Python: make interpreter configurable

Add settings page to setup python interpreter and use a combo box in the
run configuration to switch between those configured interpreter.

Change-Id: I51014b785ea822ee138d39c788149f1d22901e55
Reviewed-by: Christian Stenger <christian.stenger@qt.io>
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/python/CMakeLists.txt

@@ -1,11 +1,13 @@
 add_qtc_plugin(Python
   PLUGIN_DEPENDS Core QtSupport ProjectExplorer TextEditor
   SOURCES
+    python.qrc
     pythoneditor.cpp pythoneditor.h
     pythonconstants.h
     pythonplugin.cpp pythonplugin.h
     pythonformattoken.h
     pythonhighlighter.cpp pythonhighlighter.h
     pythonindenter.cpp pythonindenter.h
+    pythonsettings.cpp pythonsettings.h
     pythonscanner.cpp pythonscanner.h
 )

src/plugins/python/python.pro

@@ -11,10 +11,15 @@ HEADERS += \
     pythonindenter.h \
     pythonformattoken.h \
     pythonscanner.h \
+    pythonsettings.h
 
 SOURCES += \
     pythonplugin.cpp \
     pythoneditor.cpp \
     pythonhighlighter.cpp \
     pythonindenter.cpp \
-    pythonscanner.cpp
+    pythonscanner.cpp \
+    pythonsettings.cpp
+
+RESOURCES += \
+    python.qrc

src/plugins/python/python.qbs

@@ -14,6 +14,7 @@ QtcPlugin {
     Group {
         name: "General"
         files: [
+            "python.qrc",
             "pythoneditor.cpp", "pythoneditor.h",
             "pythonconstants.h",
             "pythonplugin.cpp", "pythonplugin.h",
@@ -21,6 +22,7 @@ QtcPlugin {
             "pythonindenter.cpp", "pythonindenter.h",
             "pythonformattoken.h",
             "pythonscanner.h", "pythonscanner.cpp",
+            "pythonsettings.cpp", "pythonsettings.h",
         ]
     }
 }

src/plugins/python/python.qrc

@@ -0,0 +1,6 @@
+<RCC>
+    <qresource prefix="/python">
+        <file>images/settingscategory_python.png</file>
+        <file>images/settingscategory_python@2x.png</file>
+    </qresource>
+</RCC>

src/plugins/python/pythonconstants.h

@@ -34,6 +34,9 @@ const char C_PYTHONEDITOR_ID[] = "PythonEditor.PythonEditor";
 const char C_EDITOR_DISPLAY_NAME[] =
         QT_TRANSLATE_NOOP("OpenWith::Editors", "Python Editor");
 
+const char C_PYTHONOPTIONS_PAGE_ID[] = "PythonEditor.OptionsPage";
+const char C_PYTHON_SETTINGS_CATEGORY[] = "P.Python";
+
 /*******************************************************************************
  * MIME type
  ******************************************************************************/

src/plugins/python/pythonplugin.cpp

@@ -27,6 +27,7 @@
 #include "pythoneditor.h"
 #include "pythonconstants.h"
 #include "pythonhighlighter.h"
+#include "pythonsettings.h"
 
 #include <coreplugin/icore.h>
 #include <coreplugin/coreconstants.h>
@@ -56,16 +57,19 @@
 #include <utils/qtcprocess.h>
 #include <utils/utilsicons.h>
 
+#include <QComboBox>
 #include <QDir>
-#include <QRegExp>
-#include <QRegularExpression>
-#include <QRegularExpressionMatch>
-#include <QTextCursor>
+#include <QFormLayout>
+#include <QJsonArray>
 #include <QJsonDocument>
 #include <QJsonObject>
 #include <QJsonParseError>
 #include <QJsonValue>
-#include <QJsonArray>
+#include <QPushButton>
+#include <QRegExp>
+#include <QRegularExpression>
+#include <QRegularExpressionMatch>
+#include <QTextCursor>
 
 using namespace Core;
 using namespace ProjectExplorer;
@@ -217,14 +221,103 @@ private:
 
