Add documentation

include/nlohmann/detail/json_custom_base_class.hpp

@@ -7,6 +7,23 @@ namespace nlohmann
 namespace detail
 {
 
+/*!
+@brief Default base class of the @ref basic_json class.
+
+So that the correct implementation of the copy / move ctors / assign operators
+of @ref basic_json does not require complex case distinctions
+(no base class / custom base class), @ref basic_json always a base class.
+By default this class is used, since empty and thus has no effect on the
+behaviour of @ref basic_json.
+
+
+So that the correct implementation of the copy / move ctors / assign operators
+of @ref basic_json does not require complex case distinctions
+(no base class / custom base class used as customization point),
+@ref basic_json always has a base class.
+By default, this class is used because it is empty and thus has no effect
+on the behavior of @ref basic_json.
+*/
 struct json_default_base {};
 
 template<class T>

tests/src/unit-custom-base-class.cpp

@@ -35,6 +35,8 @@ SOFTWARE.
 
 #include <nlohmann/json.hpp>
 
+// Test extending nlohmann::json by using a custom base class.
+// Add some metadata to each node ant test the behaviour of copy / move
 template<class MetaDataType>
 class json_metadata
 {
@@ -201,6 +203,8 @@ TEST_CASE("JSON Node Metadata")
     }
 }
 
+// Test extending nlohmann::json by using a custom base class.
+// Add a custom member function template iterating over the whole json tree.
 class visitor_adaptor
 {
   public: