From 06eae8eab4424d5ccb35dcb71cafb4fc99c5a131 Mon Sep 17 00:00:00 2001
From: hegner <benedikt.hegner@cern.ch>
Date: Wed, 13 Sep 2023 15:12:15 +0200
Subject: [PATCH] Introduce a createBuffers macro for the jinja template (#480)

* move Collection::createBuffers template into macro

---------

Co-authored-by: tmadlener <thomas.madlener@desy.de>
---
 python/templates/Collection.cc.jinja2      | 47 +------------------
 python/templates/macros/collections.jinja2 | 53 +++++++++++++++++++++-
 2 files changed, 53 insertions(+), 47 deletions(-)

diff --git a/python/templates/Collection.cc.jinja2 b/python/templates/Collection.cc.jinja2
index 4828750a9..665e2188d 100644
--- a/python/templates/Collection.cc.jinja2
+++ b/python/templates/Collection.cc.jinja2
@@ -173,52 +173,7 @@ podio::SchemaVersionT {{ collection_type }}::getSchemaVersion() const {
   return {{ package_name }}::meta::schemaVersion;
 }
 
-// anonymous namespace for registration with the CollectionBufferFactory. This
-// ensures that we don't have to make up arbitrary namespace names here, since
-// none of this is publicly visible
-namespace {
-podio::CollectionReadBuffers createBuffers(bool isSubset) {
-  auto readBuffers = podio::CollectionReadBuffers{};
-  readBuffers.type = "{{ class.full_type }}Collection";
-  readBuffers.schemaVersion = {{ package_name }}::meta::schemaVersion;
-  readBuffers.data = isSubset ? nullptr : new {{ class.bare_type }}DataContainer;
-
-  // The number of ObjectID vectors is either 1 or the sum of OneToMany and
-  // OneToOne relations
-  const auto nRefs = isSubset ? 1 : {{ OneToManyRelations | length }} + {{ OneToOneRelations | length }};
-  readBuffers.references = new podio::CollRefCollection(nRefs);
-  for (auto& ref : *readBuffers.references) {
-    // Make sure to place usable buffer pointers here
-    ref = std::make_unique<std::vector<podio::ObjectID>>();
-  }
-
-  readBuffers.vectorMembers = new podio::VectorMembersInfo();
-  if (!isSubset) {
-    readBuffers.vectorMembers->reserve({{ VectorMembers | length }});
-{% for member in VectorMembers %}
-    readBuffers.vectorMembers->emplace_back("{{ member.full_type }}", new std::vector<{{ member.full_type }}>);
-{% endfor %}
-  }
-
-  readBuffers.createCollection = [](podio::CollectionReadBuffers buffers, bool isSubsetColl) {
-    {{ collection_type }}Data data(buffers, isSubsetColl);
-    return std::make_unique<{{ collection_type }}>(std::move(data), isSubsetColl);
-  };
-
-  readBuffers.recast = [](podio::CollectionReadBuffers& buffers) {
-    // We only have any of these buffers if this is not a subset collection
-    if (buffers.data) {
-      buffers.data = podio::CollectionWriteBuffers::asVector<{{ class.full_type }}Data>(buffers.data);
-{% if VectorMembers %}
-{% for member in VectorMembers %}
-    (*buffers.vectorMembers)[{{ loop.index0 }}].second = podio::CollectionWriteBuffers::asVector<{{ member.full_type }}>((*buffers.vectorMembers)[{{ loop.index0 }}].second);
-{% endfor %}
-{% endif %}
-    }
-  };
-
-  return readBuffers;
-}
+ {{ macros.createBuffers(class, package_name, collection_type, OneToManyRelations, OneToOneRelations, VectorMembers, 1) }}
 
 // The usual trick with an IIFE and a static variable inside a funtion and then
 // making sure to call that function during shared library loading
diff --git a/python/templates/macros/collections.jinja2 b/python/templates/macros/collections.jinja2
index d07abad19..3224b6fc0 100644
--- a/python/templates/macros/collections.jinja2
+++ b/python/templates/macros/collections.jinja2
@@ -151,4 +151,55 @@ void {{ class.bare_type }}Collection::print(std::ostream& os, bool flush) const
     os.flush();
   }
 }
-{%- endmacro %}
+{% endmacro %}
+
+{% macro createBuffers(class, package_name, collection_type, OneToManyRelations, OneToOneRelations, VectorMembers, schemaVersion) %}
+
+// anonymous namespace for registration with the CollectionBufferFactory. This
+// ensures that we don't have to make up arbitrary namespace names here, since
+// none of this is publicly visible
+namespace {
+podio::CollectionReadBuffers createBuffers(bool isSubset) {
+  auto readBuffers = podio::CollectionReadBuffers{};
+  readBuffers.type = "{{ class.full_type }}Collection";
+  readBuffers.schemaVersion = {{ package_name }}::meta::schemaVersion;
+  readBuffers.data = isSubset ? nullptr : new {{ class.bare_type }}DataContainer;
+
+  // The number of ObjectID vectors is either 1 or the sum of OneToMany and
+  // OneToOne relations
+  const auto nRefs = isSubset ? 1 : {{ OneToManyRelations | length }} + {{ OneToOneRelations | length }};
+  readBuffers.references = new podio::CollRefCollection(nRefs);
+  for (auto& ref : *readBuffers.references) {
+    // Make sure to place usable buffer pointers here
+    ref = std::make_unique<std::vector<podio::ObjectID>>();
+  }
+
+  readBuffers.vectorMembers = new podio::VectorMembersInfo();
+  if (!isSubset) {
+    readBuffers.vectorMembers->reserve({{ VectorMembers | length }});
+{% for member in VectorMembers %}
+    readBuffers.vectorMembers->emplace_back("{{ member.full_type }}", new std::vector<{{ member.full_type }}>);
+{% endfor %}
+  }
+
+  readBuffers.createCollection = [](podio::CollectionReadBuffers buffers, bool isSubsetColl) {
+    {{ collection_type }}Data data(buffers, isSubsetColl);
+    return std::make_unique<{{ collection_type }}>(std::move(data), isSubsetColl);
+  };
+
+  readBuffers.recast = [](podio::CollectionReadBuffers& buffers) {
+    // We only have any of these buffers if this is not a subset collection
+    if (buffers.data) {
+      buffers.data = podio::CollectionWriteBuffers::asVector<{{ class.full_type }}Data>(buffers.data);
+{% if VectorMembers %}
+{% for member in VectorMembers %}
+      (*buffers.vectorMembers)[{{ loop.index0 }}].second = podio::CollectionWriteBuffers::asVector<{{ member.full_type }}>((*buffers.vectorMembers)[{{ loop.index0 }}].second);
+{% endfor %}
+{% endif %}
+    }
+  };
+
+  return readBuffers;
+}
+
+{% endmacro %}