 ////////////////////////////////////////////////////////////////
 
-class InterpreterAspect : public BaseStringAspect
+class InterpreterAspect : public ProjectConfigurationAspect
 {
     Q_OBJECT
 
 public:
     InterpreterAspect() = default;
+
+    Interpreter currentInterpreter() const;
+    void updateInterpreters(const QList<Interpreter> &interpreters);
+    void setDefaultInterpreter(const Interpreter &interpreter) { m_defaultId = interpreter.id; }
+
+    void fromMap(const QVariantMap &) override;
+    void toMap(QVariantMap &) const override;
+    void addToConfigurationLayout(QFormLayout *layout) override;
+
+private:
+    void updateCurrentInterpreter();
+    void updateComboBox();
+    QList<Interpreter> m_interpreters;
+    QPointer<QComboBox> m_comboBox;
+    QString m_defaultId;
+    QString m_currentId;
 };
 
+Interpreter InterpreterAspect::currentInterpreter() const
+{
+    return m_comboBox ? m_interpreters.value(m_comboBox->currentIndex()) : Interpreter();
+}
+
+void InterpreterAspect::updateInterpreters(const QList<Interpreter> &interpreters)
+{
+    m_interpreters = interpreters;
+    if (m_comboBox)
+        updateComboBox();
+}
+
+void InterpreterAspect::fromMap(const QVariantMap &map)
+{
+    m_currentId = map.value(settingsKey(), m_defaultId).toString();
+}
+
+void InterpreterAspect::toMap(QVariantMap &map) const
+{
+    map.insert(settingsKey(), m_currentId);
+}
+
+void InterpreterAspect::addToConfigurationLayout(QFormLayout *layout)
+{
+    if (QTC_GUARD(m_comboBox.isNull()))
+        m_comboBox = new QComboBox;
+
+    updateComboBox();
+    connect(m_comboBox,
+            &QComboBox::currentTextChanged,
+            this,
+            &InterpreterAspect::updateCurrentInterpreter);
+
+    auto manageButton = new QPushButton(tr("Manage..."));
+    connect(manageButton, &QPushButton::clicked, []() {
+        Core::ICore::showOptionsDialog(Constants::C_PYTHONOPTIONS_PAGE_ID);
+    });
+
+    auto rowLayout = new QHBoxLayout;
+    rowLayout->addWidget(m_comboBox);
+    rowLayout->addWidget(manageButton);
+    layout->addRow(tr("Interpreter"), rowLayout);
+}
+
+void InterpreterAspect::updateCurrentInterpreter()
+{
+    m_currentId = currentInterpreter().id;
+    m_comboBox->setToolTip(currentInterpreter().command.toUserOutput());
+    emit changed();
+}
+
+void InterpreterAspect::updateComboBox()
+{
+    int currentIndex = -1;
+    int defaultIndex = -1;
+    const QString currentId = m_currentId;
+    m_comboBox->clear();
+    for (const Interpreter &interpreter : m_interpreters) {
+        int index = m_comboBox->count();
+        m_comboBox->addItem(interpreter.name);
+        m_comboBox->setItemData(index, interpreter.command.toUserOutput(), Qt::ToolTipRole);
+        if (interpreter.id == currentId)
+            currentIndex = index;
+        if (interpreter.id == m_defaultId)
+            defaultIndex = index;
+    }
+    if (currentIndex >= 0)
+        m_comboBox->setCurrentIndex(currentIndex);
+    else if (defaultIndex >= 0)
+        m_comboBox->setCurrentIndex(defaultIndex);
+    updateCurrentInterpreter();
+}
+
 class MainScriptAspect : public BaseStringAspect
 {
     Q_OBJECT
@@ -251,7 +344,7 @@ private:
     bool supportsDebugger() const { return true; }
     QString mainScript() const { return aspect<MainScriptAspect>()->value(); }
     QString arguments() const { return aspect<ArgumentsAspect>()->arguments(macroExpander()); }
-    QString interpreter() const { return aspect<InterpreterAspect>()->value(); }
+    QString interpreter() const { return aspect<InterpreterAspect>()->currentInterpreter().command.toString(); }
 
