(authorsCopy)
: authorsCopy instanceof Map ? DefaultGroovyMethods.asImmutable(authorsCopy)
: authorsCopy instanceof List ? DefaultGroovyMethods.asImmutable(authorsCopy)
: DefaultGroovyMethods.asImmutable(authorsCopy));
} else {
this.authors = (List) (authors instanceof SortedSet ? DefaultGroovyMethods.asImmutable(authors)
: authors instanceof SortedMap ? DefaultGroovyMethods.asImmutable(authors)
: authors instanceof Set ? DefaultGroovyMethods.asImmutable(authors)
: authors instanceof Map ? DefaultGroovyMethods.asImmutable(authors)
: authors instanceof List ? DefaultGroovyMethods.asImmutable(authors)
: DefaultGroovyMethods.asImmutable(authors));
}
}
this.title= title;
if (publicationDate== null) {
this.publicationDate= null;
} else {
this.publicationDate= (Date) publicationDate.clone();
}
}
public Book(Map args) {
if ( args == null) {
args = new HashMap();
}
ImmutableASTTransformation.checkPropNames(this, args);
if (args.containsKey("authors")) {
if ( args.get("authors") == null) {
this .authors = null;
} else {
if (args.get("authors") instanceof Cloneable) {
List authorsCopy = (List) ((ArrayList>) args.get("authors")).clone();
this.authors = (List) (authorsCopy instanceof SortedSet ? DefaultGroovyMethods.asImmutable(authorsCopy)
: authorsCopy instanceof SortedMap ? DefaultGroovyMethods.asImmutable(authorsCopy)
: authorsCopy instanceof Set ? DefaultGroovyMethods.asImmutable(authorsCopy)
: authorsCopy instanceof Map ? DefaultGroovyMethods.asImmutable(authorsCopy)
: authorsCopy instanceof List ? DefaultGroovyMethods.asImmutable(authorsCopy)
: DefaultGroovyMethods.asImmutable(authorsCopy));
} else {
List authors = (List) args.get("authors");
this.authors = (List) (authors instanceof SortedSet ? DefaultGroovyMethods.asImmutable(authors)
: authors instanceof SortedMap ? DefaultGroovyMethods.asImmutable(authors)
: authors instanceof Set ? DefaultGroovyMethods.asImmutable(authors)
: authors instanceof Map ? DefaultGroovyMethods.asImmutable(authors)
: authors instanceof List ? DefaultGroovyMethods.asImmutable(authors)
: DefaultGroovyMethods.asImmutable(authors));
}
}
} else {
this .authors = null;
}
if (args.containsKey("title")) {this .title = (String) args.get("title"); } else { this .title = null;}
if (args.containsKey("publicationDate")) {
if (args.get("publicationDate") == null) {
this.publicationDate = null;
} else {
this.publicationDate = (Date) ((Date) args.get("publicationDate")).clone();
}
} else {this.publicationDate = null; }
}
…
public Book() {
this (new HashMap());
}
public int compareTo(Book other) {
if (this == other) {
return 0;
}
Integer value = 0
value = this .title <=> other .title
if ( value != 0) {
return value
}
value = this .publicationDate <=> other .publicationDate
if ( value != 0) {
return value
}
return 0
}
public static Comparator comparatorByTitle() {
return this$TitleComparator;
}
public static Comparator comparatorByPublicationDate() {
return this$PublicationDateComparator;
}
public String toString() {
StringBuilder _result = new StringBuilder();
boolean $toStringFirst= true;
_result.append("Book(");
if ($toStringFirst) {
$toStringFirst = false;
} else {
_result.append(", ");
}
_result.append(InvokerHelper.toString(this.getAuthors()));
} else {
}
_result.append(InvokerHelper.toString(this.getTitle()));
} else {
}
_result.append(InvokerHelper.toString(this.getPublicationDate()));
_result.append(")");
if ($to$string == null) {
$to$string = _result.toString();
}
return $to$string;
}
public int hashCode() {
if ( $hash$code == 0) {
int _result = HashCodeHelper.initHash();
if (!(this.getAuthors().equals(this))) {
