Introduce pyproject.toml

Using pyproject.toml, defined in PEP518, allows us to have
an isolated build environment, ensuring that Cython can be installed
before calling setup.py in tox. This allows us to use cython helpers
in the setup.py script.

This is a prerequisite for introducing Cython in the codebase

5 files changed, 24 insertions, 2 deletions

diff --git a/.gitignore b/.gitignore
index 3bc4e29af..340d7ebe4 100644
--- a/.gitignore
+++ b/.gitignore
@@ -8,6 +8,9 @@ build
 # Setuptools distribution folder.
 /dist/
 
+# Pip build metadata
+pip-wheel-metadata/
+
 # Python egg metadata, regenerated from source files by setuptools.
 /src/*.egg-info
 .eggs
diff --git a/MANIFEST.in b/MANIFEST.in
index d0de0e593..7be35c0be 100644
--- a/MANIFEST.in
+++ b/MANIFEST.in
@@ -43,3 +43,6 @@ include requirements/plugin-requirements.txt
 
 # Versioneer
 include versioneer.py
+
+# setuptools.build_meta don't include setup.py by default. Add it
+include setup.py
diff --git a/pyproject.toml b/pyproject.toml
new file mode 100644
index 000000000..38bb870e3
--- /dev/null
+++ b/pyproject.toml
@@ -0,0 +1,8 @@
+[build-system]
+requires = [
+    # We need at least version 36.6.0 that introduced "build_meta"
+    "setuptools>=36.6.0",
+    # In order to build wheels, and as required by PEP 517
+    "wheel"
+]
+build-backend = "setuptools.build_meta"
diff --git a/setup.py b/setup.py
index 267ca6fb4..0caf7bae9 100755
--- a/setup.py
+++ b/setup.py
@@ -19,13 +19,15 @@
 #        Tristan Van Berkom <tristan.vanberkom@codethink.co.uk>
 
 import os
+from pathlib import Path
 import re
 import shutil
 import subprocess
 import sys
-import versioneer
 
-from pathlib import Path
+# Add local directory to the path, in order to be able to import versioneer
+sys.path.append(os.path.dirname(__file__))
+import versioneer  # noqa
 
 
 ##################################################################
diff --git a/tox.ini b/tox.ini
index a7a4874c7..0a269c17d 100644
--- a/tox.ini
+++ b/tox.ini
@@ -4,6 +4,7 @@
 [tox]
 envlist = py{35,36,37}
 skip_missing_interpreters = true
+isolated_build = true
 
 #
 # Defaults for all environments
@@ -147,3 +148,8 @@ deps =
     -rrequirements/requirements.txt
     -rrequirements/dev-requirements.txt
     -rrequirements/plugin-requirements.txt
+
+# When building using PEP518 and 517, we don't want default dependencies
+# installed by the base environment.
+[testenv:.package]
+deps =