     void updateTargetInformation();
 };
@@ -259,15 +352,14 @@ private:
 PythonRunConfiguration::PythonRunConfiguration(Target *target, Core::Id id)
     : RunConfiguration(target, id)
 {
-    const Environment sysEnv = Environment::systemEnvironment();
-    const QString exec = sysEnv.searchInPath("python").toString();
-
     auto interpreterAspect = addAspect<InterpreterAspect>();
     interpreterAspect->setSettingsKey("PythonEditor.RunConfiguation.Interpreter");
-    interpreterAspect->setLabelText(tr("Interpreter:"));
-    interpreterAspect->setDisplayStyle(BaseStringAspect::PathChooserDisplay);
-    interpreterAspect->setHistoryCompleter("PythonEditor.Interpreter.History");
-    interpreterAspect->setValue(exec.isEmpty() ? "python" : exec);
+
+    connect(PythonSettings::instance(), &PythonSettings::interpretersChanged,
+            interpreterAspect, &InterpreterAspect::updateInterpreters);
+
+    interpreterAspect->updateInterpreters(PythonSettings::interpreters());
+    interpreterAspect->setDefaultInterpreter(PythonSettings::defaultInterpreter());
 
     auto scriptAspect = addAspect<MainScriptAspect>();
     scriptAspect->setSettingsKey("PythonEditor.RunConfiguation.Script");
@@ -282,7 +374,7 @@ PythonRunConfiguration::PythonRunConfiguration(Target *target, Core::Id id)
 
     setOutputFormatter<PythonOutputFormatter>();
     setCommandLineGetter([this, interpreterAspect, argumentsAspect] {
-        CommandLine cmd{interpreterAspect->value(), {mainScript()}};
+        CommandLine cmd{interpreterAspect->currentInterpreter().command, {mainScript()}};
         cmd.addArgs(argumentsAspect->arguments(macroExpander()), CommandLine::Raw);
         return cmd;
     });
@@ -737,6 +829,8 @@ bool PythonPlugin::initialize(const QStringList &arguments, QString *errorMessag
 
     ProjectManager::registerProjectType<PythonProject>(PythonMimeType);
 
