Aurélien Gâteau

Release month, qpropgen 0.1.1

written on Sunday, December 9, 2018

Continuing on this release month idea started last week, here is a release of another project. Today is the first release of qpropgen, a tool to generate QML-friendly QObject-based C++ classes from class definition files.

I started this project because I did not want to manually define the dozen of properties required to represent a sound in SFXR-Qt, which itself got started because I wanted a sound effect generator for Pixel Wheels. Yes, that's a bit of Yak shaving :)

It works this way: first you define your class and its properties in a yaml file:

class: Person
properties:
    - name: firstName
      type: QString
    - name: lastName
      type: QString
    - name: birthDate
      type: QDateTime

Then you run qpropgen person.yaml. It produces two files: person.h and person.cpp.

This is person.h:

// This file has been generated with qpropgen, any changes made to it will be lost!

#ifndef PERSON_H
#define PERSON_H

#include <QObject>

class Person : public QObject {
    Q_OBJECT

    Q_PROPERTY(QString firstName READ firstName
            WRITE setFirstName
            NOTIFY firstNameChanged
    )

    Q_PROPERTY(QString lastName READ lastName
            WRITE setLastName
            NOTIFY lastNameChanged
    )

    Q_PROPERTY(QDateTime birthDate READ birthDate
            WRITE setBirthDate
            NOTIFY birthDateChanged
    )

public:
    explicit Person(QObject* parent = nullptr);


     QString firstName() const;
     void setFirstName(const QString& value);

     QString lastName() const;
     void setLastName(const QString& value);

     QDateTime birthDate() const;
     void setBirthDate(const QDateTime& value);


signals:

    void firstNameChanged(const QString& firstName);

    void lastNameChanged(const QString& lastName);

    void birthDateChanged(const QDateTime& birthDate);

private:
    QString mFirstName;
    QString mLastName;
    QDateTime mBirthDate;
};

#endif // PERSON_H

And this is person.cpp:

// This file has been generated with qpropgen, any changes made to it will be lost!
#include <person.h>

Person::Person(QObject* parent)
    : QObject(parent) {
}


QString Person::firstName() const {
    return mFirstName;
}
void Person::setFirstName(const QString& value) {

    if (mFirstName == value) {

        return;
    }
    mFirstName = value;
    firstNameChanged(value);
}

QString Person::lastName() const {
    return mLastName;
}
void Person::setLastName(const QString& value) {

    if (mLastName == value) {

        return;
    }
    mLastName = value;
    lastNameChanged(value);
}

QDateTime Person::birthDate() const {
    return mBirthDate;
}
void Person::setBirthDate(const QDateTime& value) {

    if (mBirthDate == value) {

        return;
    }
    mBirthDate = value;
    birthDateChanged(value);
}

qpropgen comes with a CMake file to include in your project. Contributions adding support for other build systems are greatly appreciated :)

There is more to it: you can define read-only properties, make setters and getters virtual and a few other tweaks. You can learn more about qpropgen from the README.

Let me know if you find this tool useful!

This post was tagged pko, qml, qpropgen, qt and release-month
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