container: plugins: root: rewrite example plugin

- Reorganizes to utilize new pluggable framework
- Refactors, adds/updates documentation

container/plugins/root/example/internal/example.hh

@@ -0,0 +1,68 @@
+// docker-finance | modern accounting for the power-user
+//
+// Copyright (C) 2024-2025 Aaron Fiore (Founder, Evergreen Crypto LLC)
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation  either version 3 of the License  or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not  see <https://www.gnu.org/licenses/>.
+
+//! \file
+//! \author Aaron Fiore (Founder, Evergreen Crypto LLC)
+//! \note File intended to be loaded into ROOT.cern framework / Cling interpreter
+//! \since docker-finance 1.1.0
+
+#ifndef CONTAINER_PLUGINS_ROOT_EXAMPLE_INTERNAL_EXAMPLE_HH_
+#define CONTAINER_PLUGINS_ROOT_EXAMPLE_INTERNAL_EXAMPLE_HH_
+
+#include <string>
+
+// NOTE: `dfi` API headers are included by default
+
+namespace dfi::plugin::example
+{
+//! \brief An example plugin implementation class
+//!
+//! \warning When implementing pluggables, prefer member functions with
+//!   definitions within source file(s) over certain lambdas to prevent
+//!   root segfaults. TODO(afiore): investigate.
+//!
+//! \note For demonstration purposes only
+//!
+//! \ingroup cpp_plugin_impl
+//! \since docker-finance 1.1.0
+class Example
+{
+ public:
+  //! \brief Example plugin function 1
+  //! \details Directly access docker-finance crypto abstractions and
+  //!   print a handful of SHA2-256 libsodium-generated hashes of
+  //!   Crypto++-generated cryptographically secure random numbers
+  void example1();
+
+  //! \brief Example plugin function 2
+  //! \details Directly access underlying docker-finance shell environment
+  void example2();
+
+  //! \brief Example plugin function 3
+  //! \details Execute docker-finance shell commands
+  void example3();
+
+ protected:
+  std::string make_cmd(const std::string& base, const std::string& arg);
+  void exec_cmd(const std::string& cmd);
+  void print_env(const std::string& env);
+};
+}  // namespace dfi::plugin::example
+
+#endif  // CONTAINER_PLUGINS_ROOT_EXAMPLE_INTERNAL_EXAMPLE_HH_
+
+// # vim: sw=2 sts=2 si ai et