+    PythonSettings::init();
+
     return true;
 }
 

src/plugins/python/pythonsettings.cpp

@@ -0,0 +1,487 @@
+/****************************************************************************
+**
+** Copyright (C) 2019 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of Qt Creator.
+**
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 as published by the Free Software
+** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+****************************************************************************/
+
+#include "pythonsettings.h"
+
+#include "pythonconstants.h"
+
+#include <coreplugin/dialogs/ioptionspage.h>
+#include "coreplugin/icore.h"
+
+#include <utils/algorithm.h>
+#include <utils/qtcassert.h>
+#include <utils/detailswidget.h>
+#include <utils/environment.h>
+#include <utils/listmodel.h>
+#include <utils/pathchooser.h>
+#include <utils/synchronousprocess.h>
+#include <utils/treemodel.h>
+
+#include <QDir>
+#include <QLabel>
+#include <QPushButton>
+#include <QPointer>
+#include <QSettings>
+#include <QStackedWidget>
+#include <QTreeView>
+#include <QVBoxLayout>
+#include <QWidget>
+
+namespace Python {
+namespace Internal {
+
+using namespace Utils;
+
+class InterpreterDetailsWidget : public QWidget
+{
+public:
+    InterpreterDetailsWidget()
+        : m_name(new QLineEdit)
+        , m_executable(new Utils::PathChooser())
+    {
+        auto mainLayout = new QGridLayout();
+        mainLayout->addWidget(new QLabel(tr("Name:")), 0, 0);
+        mainLayout->addWidget(m_name, 0, 1);
+        mainLayout->addWidget(new QLabel(tr("Executable")), 1, 0);
+        mainLayout->addWidget(m_executable, 1, 1);
+        m_executable->setExpectedKind(Utils::PathChooser::ExistingCommand);
+        setLayout(mainLayout);
+    }
+
+    void updateInterpreter(const Interpreter &interpreter)
+    {
+        m_name->setText(interpreter.name);
+        m_executable->setPath(interpreter.command.toString());
+        m_currentId = interpreter.id;
+    }
+
+    Interpreter toInterpreter()
+    {
+        return {m_currentId, m_name->text(), FilePath::fromUserInput(m_executable->path())};
+    }
+    QLineEdit *m_name = nullptr;
+    PathChooser *m_executable = nullptr;
+    QString m_currentId;
+};
+
+
+class InterpreterOptionsWidget : public QWidget
+{
+public:
+    InterpreterOptionsWidget(const QList<Interpreter> &interpreters,
+                             const QString &defaultInterpreter);
+
+    void apply();
+
+private:
+    QTreeView m_view;
+    ListModel<Interpreter> m_model;
+    InterpreterDetailsWidget *m_detailsWidget = nullptr;
+    QPushButton *m_deleteButton = nullptr;
+    QPushButton *m_makeDefaultButton = nullptr;
+    QString m_defaultId;
+
+    void currentChanged(const QModelIndex &index, const QModelIndex &previous);
+    void addItem();
+    void deleteItem();
+    void makeDefault();
+};
+
+InterpreterOptionsWidget::InterpreterOptionsWidget(const QList<Interpreter> &interpreters, const QString &defaultInterpreter)
+    : m_detailsWidget(new InterpreterDetailsWidget())
+    , m_defaultId(defaultInterpreter)
+{
+    m_model.setDataAccessor([this](const Interpreter &interpreter, int, int role) -> QVariant {
+        if (role == Qt::DisplayRole)
+            return interpreter.name;
+        if (role == Qt::FontRole) {
+            QFont f = font();
+            f.setBold(interpreter.id == m_defaultId);
+            return f;
+        }
+        return {};
+    });
+
+    for (const Interpreter &interpreter : interpreters)
+        m_model.appendItem(interpreter);
+
+    auto mainLayout = new QVBoxLayout();
+    auto layout = new QHBoxLayout();
+    m_view.setModel(&m_model);
+    m_view.setHeaderHidden(true);
+    m_view.setSelectionMode(QAbstractItemView::SingleSelection);
+    m_view.setSelectionBehavior(QAbstractItemView::SelectItems);
+    connect(m_view.selectionModel(),
+            &QItemSelectionModel::currentChanged,
+            this,
+            &InterpreterOptionsWidget::currentChanged);
+    auto buttonLayout = new QVBoxLayout();
+    auto addButton = new QPushButton(InterpreterOptionsWidget::tr("&Add"));
+    connect(addButton, &QPushButton::pressed, this, &InterpreterOptionsWidget::addItem);
+    m_deleteButton = new QPushButton(InterpreterOptionsWidget::tr("&Delete"));
+    m_deleteButton->setEnabled(false);
