From 1e9cfe84e004db881aa9346790f2133bcd14cd93 Mon Sep 17 00:00:00 2001
From: Mateusz Jakub Fila <mateusz.jakub.fila@cern.ch>
Date: Fri, 16 Aug 2024 09:24:50 +0200
Subject: [PATCH] make methods const when appropriate

---
 k4FWCore/components/MetadataSvc.cpp      |  3 ++-
 k4FWCore/components/MetadataSvc.h        |  5 +++--
 k4FWCore/components/Writer.cpp           |  3 ++-
 k4FWCore/include/k4FWCore/IMetadataSvc.h | 11 +++++++----
 4 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/k4FWCore/components/MetadataSvc.cpp b/k4FWCore/components/MetadataSvc.cpp
index 25adeaf8..d87f0845 100644
--- a/k4FWCore/components/MetadataSvc.cpp
+++ b/k4FWCore/components/MetadataSvc.cpp
@@ -43,7 +43,8 @@ StatusCode MetadataSvc::initialize() {
 
 StatusCode MetadataSvc::finalize() { return Service::finalize(); }
 
-podio::Frame* MetadataSvc::getFrame() { return m_frame.get(); }
+const podio::Frame* MetadataSvc::getFrame() const { return m_frame.get(); }
+podio::Frame*       MetadataSvc::getFrame() { return m_frame.get(); }
 void MetadataSvc::setFrame(podio::Frame&& frame) { m_frame = std::make_unique<podio::Frame>(std::move(frame)); }
 
 DECLARE_COMPONENT(MetadataSvc)
diff --git a/k4FWCore/components/MetadataSvc.h b/k4FWCore/components/MetadataSvc.h
index 4023124a..b7273ebd 100644
--- a/k4FWCore/components/MetadataSvc.h
+++ b/k4FWCore/components/MetadataSvc.h
@@ -42,8 +42,9 @@ class MetadataSvc : public extends<Service, IMetadataSvc> {
 
   std::unique_ptr<podio::Frame> m_frame;
 
-  podio::Frame* getFrame() override;
-  void          setFrame(podio::Frame&& frame) override;
+  const podio::Frame* getFrame() const override;
+  podio::Frame*       getFrame() override;
+  void                setFrame(podio::Frame&& frame) override;
 };
 
 #endif
diff --git a/k4FWCore/components/Writer.cpp b/k4FWCore/components/Writer.cpp
index 94952bcf..f44dce11 100644
--- a/k4FWCore/components/Writer.cpp
+++ b/k4FWCore/components/Writer.cpp
@@ -34,6 +34,7 @@
 
 #include <GaudiKernel/IHiveWhiteBoard.h>
 #include <memory>
+#include <utility>
 
 class Writer final : public Gaudi::Functional::Consumer<void(const EventContext&)> {
 public:
@@ -121,7 +122,7 @@ class Writer final : public Gaudi::Functional::Consumer<void(const EventContext&
     }
     iosvc->getWriter()->writeFrame(config_metadata_frame, "configuration_metadata");
 
-    if (auto* metadata_frame = m_metadataSvc->getFrame(); metadata_frame) {
+    if (const auto* metadata_frame = std::as_const(*m_metadataSvc).getFrame(); metadata_frame) {
       iosvc->getWriter()->writeFrame(*metadata_frame, podio::Category::Metadata);
     }
 
diff --git a/k4FWCore/include/k4FWCore/IMetadataSvc.h b/k4FWCore/include/k4FWCore/IMetadataSvc.h
index 8ad64727..c88df593 100644
--- a/k4FWCore/include/k4FWCore/IMetadataSvc.h
+++ b/k4FWCore/include/k4FWCore/IMetadataSvc.h
@@ -27,8 +27,8 @@ class IMetadataSvc : virtual public IInterface {
 public:
   DeclareInterfaceID(IMetadataSvc, 1, 0);
 
-  virtual podio::Frame* getFrame()                     = 0;
-  virtual void          setFrame(podio::Frame&& frame) = 0;
+  virtual const podio::Frame* getFrame() const               = 0;
+  virtual void                setFrame(podio::Frame&& frame) = 0;
 
   template <typename T> void put(const std::string& name, const T& obj) {
     if (!getFrame()) {
@@ -37,13 +37,16 @@ class IMetadataSvc : virtual public IInterface {
     getFrame()->putParameter(name, obj);
   }
 
-  template <typename T> std::optional<T> get(const std::string& name) {
-    auto* frame = getFrame();
+  template <typename T> std::optional<T> get(const std::string& name) const {
+    const auto* frame = getFrame();
     if (!frame) {
       return std::nullopt;
     }
     return frame->getParameter<T>(name);
   }
+
+protected:
+  virtual podio::Frame* getFrame() = 0;
 };
 
 #endif