Programmers rejoice: QML makes business people understand. Qt Developer Days 2014 Hinrich Specht 2. September 2014 Folie 1

Transcription

1 Programmers rejoice: QML makes business people understand Qt Developer Days 2014 Hinrich Specht 2. September 2014 Folie 1

2 About me My company What I do at work Where I live

3 What is it all about? Agenda Motivation A real life example The hurdles of DSL creation What Qt has to offer PresentationSystem demo Extending Qml s type system When to use Qml for DSL creation and when not Qt Developer Days 2014 Hinrich Specht 2. September 2014 Folie 3

4 A common problem in software development You mean If(obj!= NULL) { name= Qt }? #?=&f\ (%) Qt Developer Days 2014 Hinrich Specht 25. September 2014 Folie 4

5 What if Stakeholders and developers could share a common language? changes to the software could be made in that language, too? Qt Developer Days 2014 Hinrich Specht 2. September 2014 Folie 5

6 A real life example Qt Developer Days 2014 Hinirch Specht 2. September 2014 Folie 6

7 The heating system example. Before. Implementation Build & Deploy Adjust requirements Up to 4 weeks, only in winter Rollout to test site Gather data Qt Developer Days 2014 Hinrich Specht 25. September 2014 Folie 7

8 The heating system example. After. Adjust software via DSL Cont.Integration Adjust requirements < 1 week Rollout to test site Gather data Qt Developer Days 2014 Hinrich Specht 25. September 2014 Folie 8

9 Why... isn t there a DSL in every software project? Qt Developer Days 2014 Hinrich Specht 25. September 2014 Folie 9

10 DSLs are hard to develop Formal definition Grammar Schema Metamodel Abstract Syntax Tooling Parser Validator Compiler Editor / IDE Qt Developer Days 2014 Hinrich Specht 2. September 2014 Folie 10

11 DSL creation with XText XText is a powerful, DSL-based language development framework Steps to create a DSL using Xtext: Textual definition of syntax and semantic model for your DSL. Language: Grammar Configure generator that creates java packages and editor for your DSL. Language: MWE2 Set up Maven builds for CI of your DSL Update Eclipse Use your DSL Not targeting Java? Use Xtend for code generation Qt Developer Days 2014 Hinrich Specht 2. September 2014 Folie 11

12 Programming languages compared Comes with an extensible type system! QML, WPF, Silverlight Object oriented, declarative, special purpose, Model driven C++, Java, C# Object oriented, imperative,general purpose C, COBOL Procedure oriented, imperative Assembler Code Processor instruction set, no abstraction at all Qt Developer Days 2014 Hinrich Specht 25. September 2014 Folie 12

13 DSL creation with Qml what Qt has to offer Custom types can be made available in Qml Types used are backed by C++ classes CodeCompletion for custom types immediately available in Creator Easy to learn Effort needed to create a (simple) DSL is low No other programming languages needed! Qt Developer Days 2014 Hinrich Specht 2. September 2014 Folie 13

14 Extending the Qml type system Any custom types can be registered with QML s type system (but must inherit from QObject) Different forms of registration are available to define the runtime behaviour of your types: Creatable types Uncreatable types Interfaces Singletons Qt Developer Days 2014 Hinrich Specht 2. September 2014 Folie 14

15 The QmlPresentationSystem is a DSL for creating slide decks makes use of QML s extensible type system is easy to use (compared to programming a slide deck with C++ or any other general purpose language) Qt Developer Days 2014 Hinrich Specht 2. September 2014 Folie 15

16 How to use your own custom types in Qml 1. Derive from QObject Public class YourType : public Qobject { } 2. Define Properties Q_PROPERTY(DataElementIds::EnDataElementIds identifier READ getidentifier MEMBER m_id) 3. Register type in Qml qmlregistertype<yourtype>("com.your.namespace", 1, 0, QmlTypeName"); Qt Developer Days 2014 Hinrich Specht 2. September 2014 Folie 16

17 How to use your own custom types in Qml 5. Run qmake 4. Import custom namespace in Qml file import com.your.namespace Ready to use custom type in Qml YourType{ displayname: YourInstanceName" value: false identifier: YourId } Qt Developer Days 2014 Hinrich Specht 2. September 2014 Folie 17

18 Using singleton types QObject and QJSValue types can be registered as singleton types. Registering types that are defined in C++: int qmlregistersingletontype(const char * uri, int versionmajor, int versionminor, const char * typename, QJSValue(* ) ( QQmlEngine *, QJSEngine * ) callback) int qmlregistersingletontype(const char * uri, int versionmajor, int versionminor, const char * typename, QObject *(* ) ( QQmlEngine *, QJSEngine * ) callback) Qt Developer Days 2014 Hinrich Specht 2. September 2014 Folie 18

19 Using singleton types Registering types that are defined in Qml: int qmlregistersingletontype(const QUrl & url, const char * uri, int versionmajor, intversionminor, const char * qmlname) Qt Developer Days 2014 Hinrich Specht 2. September 2014 Folie 19

20 Using uncreatable types int qmlregisteruncreatabletype(const char * uri, int versionmajor, int versionminor, const char * qmlname, const QString & message) Note: To use enums in Qml, they must be wrapped in a class. Qt Developer Days 2014 Hinrich Specht 2. September 2014 Folie 20

21 Drawbacks you have to deal with Mingling with QtQuick types and QObject properties No integrated code generator for creation of non-qt-code Editor is not always as smart as it could be Fixed syntax Qt Developer Days 2014 Hinrich Specht 2. September 2014 Folie 21

22 See how it works Qt Developer Days 2014 Hinrich Specht 2. September 2014 Folie 22

23 The sample application DataLayer DataElements DataSwitch GpioMappings HardwareLayer GPIOs Qt Developer Days 2014 Hinrich Specht 2. September 2014 Folie 23

24 When is a Qml based DSL the right choice? Qt Developer Days 2014 Hinrich Specht 2. September 2014 Folie 24

25 What is a domain? Stakeholders domains Your domains Heating system System composition Drive control StateMachines Accounting UIs Routing Data layer Simply said: Everything is a domain Qt Developer Days 2014 Hinrich Specht 25. September 2014 Folie 25

26 Think about a QML based DSL, when other tools would require too much effort simple DSL features are needed no code generation is required the DSL will mainly be used to define static aspects Qt Developer Days 2014 Hinrich Specht 25. September 2014 Folie 26

27 Think about using other tools when you want your own syntax / semantics code generation for different languages is required when you want to have a clean DSL (without artifacts from QObject) Qt Developer Days 2014 Hinrich Specht 25. September 2014 Folie 27

28 Q&A / Discussion Qt Developer Days 2014 Hinrich Specht 2. September 2014 Folie 28