+    connect(m_deleteButton, &QPushButton::pressed, this, &InterpreterOptionsWidget::deleteItem);
+    m_makeDefaultButton = new QPushButton(InterpreterOptionsWidget::tr("&Make Default"));
+    m_makeDefaultButton->setEnabled(false);
+    connect(m_makeDefaultButton, &QPushButton::pressed, this, &InterpreterOptionsWidget::makeDefault);
+    mainLayout->addLayout(layout);
+    mainLayout->addWidget(m_detailsWidget);
+    m_detailsWidget->hide();
+    setLayout(mainLayout);
+    layout->addWidget(&m_view);
+    layout->addLayout(buttonLayout);
+    buttonLayout->addWidget(addButton);
+    buttonLayout->addWidget(m_deleteButton);
+    buttonLayout->addWidget(m_makeDefaultButton);
+    buttonLayout->addStretch(10);
+}
+
+void InterpreterOptionsWidget::apply()
+{
+    const QModelIndex &index = m_view.currentIndex();
+    if (index.isValid()) {
+        m_model.itemAt(index.row())->itemData = m_detailsWidget->toInterpreter();
+        emit m_model.dataChanged(index, index);
+    }
+
+    QList<Interpreter> interpreters;
+    for (const ListItem<Interpreter> *treeItem : m_model)
+        interpreters << treeItem->itemData;
+    PythonSettings::setInterpreter(interpreters, m_defaultId);
+}
+
+void InterpreterOptionsWidget::currentChanged(const QModelIndex &index, const QModelIndex &previous)
+{
+    if (previous.isValid()) {
+        m_model.itemAt(previous.row())->itemData = m_detailsWidget->toInterpreter();
+        emit m_model.dataChanged(previous, previous);
+    }
+    if (index.isValid()) {
+        m_detailsWidget->updateInterpreter(m_model.itemAt(index.row())->itemData);
+        m_detailsWidget->show();
+    } else {
+        m_detailsWidget->hide();
+    }
+    m_deleteButton->setEnabled(index.isValid());
+    m_makeDefaultButton->setEnabled(index.isValid());
+}
+
+void InterpreterOptionsWidget::addItem()
+{
+    const QModelIndex &index = m_model.indexForItem(
+                m_model.appendItem({QUuid::createUuid().toString(), "Python", FilePath()}));
+    QTC_ASSERT(index.isValid(), return);
+    m_view.setCurrentIndex(index);
+}
+
+void InterpreterOptionsWidget::deleteItem()
+{
+    const QModelIndex &index = m_view.currentIndex();
+    if (index.isValid())
+        m_model.destroyItem(m_model.itemAt(index.row()));
+}
+
+class InterpreterOptionsPage : public Core::IOptionsPage
+{
+    Q_OBJECT
+
+public:
+    InterpreterOptionsPage();
+
+    void setInterpreter(const QList<Interpreter> &interpreters) { m_interpreters = interpreters; }
+    QList<Interpreter> interpreters() const { return m_interpreters; }
+    void setDefaultInterpreter(const QString &defaultId)
+    { m_defaultInterpreterId = defaultId; }
+    Interpreter defaultInterpreter() const;
+
+    QWidget *widget() override;
+    void apply() override;
+    void finish() override;
+
+private:
+    QPointer<InterpreterOptionsWidget> m_widget;
+    QList<Interpreter> m_interpreters;
+    QString m_defaultInterpreterId;
+};
+
+InterpreterOptionsPage::InterpreterOptionsPage()
+{
+    setId(Constants::C_PYTHONOPTIONS_PAGE_ID);
+    setDisplayName(tr("Interpreters"));
+    setCategory(Constants::C_PYTHON_SETTINGS_CATEGORY);
+    setDisplayCategory(tr("Python"));
+    setCategoryIcon(Utils::Icon({{":/python/images/settingscategory_python.png",
+                                  Utils::Theme::PanelTextColorDark}}, Utils::Icon::Tint));
+}
+
+Interpreter InterpreterOptionsPage::defaultInterpreter() const
+{
+    if (m_defaultInterpreterId.isEmpty())
+        return {};
+    return Utils::findOrDefault(m_interpreters, [this](const Interpreter &interpreter) {
+        return interpreter.id == m_defaultInterpreterId;
+    });
+}
+
+QWidget *InterpreterOptionsPage::widget()
+{
+    if (!m_widget)
+        m_widget = new InterpreterOptionsWidget(m_interpreters, m_defaultInterpreterId);
+    return m_widget;
+}
+
+void InterpreterOptionsPage::apply()
+{
+    if (m_widget)
+        m_widget->apply();
+}
+
+void InterpreterOptionsPage::finish()
+{
+    delete m_widget;
+    m_widget = nullptr;
+}
+
+static bool alreadyRegistered(const QList<Interpreter> &pythons, const FilePath &pythonExecutable)
+{
+    return Utils::anyOf(pythons, [pythonExecutable](const Interpreter &interpreter) {
+        return interpreter.command.toFileInfo().canonicalFilePath()
+               == pythonExecutable.toFileInfo().canonicalFilePath();
+    });
+}
+
