Add NoOutput class to disable output writing.

corsika/detail/output/NoOutput.inl

+/*
+ * (c) Copyright 2021 CORSIKA Project, corsika-project@lists.kit.edu
+ *
+ * This software is distributed under the terms of the GNU General Public
+ * Licence version 3 (GPL Version 3). See file LICENSE for a full version of
+ * the license.
+ */
+#pragma once
+
+namespace corsika {
+
+  NoOutput::NoOutput()
+      : {}
+
+  void NoOutput::startOfRun(std::filesystem::path const& directory) {}
+
+  void NoOutput::startOfEvent() {}
+
+  void NoOutput::endOfEvent() {}
+
+  void NoOutput::endOfRun() {}
+
+  YAML::Node NoOutput::getConfig() const { return YAML::Node(); }
+
+  YAML::Node NoOutput::getFinalOutput() const { return YAML::Node(); }
+
+  template <typename... TVArgs>
+  void NoOutput::write(TVArgs&& args...) {}
+
+} // namespace corsika

corsika/output/NoOutput.hpp

+/*
+ * (c) Copyright 2021 CORSIKA Project, corsika-project@lists.kit.edu
+ *
+ * This software is distributed under the terms of the GNU General Public
+ * Licence version 3 (GPL Version 3). See file LICENSE for a full version of
+ * the license.
+ */
+#pragma once
+
+#include <corsika/output/BaseOutput.hpp>
+
+namespace corsika {
+
+  /**
+   * This class can be used as a drop-in for any output template
+   * and doesn't write *any* output files.
+   *
+   */
+  class NoOutput : public BaseOutput {
+
+  public:
+    /**
+     * Construct a blank output.
+     */
+    NoOutput();
+
+    /**
+     * Called at the start of each run.
+     */
+    virtual void startOfRun(std::filesystem::path const& directory) final override;
+
+    /**
+     * Called at the start of each event/shower.
+     */
+    virtual void startOfEvent() final override;
+
+    /**
+     * Called at the end of each event/shower.
+     */
+    virtual void endOfEvent() final override;
+
+    /**
+     * Called at the end of each run.
+     */
+    virtual void endOfRun() final override;
+
+    /**
+     * Get the configuration of this output.
+     */
+    virtual YAML::Node getConfig() const final override;
+
+    /**
+     * Accept any arguments and ignore them.
+     */
+    template <typename... TVArgs>
+    void write(TVArgs&& args...);
+
+    /**
+     * Get final text outputs for the config file.
+     */
+    virtual YAML::Node getFinalOutput() const final override;
+  };
+
+} // namespace corsika
+
+#include <corsika/detail/output/NoOutput.inl>