Qt utility macro for creating a proper QSettings hierarchy without hassle

settings.h

#ifndef SETTINGS_H
#define SETTINGS_H

#include <QSettings>
#include <QMap>
#include <QObject>
#include <QStringList>

extern QMap<QObject*, QSettings*> _settings_h_settings;

// rev. 2: Use QStringList instead of repeated QString formatting

/**
 * @brief returns a QSettings with a reasonable prefix set
 * @note only works inside methods of QObject-derived classes
 * @note first use should be early and unconditional, e.g. in the constructor
 * @note add definition of _settings_h_settings to one compilation unit
 */
#define settings                                        \
    (*[this]() -> QSettings* {                          \
        if(_settings_h_settings.contains(this)) {       \
            return _settings_h_settings[this];          \
        }                                               \
        QStringList path{this->objectName()};           \
        QObject *p{this->parent()};                     \
        while(p) {                                      \
            if(p->objectName().size()) {                \
            path.prepend(p->objectName());              \
            }                                           \
            p = p->parent();                            \
        }                                               \
        QSettings *s{new QSettings(this)};              \
        s->beginGroup(path.join("/"));                  \
        _settings_h_settings[this] = s;                 \
        return s;                                       \
    }())

#endif // SETTINGS_H