+Interpreter interpreterForPythonExecutable(const FilePath &python,
+                                           const QString &defaultName,
+                                           bool windowedSuffix = false)
+{
+    SynchronousProcess pythonProcess;
+    pythonProcess.setProcessChannelMode(QProcess::MergedChannels);
+    SynchronousProcessResponse response = pythonProcess.runBlocking(
+        CommandLine(python, {"--version"}));
+    QString name;
+    if (response.result == SynchronousProcessResponse::Finished)
+        name = response.stdOut().trimmed();
+    if (name.isEmpty())
+        name = defaultName;
+    if (windowedSuffix)
+        name += " (Windowed)";
+    return Interpreter{QUuid::createUuid().toString(), name, python};
+}
+
+static InterpreterOptionsPage &interpreterOptionsPage()
+{
+    static InterpreterOptionsPage page;
+    return page;
+}
+
+void InterpreterOptionsWidget::makeDefault()
+{
+    const QModelIndex &index = m_view.currentIndex();
+    if (index.isValid()) {
+        QModelIndex defaultIndex;
+        if (auto *defaultItem = m_model.findItemByData(
+                [this](const Interpreter &interpreter) { return interpreter.id == m_defaultId; })) {
+            defaultIndex = m_model.indexForItem(defaultItem);
+        }
+        m_defaultId = m_model.itemAt(index.row())->itemData.id;
+        emit m_model.dataChanged(index, index, {Qt::FontRole});
+        if (defaultIndex.isValid())
+            emit m_model.dataChanged(defaultIndex, defaultIndex, {Qt::FontRole});
+    }
+}
+
+constexpr char settingsGroupKey[] = "Python";
+constexpr char interpreterKey[] = "Interpeter";
+constexpr char defaultKey[] = "DefaultInterpeter";
+
+struct SavedSettings
+{
+    QList<Interpreter> pythons;
+    QString defaultId;
+};
+
+static SavedSettings fromSettings(QSettings *settings)
+{
+    QList<Interpreter> pythons;
+    settings->beginGroup(settingsGroupKey);
+    const QVariantList interpreters = settings->value(interpreterKey).toList();
+    for (const QVariant &interpreterVar : interpreters) {
+        auto interpreterList = interpreterVar.toList();
+        if (interpreterList.size() != 3)
+            continue;
+        pythons << Interpreter{interpreterList.value(0).toString(),
+                               interpreterList.value(1).toString(),
+                               FilePath::fromVariant(interpreterList.value(2))};
+    }
+
+    const QString defaultId = settings->value(defaultKey).toString();
+
+    settings->endGroup();
+
+    return {pythons, defaultId};
+}
+
+static void toSettings(QSettings *settings, const SavedSettings &savedSettings)
+{
+    settings->beginGroup(settingsGroupKey);
+    const QVariantList interpretersVar
+        = Utils::transform(savedSettings.pythons, [](const Interpreter &interpreter) {
+              return QVariant({interpreter.id, interpreter.name, interpreter.command.toVariant()});
+          });
+    settings->setValue(interpreterKey, interpretersVar);
+    settings->setValue(defaultKey, savedSettings.defaultId);
+    settings->endGroup();
+}
+
+static void addPythonsFromRegistry(QList<Interpreter> &pythons)
+{
+    QSettings pythonRegistry("HKEY_LOCAL_MACHINE\\SOFTWARE\\Python\\PythonCore",
+                             QSettings::NativeFormat);
+    for (const QString &versionGroup : pythonRegistry.childGroups()) {
+        pythonRegistry.beginGroup(versionGroup);
+        QString name = pythonRegistry.value("DisplayName").toString();
+        QVariant regVal = pythonRegistry.value("InstallPath/ExecutablePath");
+        if (regVal.isValid()) {
+            const FilePath &executable = FilePath::fromUserInput(regVal.toString());
+            if (executable.exists() && !alreadyRegistered(pythons, executable)) {
+                pythons << Interpreter{QUuid::createUuid().toString(),
+                                       name,
+                                       FilePath::fromUserInput(regVal.toString())};
+            }
+        }
+        regVal = pythonRegistry.value("InstallPath/WindowedExecutablePath");
+        if (regVal.isValid()) {
+            const FilePath &executable = FilePath::fromUserInput(regVal.toString());
+            if (executable.exists() && !alreadyRegistered(pythons, executable)) {
+                pythons << Interpreter{QUuid::createUuid().toString(),
