Python: Allow source dists to install correctly

This uses PEP 517 which causes pybind11 to be installed in a temporary location at build time.

https://martin-thoma.com/pyproject-toml/

Unfortunately when pybind11 is installed there, it produces the wrong include path, so this inclludes a workaround. Hopefully when that issue is fixed the workaround can be removed:

pybind/pybind11#1067

I’ve also posted the workaround here:

pybind/python_example#45

Author: paulmelnikow

.gitignore

@@ -1,2 +1,6 @@
 #Common folder for building objects
 build/
+/python/dist/
+/python/*.egg-info
+/python/.eggs
+/python/tiny_obj_loader.h

python/MANIFEST.in

@@ -0,0 +1,6 @@
+# Copy the header file into the python/ folder.
+include ../tiny_obj_loader.h
+# Include it in the source distribution.
+include tiny_obj_loader.h
+
+include pyproject.toml

python/bindings.cc

@@ -1,6 +1,6 @@
-#include "pybind11/pybind11.h"
-#include "pybind11/stl.h"
-#include "pybind11/numpy.h"
+#include <pybind11/pybind11.h>
+#include <pybind11/stl.h>
+#include <pybind11/numpy.h>
 #include <cstring>
 
 // Use double precision for better python integration.

python/pyproject.toml

@@ -0,0 +1,2 @@
+[build-system]
+requires = ["setuptools", "wheel", "pybind11>=2.3"]

python/setup.py

@@ -1,28 +1,80 @@
 import setuptools
 
 with open("README.md", "r") as fh:
-    long_description= fh.read()
+    long_description = fh.read()
+
+# Adapted from https://github.com/pybind/python_example/blob/master/setup.py
+class get_pybind_include(object):
+    """Helper class to determine the pybind11 include path
+    The purpose of this class is to postpone importing pybind11
+    until it is actually installed, so that the ``get_include()``
+    method can be invoked. """
+
+    def __init__(self, user=False, pep517=False):
+        self.user = user
+        self.pep517 = pep517
+
+    def __str__(self):
+        import os
+        import pybind11
+
+        interpreter_include_path = pybind11.get_include(self.user)
+
+        if self.pep517:
+            # When pybind11 is installed permanently in site packages, the headers
+            # will be in the interpreter include path above. PEP 517 provides an
+            # experimental feature for build system dependencies. When installing
+            # a package from a source distribvution, first its build dependencies
+            # are installed in a temporary location. pybind11 does not return the
+            # correct path for this condition, so we glom together a second path,
+            # and ultimately specify them _both_ in the include search path.
+            # https://github.com/pybind/pybind11/issues/1067
+            return os.path.abspath(
+                os.path.join(
+                    os.path.dirname(pybind11.__file__),
+                    "..",
+                    "..",
+                    "..",
+                    "..",
+                    "include",
+                    os.path.basename(interpreter_include_path),
+                )
+            )
+        else:
+            return interpreter_include_path
+
 
 # `tiny_obj_loader.cc` contains implementation of tiny_obj_loader.
-m = setuptools.Extension('tinyobjloader',
-              sources = ['bindings.cc', 'tiny_obj_loader.cc'],
-              extra_compile_args=['-std=c++11'],
-              include_dirs = ['../', '../pybind11/include']
-              )
-
-
-setuptools.setup (name = 'tinyobjloader',
-       version = '0.1',
-       description = 'Python module for tinyobjloader',
-       long_description = long_description,
-       long_description_content_type = "text/markdown",
-       author="Syoyo Fujita",
-       author_email="[email protected]",
-       url="https://github.com/syoyo/tinyobjloader",
-       classifiers=[
-           "License :: OSI Approved :: MIT License",
-       ],
-       packages=setuptools.find_packages(),
-       ext_modules = [m])
+m = setuptools.Extension(
+    "tinyobjloader",
+    extra_compile_args=["-std=c++11"],
+    sources=["bindings.cc", "tiny_obj_loader.cc"],
+    include_dirs=[
+        # Support `build_ext` finding tinyobjloader (without first running
+        # `sdist`).
+        "..",
+        # Support `build_ext` finding pybind 11 (provided it's permanently
+        # installed).
+        get_pybind_include(),
+        get_pybind_include(user=True),
+        # Support building from a source distribution finding pybind11 from
+        # a PEP 517 temporary install.
+        get_pybind_include(pep517=True),
+    ],
+    language="c++",
+)
 
 
+setuptools.setup(
+    name="tinymetabobjloader",
+    version="0.1.0",
+    description="Experimental fork of tinyobjloader Python module",
+    long_description=long_description,
+    long_description_content_type="text/markdown",
+    author="Syoyo Fujita, Paul Melnikow",
+    author_email="[email protected], [email protected]",
+    url="https://github.com/metabolize/tinyobjloader",
+    classifiers=["License :: OSI Approved :: MIT License"],
+    packages=setuptools.find_packages(),
+    ext_modules=[m],
+)