This document discusses using Gradle for building projects in multiple languages. Gradle's domain specific language is based on Groovy, which allows for concise syntax. Gradle supports building Java, C++, Ruby, and other languages through plugins. It can also be used to build documentation and publish artifacts to repositories. Migrating from other build systems like Ant, Maven, and Make to Gradle is also discussed.

1. GRADLE IN A POLYGLOT WORLD
Schalk Cronjé

2. ABOUT ME
Email:
Twitter / Ello : @ysb33r
ysb33r@gmail.com
Gradle plugins authored/contributed to: VFS, Asciidoctor,
JRuby family (base, jar, war etc.), GnuMake, Doxygen

3. GRADLE
Not just for building JVM projects

4. GRADLE DSL
Underlying language is Groovy
You don’t need to be a Groovy expert to be a Gradle
power user
Groovy doesn’t need ; in most cases
Groovy does more with less punctuation, making it an
ideal choice for a DSL
In most cases lines that do not end on an operator is
considered a completed statement.

5. GROOVY VS JAVA
In Groovy:
All class members are public by default
No need to create getters/setters for public fields
Both static & dynamic typing supported
def means Object

6. CALLING METHODS
class Foo {
void bar( def a,def b ) {}
}
def foo = new Foo()
foo.bar( '123',456 )
foo.bar '123', 456
foo.with {
bar '123', 456
}

7. CALLING METHODS WITH CLOSURES
class Foo {
void bar( def a,Closure b ) {}
}
def foo = new Foo()
foo.bar( '123',{ println it } )
foo.bar ('123') {
println it
}
foo.bar '123', {
println it
}

8. MAPS IN GROOVY
Hashmaps in Groovy are simple to use
def myMap = [ plugin : 'java' ]
Maps are easy to pass inline to functions
project.apply( plugin : 'java' )
Which in Gradle can become
apply plugin : 'java'

9. LISTS IN GROOVY
Lists in Groovy are simple too
def myList = [ 'clone', ''http://github.com/ysb33r/GradleLectures' ]
This makes it possible for Gradle to do
args 'clone', 'http://github.com/ysb33r/GradleLectures'

10. CLOSURE DELEGATION IN GROOVY
When a symbol cannot be resolved within a closure,
Groovy will look elsewhere
In Groovy speak this is called a Delegate.
This can be programmatically controlled via the
Closure.delegate property.

11. CLOSURE DELEGATION IN GROOVY
class Foo {
def target
}
class Bar {
Foo foo = new Foo()
void doSomething( Closure c ) {
c.delegate = foo
c()
}
}
Bar bar = new Bar()
bar.doSomething {
target = 10
}

12. MORE CLOSURE MAGIC
If a Groovy class has a method 'call(Closure)`, the object can
be passed a closure directly.
class Foo {
def call( Closure c) { /* ... */ }
}
Foo foo = new Foo()
foo {
println 'Hello, world'
}
// This avoids ugly syntax
foo.call({ println 'Hello, world' })

13. CLOSURE DELEGATION IN GRADLE
In most cases the delegation will be entity the closure is
passed to.
Will also look at the Project and ext objects.
The Closure.delegate property allows plugin writers
ability to create beautiful DSLs
task runSomething(type : Exec ) { cmdline 'git' }
is roughly the equivalent of
ExecTask runSomething = new ExecTask()
runSomething.cmdline( 'git' )

14. GRADLE TASKS
Can be based upon a task type
task runSomething ( type : Exec ) {
command 'git'
args 'clone', 'https://bitbucket.com/ysb33r/GradleWorkshop'
}
Can be free-form
task hellowWorld << {
println 'Hello, world'
}

15. GRADLE TASKS : CONFIGURATION VS
ACTION
Use of << {} adds action to be executed
Tasks supplied by plugin will have default actions
Use of {} configures a task

16. BUILDSCRIPT
The buildscript closure is special
It tells Gradle what to load into the classpath before
evaluating the script itself.
It also tells it where to look for those dependencies.
Even though Gradle 2.1 has added a new way of adding
external plugins, buildscript are much more flexible.

17. EXTENSIONS
Extensions are global configuration blocks added by
plugins.
Example: The jruby-gradle-base plugin will add a
jruby block.
apply plugin: 'com.github.jruby-gradle.base'
jruby {
defaultVersion = '1.7.11'
}

18. JAVA PROJECT
repositories {
jcenter()
}
apply plugin : 'java'
dependencies {
testCompile 'junit:junit:4.1+'
}

19. GRADLE DEPENDENCY
MANAGEMENT
Easy to use
Flexible to configure for exceptions
Uses dependencies closure
First word on line is usually name of a configuration.
Configurations are usually supplied by plugins.
Dependencies are downloaded from repositories
Maven coordinates are used as format

20. GRADLE REPOSITORIES
Specified within a repositories closure
Processed in listed order to look for dependencies
jcenter() preferred open-source repo.
mavenLocal(), mavenCentral(), maven {}
Ivy repositories via ivy {}
Flat-directory repositories via flatDir

21. BUILDING C++

22. BUILDING C++ - TOOL SUPPORT
Operating
System
Tool Chain Official
Linux gcc, clang Y
MacOS X Xcode Y
gcc-macports, clang-
macports
N
Windows Visual C++, gcc-cygwin32,
gcc-mingw
Y

