Allow dependent packages to register include paths with xobjects

xobjects/context.py

@@ -6,9 +6,9 @@
 import logging
 import os
 import weakref
-import xobjects as xo
 from abc import ABC, abstractmethod
 from collections import defaultdict
+from importlib.metadata import entry_points
 from pathlib import Path
 from typing import (
     Dict,
@@ -354,6 +354,26 @@ def build_kernels(
     ) -> Dict[Tuple[str, tuple], KernelType]:
         pass
 
+    def get_installed_c_source_paths(self) -> List[str]:
+        """Returns a list of include paths registered in dependent packages.
+
+        In a package that depends on xobjects, you can register C source paths
+        using the entry point `xobjects.c_sources`. A path to the directory
+        containing the specified module will be added to the include path when
+        building kernels. For example, the following will allow to write
+        ``#include <xtrack/path/to/some/header.h>`` in kernel sources:
+
+         .. code-block:: toml
+            [project.entry-points.xobjects]
+            include = "xtrack"
+        """
+        sources = []
+        for ep in entry_points(group='xobjects', name='include'):
+            module = ep.load()
+            path = Path(module.__file__).parents[1]
+            sources.append(str(path))
+        return sources
+
     @abstractmethod
     def nparray_to_context_array(self, arr):
         return arr

xobjects/context_cpu.py

@@ -426,6 +426,11 @@ def compile_kernel(
             xtr_compile_args.append("-DXO_CONTEXT_CPU_SERIAL")
             xtr_link_args.append("-DXO_CONTEXT_CPU_SERIAL")
 
+        extra_include_paths = self.get_installed_c_source_paths()
+        include_flags = [f'-I{path}' for path in extra_include_paths]
+        xtr_compile_args.extend(include_flags)
+        xtr_link_args.extend(include_flags)
+
         if os.name == "nt":  # windows
             # TODO: to be handled properly
             xtr_compile_args = []

xobjects/context_cupy.py

@@ -456,6 +456,10 @@ def build_kernels(
                 fid.write(specialized_source)
 
         extra_compile_args = (*extra_compile_args, "-DXO_CONTEXT_CUDA")
+        extra_include_paths = self.get_installed_c_source_paths()
+        include_flags = [f'-I{path}' for path in extra_include_paths]
+        xtr_compile_args.extend(include_flags)
+
         module = cupy.RawModule(
             code=specialized_source, options=extra_compile_args
         )

xobjects/context_pyopencl.py

@@ -219,8 +219,12 @@ def build_kernels(
             with open(save_source_as, "w") as fid:
                 fid.write(specialized_source)
 
+        extra_include_paths = self.get_installed_c_source_paths()
+        include_flags = [f'-I{path}' for path in extra_include_paths]
+
         extra_compile_args = (
             *extra_compile_args,
+            *include_flags,
             "-cl-std=CL2.0",
             "-DXO_CONTEXT_CL",
         )