_result = HashCodeHelper.updateHash(_result, this.getAuthors());
}
if (!(this.getTitle().equals(this))) {
_result = HashCodeHelper.updateHash(_result, this.getTitle());
}
if (!(this.getPublicationDate().equals(this))) {
_result = HashCodeHelper.updateHash(_result, this.getPublicationDate());
}
$hash$code = (int) _result;
}
return $hash$code;
}
public boolean canEqual(Object other) {
return other instanceof Book;
}
…
public boolean equals(Object other) {
if ( other == null) {
return false;
}
if (this == other) {
return true;
}
if (!( other instanceof Book)) {
return false;
}
Book otherTyped = (Book) other;
if (!(otherTyped.canEqual( this ))) {
return false;
}
if (!(this.getAuthors() == otherTyped.getAuthors())) {
return false;
}
if (!(this.getTitle().equals(otherTyped.getTitle()))) {
return false;
}
if (!(this.getPublicationDate().equals(otherTyped.getPublicationDate()))) {
return false;
}
return true;
}
public final Book copyWith(Map map) {
if (map == null || map.size() == 0) {
return this;
}
Boolean dirty = false;
HashMap construct = new HashMap();
if (map.containsKey("authors")) {
Object newValue = map.get("authors");
Object oldValue = this.getAuthors();
if (newValue != oldValue) {
oldValue= newValue;
dirty = true;
}
construct.put("authors", oldValue);
} else {
construct.put("authors", this.getAuthors());
}
if (map.containsKey("title")) {
Object newValue = map.get("title");
Object oldValue = this.getTitle();
oldValue= newValue;
dirty = true;
}
construct.put("title", oldValue);
} else {
construct.put("title", this.getTitle());
}
if (map.containsKey("publicationDate")) {
Object newValue = map.get("publicationDate");
Object oldValue = this.getPublicationDate();
oldValue= newValue;
dirty = true;
}
construct.put("publicationDate", oldValue);
} else {
construct.put("publicationDate", this.getPublicationDate());
}
return dirty == true ? new Book(construct) : this;
}
public void writeExternal(ObjectOutputout) throws IOException {
out.writeObject(authors);
out.writeObject(title);
out.writeObject(publicationDate);
}
public void readExternal(ObjectInputoin) throws IOException, ClassNotFoundException{
authors = (List) oin.readObject();
title = (String) oin.readObject();
publicationDate= (Date) oin.readObject();
}
…
static {
this$TitleComparator = new Book$TitleComparator();
this$PublicationDateComparator = new Book$PublicationDateComparator();
}
public String getAuthors(int index) {
return authors.get(index);
}
public List getAuthors() {
return authors;
}
public final String getTitle() {
return title;
}
public final Date getPublicationDate() {
if (publicationDate== null) {
return publicationDate;
} else {
return (Date) publicationDate.clone();
}
}
public int compare(java.lang.Objectparam0, java.lang.Objectparam1) {
return -1;
}
private static class Book$TitleComparator extends AbstractComparator {
public Book$TitleComparator() {
}
public int compare(Book arg0, Book arg1) {
if (arg0 == arg1) {
return 0;
}
if (arg0 != null && arg1 == null) {
return -1;
}
if (arg0 == null && arg1 != null) {
return 1;
}
return arg0.title <=> arg1.title;
}
return -1;
}
}
private static class Book$PublicationDateComparator extends AbstractComparator {
public Book$PublicationDateComparator() {
}
public int compare(Book arg0, Book arg1) {
if ( arg0 == arg1 ) {
return 0;
}
if ( arg0 != null && arg1 == null) {
return -1;
}
if ( arg0 == null && arg1 != null) {
return 1;
}
return arg0 .publicationDate <=> arg1 .publicationDate;
}
return -1;
}
}
}
@Immutable(copyWith = true)
@Sortable(excludes = 'authors')
@AutoExternalize
class Book {
@IndexedProperty
List authors
String title
}

