Short value by default in TOML

Author: franzpoeschel

docs/source/backends/json.rst

@@ -67,7 +67,7 @@ Attributes
 In order to avoid name clashes, attributes are generally stored within a separate subgroup ``attributes``.
 
 Attributes can be stored in two formats.
-The format is selected by the :ref:`JSON/TOML parameter<backendconfig>` ``json.attribute.mode`` (resp. ``toml.attribute.mode``) with possible values ``["long", "short"]`` (default: ``"long"`` in openPMD 1.*, ``"short"`` in openPMD >= 2.0).
+The format is selected by the :ref:`JSON/TOML parameter<backendconfig>` ``json.attribute.mode`` (resp. ``toml.attribute.mode``) with possible values ``["long", "short"]`` (default: ``"long"`` for JSON in openPMD 1.*, ``"short"`` otherwise, i.e. generally in openPMD 2.*, but always in TOML).
 
 Attributes in **long format** store the datatype explicitly, by representing attributes as JSON objects.
 Every such attribute is itself a JSON object with two keys:

src/IO/JSON/JSONIOHandlerImpl.cpp

@@ -457,9 +457,18 @@ void JSONIOHandlerImpl::createFile(
 
     if (m_attributeModeSpecificationVia == SpecificationVia::DefaultValue)
     {
-        m_attributeMode = parameters.openPMDversion >= "2."
-            ? AttributeMode::Short
-            : AttributeMode::Long;
+        switch (m_fileFormat)
+        {
+
+        case FileFormat::Json:
+            m_attributeMode = parameters.openPMDversion >= "2."
+                ? AttributeMode::Short
+                : AttributeMode::Long;
+            break;
+        case FileFormat::Toml:
+            m_attributeMode = AttributeMode::Short;
+            break;
+        }
     }
 
     if (!writable->written)