using json_base_class_t = detail::json_base_class<CustomBaseClass>;

The base class used to inject custom functionality into each instance of basic_json. Examples of such functionality might be metadata, additional member functions (e.g., visitors), or other application-specific code.

CustomBaseClass : the base class to be added to basic_json

The default value for CustomBaseClass is void. In this case an empty base class is used and no additional functionality is injected.

The type CustomBaseClass has to be a default-constructible class. basic_json only supports copy/move construction/assignment if CustomBaseClass does so as well.

??? example

The following code shows how to inject custom data and methods for each node.
 
```cpp
--8<-- "examples/json_base_class_t.cpp"
```

Output:

```json
--8<-- "examples/json_base_class_t.output"
```

• Added in version 3.12.0.