Improve Python detection

src/core/utils/misc.cpp

@@ -226,74 +226,56 @@ QPoint Utils::Misc::screenCenter(QWidget *win)
 #endif
 
 /**
- * Detects the version of python by calling
+ * Detects the python version.
- * "python --version" and parsing the output.
  */
 int Utils::Misc::pythonVersion()
 {
     static int version = -1;
     if (version < 0) {
-        QProcess python_proc;
+        QString versionComplete = pythonVersionComplete().trimmed();
-#if defined(Q_OS_UNIX)
+        QStringList splitted = versionComplete.split('.');
-        /*
+        if (splitted.size() > 1) {
-         * On Unix-Like Systems python2 and python3 should always exist
+            int highVer = splitted.at(0).toInt();
-         * http://legacy.python.org/dev/peps/pep-0394/
+            if ((highVer == 2) || (highVer == 3))
-         */
+                version = highVer;
-        python_proc.start("python3", QStringList() << "--version", QIODevice::ReadOnly);
-        if (python_proc.waitForFinished()) {
-            if (python_proc.exitCode() == 0) {
-                QByteArray output = python_proc.readAllStandardOutput();
-                if (output.isEmpty())
-                    output = python_proc.readAllStandardError();
-                const QByteArray version_str = output.split(' ').last();
-                Logger::instance()->addMessage(QCoreApplication::translate("misc", "Python version: %1").arg(QString(version_str)), Log::INFO);
-                version = 3;
-                return 3;
         }
     }
-        python_proc.start("python2", QStringList() << "--version", QIODevice::ReadOnly);
-        if (python_proc.waitForFinished()) {
-            if (python_proc.exitCode() == 0) {
-                QByteArray output = python_proc.readAllStandardOutput();
-                if (output.isEmpty())
-                    output = python_proc.readAllStandardError();
-                const QByteArray version_str = output.split(' ').last();
-                Logger::instance()->addMessage(QCoreApplication::translate("misc", "Python version: %1").arg(QString(version_str)), Log::INFO);
-                version = 2;
-                return 2;
-            }
-        }
-#else
-        python_proc.start("python", QStringList() << "--version", QIODevice::ReadOnly);
-        if (!python_proc.waitForFinished()) return -1;
-        if (python_proc.exitCode() < 0) return -1;
-        QByteArray output = python_proc.readAllStandardOutput();
-        if (output.isEmpty())
-            output = python_proc.readAllStandardError();
-        const QByteArray version_str = output.split(' ').last();
-        Logger::instance()->addMessage(QCoreApplication::translate("misc", "Python version: %1").arg(QString(version_str)), Log::INFO);
-        if (version_str.startsWith("3."))
-            version = 3;
-        else
-            version = 2;
-#endif
-    }
     return version;
 }
 
+/**
+ * Detects the python executable by calling "python --version".
+ */
 QString Utils::Misc::pythonExecutable()
 {
+    static QString executable;
+    if (executable.isEmpty()) {
+        QProcess pythonProc;
 #if defined(Q_OS_UNIX)
         /*
          * On Unix-Like Systems python2 and python3 should always exist
          * http://legacy.python.org/dev/peps/pep-0394/
          */
-    if (pythonVersion() == 3)
+        pythonProc.start("python3", QStringList() << "--version", QIODevice::ReadOnly);
-        return "python3";
+        if (pythonProc.waitForFinished() && pythonProc.exitCode() == 0) {
-    if (pythonVersion() == 2)
+            executable = "python3";
-        return "python2";
+            return executable;
+        }
+        pythonProc.start("python2", QStringList() << "--version", QIODevice::ReadOnly);
+        if (pythonProc.waitForFinished() && pythonProc.exitCode() == 0) {
+            executable = "python2";
+            return executable;
+        }
 #endif
-    return "python";
+        // Look for "python" in Windows and in UNIX if "python2" and "python3" are
+        // not detected.
+        pythonProc.start("python", QStringList() << "--version", QIODevice::ReadOnly);
+        if (pythonProc.waitForFinished() && pythonProc.exitCode() == 0)
+            executable = "python";
+        else
+            Logger::instance()->addMessage(QCoreApplication::translate("misc", "Python not detected"), Log::INFO);
+    }
+    return executable;
 }
 
