Add 'gravelspoon' script that can be used in a meson.build file to ob…

…tain the NumPy include files.

README.md

@@ -43,6 +43,20 @@ setup(name='mypackage',
 )
 ```
 
+### Finding the NumPy include directory
+Mebuex ships with a Python script to discover the system NumPy includes when
+building in the isolated build environment. The `gravelspoon` command that
+helps break out of the build prison can be used in a `meson.build` file as
+follows:
+```python
+incpath_np = run_command(
+  gravelspoon
+)
+
+incdir_np = include_directories([incpath_np])
+```
+
+
 ## Install
 Mebuex can be installed with Pip:
 ```bash
@@ -57,6 +71,11 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 
+### [1.2.0] - 2023-12-29
+#### Added
+- Add the `gravelspoon` command to break out of the setuptools build isolation
+  and find the system NumPy includes.
+
 ### [1.1.7] - 2023-08-20
 #### Added
 - Print error message stderr when re-raising assumed compilation error.

mebuex/scripts/__init__.py

@@ -0,0 +1,8 @@
+# Command line scripts.
+#
+# Author: Malte J. Ziebarth ([email protected])
+#
+# Copyright 2023, Malte J. Ziebarth
+# SPDX-License-Identifier: MIT
+
+from .gravelspoon import numpy_get_include

mebuex/scripts/gravelspoon.py

@@ -0,0 +1,64 @@
+# Breaking out of the setuptools build isolation to use the system's
+# NumPy includes.
+#
+# Author: Malte J. Ziebarth ([email protected])
+#
+# Copyright 2023, Malte J. Ziebarth
+# SPDX-License-Identifier: MIT
+
+
+def numpy_get_include():
+    """
+    This function tries to find the NumPy include directory,
+    potentially within a build isolation, and prints the include
+    path to standard out.
+    """
+    try:
+        # In case things work out of the box:
+        import numpy
+        print(numpy.get_include())
+
+    except ImportError:
+        import subprocess
+        import sys
+        from pathlib import Path
+        from os import rename, symlink
+        np_incl_byte = subprocess.check_output(
+            [sys.executable,'-c','import os;os.chdir("..");import numpy;'
+                                 'print(numpy.get_include())'],
+            env={}
+        )
+
+        np_include = np_incl_byte.decode().strip()
+
+        # Make numpy available in the isolated environment this code is running
+        # in. Do this by symlinking the previously discovered system NumPy
+        # package into a site-package directory found in the isolated
+        # environment Python path.
+        found_site_packages = False
+        success = False
+        for path in sys.path[::-1]:
+            p = Path(path)
+            if 'site-packages' in path:
+                found_site_packages = True
+                p = Path(path)
+                if not p.exists():
+                    continue
+                is_dir = (p / "numpy").is_dir()
+                if is_dir:
+                    rename((p / "numpy").resolve(), (p / "numpyold").resolve())
+                symlink(Path(np_include).parent.parent.resolve(),
+                        (p / "numpy").resolve())
+                success = True
+                break
+
+        if not success:
+            msg = "Could not link the NumPy package to the isolated " \
+                  "site-packages."
+            if found_site_packages:
+                msg += " Found site-packages but did not exist."
+            else:
+                msg += " Found no site-pacakges."
+            raise RuntimeError(msg)
+
+        print(np_include)

pyproject.toml

@@ -3,7 +3,7 @@ requires = ["setuptools>=61"]
 
 [project]
 name = "mebuex"
-version = "1.1.7"
+version = "1.2.0"
 authors = [
     {name = "Malte J. Ziebarth", email = "[email protected]"},
 ]
@@ -28,5 +28,8 @@ license = {text="MIT"}
 "Homepage" = "https://github.com/mjziebarth/Mebuex"
 "Bug Tracker" = "https://github.com/mjziebarth/Mebuex/issues"
 
+[project.scripts]
+gravelspoon = "mebuex.scripts:numpy_get_include"
+
 [tool.setuptools]
-packages = ["mebuex"]
+packages = ["mebuex","mebuex.scripts"]