+                                       name + InterpreterOptionsPage::tr(" (Windowed)"),
+                                       FilePath::fromUserInput(regVal.toString())};
+            }
+        }
+        regVal = pythonRegistry.value("InstallPath/.");
+        if (regVal.isValid()) {
+            const FilePath &path = FilePath::fromUserInput(regVal.toString());
+            const FilePath &python = path.pathAppended(HostOsInfo::withExecutableSuffix("python"));
+            if (python.exists() && !alreadyRegistered(pythons, python))
+                pythons << interpreterForPythonExecutable(python, "Python " + versionGroup);
+            const FilePath &pythonw = path.pathAppended(
+                HostOsInfo::withExecutableSuffix("pythonw"));
+            if (pythonw.exists() && !alreadyRegistered(pythons, pythonw))
+                pythons << interpreterForPythonExecutable(pythonw, "Python " + versionGroup, true);
+        }
+        pythonRegistry.endGroup();
+    }
+}
+
+static void addPythonsFromPath(QList<Interpreter> &pythons)
+{
+    const auto &env = Environment::systemEnvironment();
+
+    if (HostOsInfo::isWindowsHost()) {
+        for (const FilePath &executable : env.findAllInPath("python")) {
+            if (executable.exists() && !alreadyRegistered(pythons, executable))
+                pythons << interpreterForPythonExecutable(executable, "Python from Path");
+        }
+        for (const FilePath &executable : env.findAllInPath("pythonw")) {
+            if (executable.exists() && !alreadyRegistered(pythons, executable))
+                pythons << interpreterForPythonExecutable(executable, "Python from Path", true);
+        }
+    } else {
+        const QStringList filters = {"python",
+                                     "python[1-9].[0-9]",
+                                     "python[1-9].[1-9][0-9]",
+                                     "python[1-9]"};
+        for (const FilePath &path : env.path()) {
+            const QDir dir(path.toString());
+            for (const QFileInfo &fi : dir.entryInfoList(filters)) {
+                const FilePath executable = Utils::FilePath::fromFileInfo(fi);
+                if (executable.exists() && !alreadyRegistered(pythons, executable))
+                    pythons << interpreterForPythonExecutable(executable, "Python from Path");
+            }
+        }
+    }
+}
+
+static QString idForPythonFromPath(QList<Interpreter> pythons)
+{
+    const FilePath &pythonFromPath = Environment::systemEnvironment().searchInPath("python");
+    if (pythonFromPath.isEmpty())
+        return {};
+    const Interpreter &defaultInterpreter
+        = findOrDefault(pythons, [pythonFromPath](const Interpreter &interpreter) {
+              return interpreter.command == pythonFromPath;
+          });
+    return defaultInterpreter.id;
+}
+
+static PythonSettings *settingsInstance = nullptr;
+PythonSettings::PythonSettings() = default;
+
+void PythonSettings::init()
+{
+    QTC_ASSERT(!settingsInstance, return );
+    settingsInstance = new PythonSettings();
+
+    const SavedSettings &settings = fromSettings(Core::ICore::settings());
+    QList<Interpreter> pythons = settings.pythons;
+
+    if (HostOsInfo::isWindowsHost())
+        addPythonsFromRegistry(pythons);
+    addPythonsFromPath(pythons);
+
+    const QString &defaultId = !settings.defaultId.isEmpty() ? settings.defaultId
+                                                             : idForPythonFromPath(pythons);
+    setInterpreter(pythons, defaultId);
+}
+
+void PythonSettings::setInterpreter(const QList<Interpreter> &interpreters, const QString &defaultId)
+{
+    interpreterOptionsPage().setInterpreter(interpreters);
+    interpreterOptionsPage().setDefaultInterpreter(defaultId);
+    toSettings(Core::ICore::settings(), {interpreters, defaultId});
+    if (QTC_GUARD(settingsInstance))
+        emit settingsInstance->interpretersChanged(interpreters, defaultId);
+}
+
+PythonSettings *PythonSettings::instance()
+{
+    QTC_CHECK(settingsInstance);
+    return settingsInstance;
+}
+
+QList<Interpreter> PythonSettings::interpreters()
+{
+    return interpreterOptionsPage().interpreters();
+}
+
+Interpreter PythonSettings::defaultInterpreter()
+{
+    return interpreterOptionsPage().defaultInterpreter();
+}
+
+} // namespace Internal
+} // namespace Python
+
+#include "pythonsettings.moc"