 /**
@@ -303,22 +285,20 @@ QString Utils::Misc::pythonExecutable()
  */
 QString Utils::Misc::pythonVersionComplete() {
     static QString version;
-
     if (version.isEmpty()) {
-        if (pythonVersion() < 0)
+        if (pythonExecutable().isEmpty())
-            return QString();
+            return version;
-
+        QProcess pythonProc;
-        QProcess python_proc;
+        pythonProc.start(pythonExecutable(), QStringList() << "--version", QIODevice::ReadOnly);
-        python_proc.start(pythonExecutable(), QStringList() << "--version", QIODevice::ReadOnly);
+        if (pythonProc.waitForFinished() && pythonProc.exitCode() == 0) {
-        if (!python_proc.waitForFinished()) return QString();
+            QByteArray output = pythonProc.readAllStandardOutput();
-        if (python_proc.exitCode() < 0) return QString();
-        QByteArray output = python_proc.readAllStandardOutput();
             if (output.isEmpty())
-            output = python_proc.readAllStandardError();
+                output = pythonProc.readAllStandardError();
-        const QByteArray version_str = output.split(' ').last();
+            const QByteArray versionStr = output.split(' ').last();
-        version = version_str;
+            version = versionStr.trimmed();
+            Logger::instance()->addMessage(QCoreApplication::translate("misc", "Python version: %1").arg(version), Log::INFO);
+        }
     }
-
     return version;
 }
 

src/gui/mainwindow.cpp

@@ -1377,36 +1377,13 @@ void MainWindow::on_actionSearch_engine_triggered()
 
         bool res = false;
 
-        if (pythonVersion == 2) {
+        if ((pythonVersion == 2) || (pythonVersion == 3)) {
-            // Check if python 2.7.x or later
+            // Check python minimum requirement: 2.7.0/3.3.0
-            QString version = Utils::Misc::pythonVersionComplete().trimmed();
+            QString version = Utils::Misc::pythonVersionComplete();
             QStringList splitted = version.split('.');
             if (splitted.size() > 1) {
                 int middleVer = splitted.at(1).toInt();
-                if (middleVer < 7) {
+                if ((pythonVersion == 2 && middleVer < 7) || (pythonVersion == 3 && middleVer < 3)) {
-                    QMessageBox::information(this, tr("Old Python Interpreter"), tr("Your Python version is %1, which is too old. You need at least version 2.7.0 for python2 or 3.3.0 for python3.").arg(version));
-                    actionSearch_engine->setChecked(false);
-                    Preferences::instance()->setSearchEnabled(false);
-                    return;
-                }
-                else {
-                    res = true;
-                }
-            }
-            else {
-                QMessageBox::information(this, tr("Undetermined Python version"), tr("Couldn't decode your Python version: %1").arg(version));
-                actionSearch_engine->setChecked(false);
-                Preferences::instance()->setSearchEnabled(false);
-                return;
-            }
-        }
-        else if (pythonVersion == 3) {
-            // Check if python 3.3.x or later
-            QString version = Utils::Misc::pythonVersionComplete().trimmed();
-            QStringList splitted = version.split('.');
-            if (splitted.size() > 1) {
-                int middleVer = splitted.at(1).toInt();
-                if (middleVer < 3) {
                     QMessageBox::information(this, tr("Old Python Interpreter"), tr("Your Python version %1 is outdated. Please upgrade to latest version for search engines to work. Minimum requirement: 2.7.0/3.3.0.").arg(version));
                     actionSearch_engine->setChecked(false);
                     Preferences::instance()->setSearchEnabled(false);
@@ -1423,9 +1400,6 @@ void MainWindow::on_actionSearch_engine_triggered()
                 return;
             }
         }
-        else {
-            res = false;
-        }
 
         if (res) {
             has_python = true;