Merge #190

190: Drop compatiblity with Python 3.6 r=astraluma a=nbraud

We only aim to support the last 2 major versions of Python (currently 3.7 and 3.8), and the `dataclasses` backport for Python 3.6 is unmaintained and broken (see discussion in #184).

This should allow us to unblock #168 

Co-authored-by: Nicolas Braud-Santoni <nicolas@braud-santoni.eu>
Co-authored-by: Jamie Bliss <jamie@ivyleav.es>

.cirrus.yml

@@ -67,7 +67,6 @@ FreeBSD_task:
     image_family: freebsd-12-1
   env:
     matrix:
-      - PYTHON: 3.6
       - PYTHON: 3.7
       - PYTHON: 3.8
       - PYTHON: 3.9
@@ -90,12 +89,10 @@ task:
   skip: $CIRRUS_BRANCH =~ '.*\.tmp'
   env:
     matrix:
-      - IMAGE: python:3.6-slim
       - IMAGE: python:3.7-slim
       - IMAGE: python:3.8-slim
       - IMAGE: python:3.9-slim
       - IMAGE: python:3.10-rc-slim
-      - IMAGE: pypy:3.6-slim
       - IMAGE: pypy:3.7-slim
   name: "Linux $IMAGE"
   allow_failures: $IMAGE =~ '.*-rc-.*'
@@ -119,7 +116,6 @@ macOS_task:
   env:
     PATH: ${HOME}/.pyenv/shims:${PATH}
     matrix:
-      - PYTHON: 3.6.12
       - PYTHON: 3.7.7
       - PYTHON: 3.8.6
       - PYTHON: 3.9.0
@@ -143,7 +139,6 @@ task:
   skip: $CIRRUS_BRANCH =~ '.*\.tmp'
   env:
     matrix:
-      - IMAGE: python:3.6-windowsservercore
       - IMAGE: python:3.7-windowsservercore
       - IMAGE: python:3.8-windowsservercore
       - IMAGE: python:3.9-windowsservercore

bors.toml

@@ -1,19 +1,15 @@
 status = [
   "docs",
-  "FreeBSD PYTHON:3.6",
   "FreeBSD PYTHON:3.7",
   "FreeBSD PYTHON:3.8",
   "FreeBSD PYTHON:3.9",
   "lint",
-  "Linux python:3.6-slim",
   "Linux python:3.7-slim",
   "Linux python:3.8-slim",
   "Linux python:3.9-slim",
-  "Windows python:3.6-windowsservercore",
   "Windows python:3.7-windowsservercore",
   "Windows python:3.8-windowsservercore",
   "Windows python:3.9-windowsservercore",
-  "macOS PYTHON:3.6.12",
   "macOS PYTHON:3.7.7",
   "macOS PYTHON:3.8.6",
   "macOS PYTHON:3.9.0",

ppb_vector/__init__.py

@@ -118,12 +118,12 @@ def __new__(cls, *args, **kwargs):
             #  https://docs.python.org/3/library/dataclasses.html#frozen-instances
             object.__setattr__(self, 'x', float(x))
         except ValueError:
-            raise TypeError(f"{type(x).__name__} object not convertable to float")
+            raise TypeError(f"{type(x).__name__} object not convertable to float") from None
 
         try:
             object.__setattr__(self, 'y', float(y))
         except ValueError:
-            raise TypeError(f"{type(y).__name__} object not convertable to float")
+            raise TypeError(f"{type(y).__name__} object not convertable to float") from None
 
         return self
 

setup.cfg

@@ -15,13 +15,12 @@ classifiers =
     Topic :: Software Development :: Libraries
     Topic :: Scientific/Engineering :: Mathematics
     Programming Language :: Python :: 3
-    Programming Language :: Python :: 3.6
     Programming Language :: Python :: 3.7
     Programming Language :: Python :: 3.8
 
 [options]
 packages = ppb_vector
-python_requires = >= 3.6
+python_requires = >= 3.7
 zip_safe = True
 
 [aliases]

setup.py

@@ -16,7 +16,6 @@ def requirements(section=None):
 # See setup.cfg for the actual configuration.
 setup(
     # setup needs to be able to import the library, for attr: to work
-    setup_requires=requirements() + ['pytest-runner'],
-    install_requires=requirements(),
+    setup_requires=['pytest-runner'],
     tests_require=requirements('tests'),
 )