doT C++ Code file template for the VSCode extension File Template Manager

CPP Code.cpp

{{
  let date = new Date($.DATE);
  let date_string = date.getDate().toString().padStart(2, '0') + '.' + (date.getMonth() + 1).toString().padStart(2, '0') + '.' + date.getFullYear();
  let paths = $.DIR.split('/');
  let index = paths.lastIndexOf('src');
  let has_ns = index > 0 && index < paths.length;
  let ns = "";
  if (has_ns) {
    ns = paths[index - 1];
  }
  let header_dir = ns;
  if (index + 1 < paths.length) {
    header_dir += '/' + paths.slice(index + 1).join('/');
  }
}}
//
// Created by {{= $.AUTHOR }} on {{= date_string }}.
//

#include "{{=header_dir}}/{{=$.NAME}}.h"

{{? has_ns }}
namespace {{=ns}}
{
  
}  // namespace {{=ns}}
{{?}}

This template may be too specific for your use case but it could be a good starting point.
It assumes a folder structure of
[...]/${PROJECT}/src/.../code_file.cpp
where ${PROJECT} is also the namespace.

Required variables
It requires a variable named AUTHOR to be set in File Templates Manager's settings.
To do so, open the VS Code settings search for "Custom Vars" and edit in the settings.json.
In the settings.json add the following line "templates.customVars": { "AUTHOR": "Your Name" }

Full example:
Creating a code file named some_project/src/some_example_class.cpp will create:

//
// Created by Your Name on 26.04.2019.
//

#include "some_project/some_example_class.h"

namespace some_project
{

} // some_project

You can change the format of the date by changing the date_string variable in the third line.