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AST Transformations: Groovy 2.4, Groovy 2.5, Groovy 3.0, Groovy 4.0*
* Now also
priorities for
AST transforms
in the same phase

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AST Transformations: Groovy 2.4, Groovy 2.5, Groovy 3.0, Groovy 4.0
@NonSealed
@RecordBase
@Sealed
@PlatformLog
@GQ
@Final
@RecordType
@POJO
@Pure
@Contracted
@Ensures
@Invariant
@Requires
@ClassInvariant
@ContractElement
@Postcondition
@Precondition
(Improved in 2.5)

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Groovy 2.5: AST Transforms: @Immutable becomes meta-annotation
@Immutable
class Point {
int x, y
}
@ToString(includeSuperProperties = true, cache = true)
@EqualsAndHashCode(cache = true)
@ImmutableBase
@ImmutableOptions
@PropertyOptions(propertyHandler = ImmutablePropertyHandler)
@TupleConstructor(defaults = false)
@MapConstructor(noArg = true, includeSuperProperties = true, includeFields = true)
@KnownImmutable
class Point {
int x, y
}

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Records revisited (@RecordType meta-annotation)
record Point(int x, y){ }
@RecordBase
// RecordBase makes implicit changes equivalent to native
// toString(), equals() and hashCode() record implements or:
// @ToString(cache = false, includeNames = true, includePackage = false,
// leftDelimiter = '[', rightDelimiter = ']', pojo = true,
// nameValueSeparator = '=', fieldSeparator = ", ")
// @EqualsAndHashCode(useCanEqual = false, pojo = true)
@RecordOptions
@TupleConstructor(namedVariant = true, force = true, defaultsMode = AUTO)
@PropertyOptions
@KnownImmutable
@POJO
@CompileStatic
class Point {
int x, y
}
@RecordType
class Point {
int x, y
}

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Declarative Record Customization
def a = new Agenda(topics: ['Sealed', 'Records'])
assert a.topics().size() == 2
assert a.toString() == 'Agenda[topics=[Sealed, Records]]'
a.topics().clear()
a.topics() << 'Switch Expressions'
record Agenda(List topics) { }

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Declarative Record Customization
def a = new Agenda(topics: ['Sealed', 'Records'])
shouldFail(UnsupportedOperationException) {
a.topics().clear()
}
assert a.toString() == 'Agenda([Sealed, Records])'
@ToString
@PropertyOptions(propertyHandler = ImmutablePropertyHandler)
record Agenda(List topics) { }

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@POJO
3
true
Point(x:1, y:3)
Point(x:2, y:2)
Point(x:3, y:1)
2
Incubating

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groovy-contracts module
Design-by-contract import groovy.contracts.*
@Invariant({ speed() >= 0 })
class Rocket {
int speed = 0
boolean started = true
@Requires({ isStarted() })
@Ensures({ old.speed < speed })
def accelerate(inc) { speed += inc }
def isStarted() { started }
def speed() { speed }
}
def r = new Rocket()
r.accelerate(5)

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groovy-contracts module
Design-by-contract abstract class Material {
@Requires({ color != null })
String toString() {
"${getClass().name} with color ${color.toLowerCase()}"
}
}
new Glass().toString() // PreconditionViolation
• Alternative way
to harden earlier
sealed example

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• Module changes
Language Features
Libraries/Tooling
• JavaShell
• Improved ranges
AST transforms
• @POJO
• @RecordType
GDK enhancements
Groovy 4 - Summary

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GDK Enhancements
assert (Stream.of(1) + Stream.of(2)).toList() == [1,2]
println Runtime.runtime.pid

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On-going research for future Groovy versions
• Additional switch destructuring/pattern matching
• instanceof “pattern matching”
• Smarter type checking: non-null, pure
• Module definitions in Groovy
• Syntactic sugar wrapper for JDK11 HttpClient

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Join us:
groovy.apache.org

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Groovy Roadmap

Groovy Roadmap

paulking

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