src/plugins/python/pythonsettings.h

@@ -0,0 +1,62 @@
+/****************************************************************************
+**
+** Copyright (C) 2019 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of Qt Creator.
+**
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 as published by the Free Software
+** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+****************************************************************************/
+
+#pragma once
+
+#include <utils/fileutils.h>
+
+#include <QUuid>
+
+namespace Python {
+namespace Internal {
+
+class Interpreter
+{
+public:
+    QString id;
+    QString name;
+    Utils::FilePath command;
+};
+
+class PythonSettings : public QObject
+{
+    Q_OBJECT
+public:
+    static void init();
+
+    static QList<Interpreter> interpreters();
+    static Interpreter defaultInterpreter();
+    static void setInterpreter(const QList<Interpreter> &interpreters, const QString &defaultId);
+    static PythonSettings *instance();
+
+signals:
+    void interpretersChanged(const QList<Interpreter> &interpreters, const QString &defaultId);
+
+private:
+    PythonSettings();
+};
+
+} // namespace Internal
+} // namespace PythonEditor

src/tools/icons/qtcreatoricons.svg

@@ -3217,6 +3217,51 @@
          id="path6672"
          inkscape:connector-curvature="0" />
     </g>
+    <g
+       transform="translate(-213,-84)"
+       id="src/plugins/python/images/settingscategory_python">
+      <use
+         style="display:inline"
+         transform="translate(1128,148)"
+         height="100%"
+         width="100%"
+         id="use2493"
+         xlink:href="#backgroundRect_24"
+         y="0"
+         x="0" />
+      <path
+         sodipodi:nodetypes="ccccccsssscc"
+         inkscape:connector-curvature="0"
+         id="path1631-9"
+         d="m 1112,567 v 1 h 4 v 1 h -4 c -5.3,0 -5.3,7 0,7 v -1.5 c 0,-1.5 1.5,-2.5 2.5,-2.5 h 2 c 1.8137,0 2.5,-0.75 2.5,-2.5 V 567 c 0,-2.66 -7,-2.66 -7,0 z"
+         style="stroke-width:0" />
+      <use
+         x="0"
+         y="0"
+         xlink:href="#path1631-9"
+         id="use2537"
+         transform="rotate(-180,1116,572.5)"
+         width="100%"
+         height="100%" />
+      <path
+         style="fill:#ffffff"
+         d="m 1121,570.75 c 0,1.75 -1.5,3.25 -3.5,3.25 h -2.5 c -0.66,0 -1,0.33 -1,1 v 3 c 0,0 -0.031,1 2.3654,1 1.7918,0 2.6346,0.21875 2.6346,-0.99998 h -4 v -3 h 5 c 4,0 3.5,-4.75 1,-4.75 z"
+         id="path2539"
+         inkscape:connector-curvature="0"
+         sodipodi:nodetypes="sscccscccccs" />
+      <circle
+         style="fill:#ffffff"
+         id="path2541"
+         cx="1113.5"
+         cy="566.5"
+         r="0.625" />
+      <circle
+         style="fill:#000000"
+         id="path2541-4"
+         cx="1117.5"
+         cy="578.5"
+         r="0.5" />
+    </g>
     <g
        id="src/plugins/autotest/images/settingscategory_autotest"
        transform="translate(-220,-84)">