BehaviorTree.PY

Minimal python binding to https://github.com/BehaviorTree/BehaviorTree.CPP

Usage

By default, the library registers the built-in types. To register custom types, you need to create a shared library with the type converters and load it in python.

add_library(bt_custom_types SHARED src/custom_types.cpp)
target_compile_features(bt_custom_types PRIVATE cxx_std_20)
target_compile_definitions(bt_custom_types PRIVATE BT_PLUGIN_EXPORT)
target_link_libraries(
  bt_custom_types PRIVATE behaviortree_py::behaviortree_py_lib
                          py_binding_tools::py_binding_tools)
install(
  TARGETS bt_custom_types
  LIBRARY DESTINATION share/${PROJECT_NAME}/bt_type_converters
  ARCHIVE DESTINATION share/${PROJECT_NAME}/bt_type_converters
  RUNTIME DESTINATION share/${PROJECT_NAME}/bt_type_converters)

#include <behaviortree_py/behaviortree_py.hpp>
#include <geometry_msgs/msg/pose_stamped.hpp>
// For the typecasters
#include <py_binding_tools/ros_msg_typecasters.h>

BT_REGISTER_TYPE_CONVERTER(geometry_msgs::msg::PoseStamped,
                           geometry_msgs::msg::Pose);

import behaviortree_py as bt
...
bt.load_type_converters(
    get_package_share_directory("my_package")
    + "/bt_type_converters/libbt_custom_types.so"
)
...

Stubs generation

If you want the stubs to be generated, you need to install the package mypy:

sudo apt install mypy

Limitations

• Only register_simple_action, register_simple_condition, and register_simple_decorator are currently supported.
• Due to limitations of BT::Any, only copy-constructible types are supported.
• Due to how pybind11 handle memory, mixing std::shared_ptr and std::unique_ptr between Python/C++ is not supported (You can't have an (in/out)_port with a shared_ptr/unique_ptr if you are planning to share it between Python/C++).

Acknowledgements

• convertFromString is based on BehaviorTree/BehaviorTree.CPP#634
• The TypeConverter is based on moveit_task_constructor's pybind11 implementation.