23. gcc-cygwin64 N
Unix-like gcc, clang N

24. BUILDING C++ - LAYOUT
Need to change convention from traditional C++ projects
.cpp files go in src/${name}/cpp
Exported headers files go in src/${name}/headers
Local header files should be in src/${name}/cpp
Object files will end up in ${buildDir}/objs
Binary files will end up in ${buildDir}/binaries

25. BUILDING C++ - BASICS
apply plugin : 'cpp'

26. BUILDING C++ - EXECUTABLE
model {
components {
hello(NativeExecutableSpec)
}
}

27. BUILDING C++ - PROJECT LAYOUT
├── build.gradle
└── src
└─── hello
├── cpp
│ └─── hello.cpp
│
└── headers
└─── hello.hpp

28. BUILDING C++ - EXISTING PROJECTS
Source directories can be adjusted
Alternative compiler locations

29. BUILDING C++ - ALTERNATIVE
SOURCE
sources {
cpp {
source {
srcDir "myDir"
include "**/*.cpp"
}
}
}

30. BUILDING C++ - OTHER FEATURES
Cross compilation
Multi-architecture targets
Set compiler & linker flags
Multi-variant builds

31. BUILDING C++ - WEAKNESS
Currently only have built-in support for CUnit
Only platform configuration tool support is CMake
No Autotools equivalent
DSL can be slicker

32. BUILDING RUBY

33. BUILDING JRUBY
buildscript {
repositories {
jcenter()
maven { url "https://plugins.gradle.org/m2/" }
}
dependencies {
classpath 'com.github.jruby-gradle:jruby-gradle-plugin:1.1.4'
}
}
import com.github.jrubygradle.JRubyExec

34. BUILDING JRUBY
apply plugin: "com.github.jruby-gradle.base"
dependencies {
jrubyExec "rubygems:colorize:0.7.7+"
}
task printSomePrettyOutputPlease(type: JRubyExec) {
description "Execute our nice local print-script.rb"
script "${projectDir}/print-script.rb"
}
(Example from JRuby-Gradle project)

35. OTHER LANGUAGES
C / ASM / Resources (built-in)
Clojure (plugin)
Frege (plugin)
Golang (plugin)
Scala (built-in)
Gosu (plugin)

36. SUPPORT FOR OTHER
BUILDSYSTEMS
ANT (built-in)
GNU Make
MSBuild / xBuild
Grunt
Anything else craftable via Exec or JavaExec task

37. DOCUMENTATION

38. BUILDING DOCUMENTATION
Doxygen
Markdown
Asciidoctor

39. ASCIIDOCTOR

40. BUILDING WITH ASCIIDOCTOR
plugins {
id 'org.asciidoctor.convert' version '1.5.2'
}

41. BUILDING WITH ASCIIDOCTOR
repositories {
jcenter()
}
asciidoctor {
sources {
include 'example.adoc'
}
backends 'html5'
}

42. BUILDING WITH DOXYGEN
plugins {
id "org.ysb33r.doxygen" version "0.2"
}
doxygen {
source file('src/hello/cpp')
source file('src/hello/headers')
generate_xml true
generate_html true
file_patterns '*.cpp', '*.hpp'
html_colorstyle_sat 100
}

43. PUBLISHING
Built-in to Maven, Ivy
Metadata publishing for native projects still lacking
Various plugins for AWS and other cloud storage
Plain old copies to FTP, SFTP etc.

44. PUBLISHING VIA VFS
plugins {
id "org.ysb33r.vfs" version "1.0-beta3"
}
task publishToWebserver {
vfs {
cp "${buildDir}/website",
"ftp://${username}:${password}@int.someserver.com/var/www",
recursive : true, overwrite : true
}
}

45. MORE SUPPORT…​
Official buildsystem for Android
Docker
Hadoop

46. ENDGAME
Gradle is breaking new ground
Ever improving native support
Continuous performance improvements
Go find some more plugins at https://plugins.gradle.org

47. ABOUT THIS PRESENTATION
Written in Asciidoctor
Styled by asciidoctor-revealjs extension
Built using:
Gradle
gradle-asciidoctor-plugin
gradle-vfs-plugin
Code snippets tested as part of build
Source code:
https://github.com/ysb33r/GradleLectures/tree/AccuLondon

48. THANK YOU
Email:
Twitter / Ello : @ysb33r
ysb33r@gmail.com
Keep an eye out for https://leanpub.com/idiomaticgradle

49. MIGRATIONS

50. ANT TO GRADLE
Reflect Ant Build into Gradle
ant.importBuild('build.xml')

51. MAVEN TO GRADLE
Go to directory where pom.xml is and type
gradle init --type pom

52. GNUMAKE TO GRADLE
Call current Makefile from Gradle
plugins {
id "org.ysb33r.gnumake" version "1.0.2"
}
import org.ysb33r.gradle.gnumake.GnuMakeBuild
task runMake (type:GnuMakeBuild) {
targets 'build','install'
flags DESTDIR : '/copy/files/here', BUILD_NUMBER : '12345'
}