Migrate from pybind11 to nanobind

rclpy/CMakeLists.txt

@@ -38,10 +38,16 @@ find_package(rosidl_runtime_c REQUIRED)
 cmake_policy(SET CMP0094 NEW)
 set(Python3_FIND_UNVERSIONED_NAMES FIRST)
 
-# Find python before pybind11
+# Find python before nanobind
 find_package(Python3 REQUIRED COMPONENTS Interpreter Development)
 
-find_package(pybind11 REQUIRED)
+# nanobind's CMake config requires the new-style FindPython module with the
+# Python::Module target defined. Reuse the interpreter found above so both
+# find_package calls agree on the same Python installation.
+set(Python_EXECUTABLE "${Python3_EXECUTABLE}")
+find_package(Python REQUIRED COMPONENTS Interpreter Development.Module)
+
+find_package(nanobind REQUIRED)
 
 # enables using the Python extensions from the build space for testing
 file(WRITE "${CMAKE_CURRENT_BINARY_DIR}/test_rclpy/__init__.py" "")
@@ -69,10 +75,10 @@ function(configure_build_install_location _library_name)
   )
 endfunction()
 
-# Split from main extension and converted to pybind11
-pybind11_add_module(_rclpy_pybind11
+# Split from main extension and converted to nanobind
+nanobind_add_module(_rclpy_nanobind
   src/rclpy/_rclpy_logging.cpp
-  src/rclpy/_rclpy_pybind11.cpp
+  src/rclpy/_rclpy_nanobind.cpp
   src/rclpy/action_client.cpp
   src/rclpy/action_goal_handle.cpp
   src/rclpy/action_server.cpp
@@ -111,13 +117,13 @@ pybind11_add_module(_rclpy_pybind11
 )
 
 if(CMAKE_C_COMPILER_ID MATCHES "Clang" AND NOT APPLE)
-  target_link_libraries(_rclpy_pybind11 PRIVATE atomic)
+  target_link_libraries(_rclpy_nanobind PRIVATE atomic)
 endif()
 
-target_include_directories(_rclpy_pybind11 PRIVATE
+target_include_directories(_rclpy_nanobind PRIVATE
   src/rclpy/
 )
-target_link_libraries(_rclpy_pybind11 PRIVATE
+target_link_libraries(_rclpy_nanobind PRIVATE
   ament_cmake_ros_core::ament_ros_cxx_standard
   lifecycle_msgs::lifecycle_msgs__rosidl_generator_c
   lifecycle_msgs::lifecycle_msgs__rosidl_typesupport_c
@@ -130,7 +136,23 @@ target_link_libraries(_rclpy_pybind11 PRIVATE
   rcutils::rcutils
   rosidl_runtime_c::rosidl_runtime_c
 )
-configure_build_install_location(_rclpy_pybind11)
+configure_build_install_location(_rclpy_nanobind)
+
+# Generate the type stubs for the extension module into the source tree,
+# so that they stay committed alongside the bindings.
+nanobind_add_stub(_rclpy_nanobind_stub
+  MODULE _rclpy_nanobind
+  OUTPUT "${CMAKE_CURRENT_SOURCE_DIR}/rclpy/impl/_rclpy_nanobind.pyi"
+  PYTHON_PATH "${CMAKE_CURRENT_BINARY_DIR}/test_rclpy"
+  PATTERN_FILE "${CMAKE_CURRENT_SOURCE_DIR}/stubgen_pattern.pat"
+  DEPENDS _rclpy_nanobind "${CMAKE_CURRENT_SOURCE_DIR}/stubgen_pattern.pat"
+)
+nanobind_add_stub(_rclpy_nanobind_service_introspection_stub
+  MODULE _rclpy_nanobind.service_introspection
+  OUTPUT "${CMAKE_CURRENT_SOURCE_DIR}/rclpy/impl/service_introspection.pyi"
+  PYTHON_PATH "${CMAKE_CURRENT_BINARY_DIR}/test_rclpy"
+  DEPENDS _rclpy_nanobind
+)
 
 if(NOT WIN32)
   ament_environment_hooks(
@@ -175,7 +197,7 @@ if(BUILD_TESTING)
   target_include_directories(test_python_allocator PRIVATE src/rclpy)
   target_link_libraries(test_python_allocator
     ament_cmake_ros_core::ament_ros_cxx_standard
-    pybind11::embed)
+    Python3::Python)
 
   if(NOT _typesupport_impls STREQUAL "")
     # Run each test in its own pytest invocation to isolate any global state in rclpy

rclpy/package.xml

@@ -25,7 +25,7 @@
   <build_depend>rcl_lifecycle</build_depend>
   <build_depend>rcl_logging_interface</build_depend>
   <build_depend>rcl_yaml_param_parser</build_depend>
-  <build_depend>pybind11-dev</build_depend>
+  <build_depend>nanobind-dev</build_depend>
   <build_depend>python3-dev</build_depend>
   <build_depend>rcpputils</build_depend>
   <build_depend>rcutils</build_depend>

rclpy/rclpy/duration.py

@@ -32,7 +32,7 @@ def __init__(self, *, seconds: Union[int, float] = 0, nanoseconds: Union[int, fl
         total_nanoseconds = int(seconds * S_TO_NS)
         total_nanoseconds += int(nanoseconds)
         if total_nanoseconds >= 2**63 or total_nanoseconds < -2**63:
-            # pybind11 would raise TypeError, but we want OverflowError
+            # nanobind would raise TypeError, but we want OverflowError
             raise OverflowError(
                 'Total nanoseconds value is too large to store in C duration.')
         self._duration_handle = _rclpy.rcl_duration_t(total_nanoseconds)

rclpy/rclpy/experimental/events_executor.py

@@ -29,15 +29,6 @@ def EventsExecutor(*, context: typing.Optional[rclpy.Context] = None) -> rclpy.e
     # Python backtrace dumped with the crash.
     faulthandler.enable()
 
-    ex = typing.cast(rclpy.executors.Executor, _rclpy.EventsExecutor(context))
-
-    # rclpy.Executor does this too.  Note, the context itself is smart enough to check
-    # for bound methods, and check whether the instances they're bound to still exist at
-    # callback time, so we don't have to worry about tearing down this stale callback at
-    # destruction time.
-    # TODO(bmartin427) This should really be done inside of the EventsExecutor
-    # implementation itself, but I'm unable to figure out a pybind11 incantation that
-    # allows me to pass this bound method call from C++.
-    context.on_shutdown(ex.wake)
-
-    return ex
+    # Note the EventsExecutor implementation takes care of registering a wake-on-shutdown
+    # callback with the context.
+    return typing.cast(rclpy.executors.Executor, _rclpy.EventsExecutor(context))