Check dependencies at runtime as declared in setup.py.

anntzer · anntzer · commit 4effa6f52caf · 2018-01-22T15:29:22.000-08:00
The goal is to list the requirements exactly once in code (in
setupext.py) and once in the docs (in INSTALL.rst).

Instead of manually importing and checking that (python) dependencies
are installed with the correct versions, rely on pkg_resources, which
allows automatically keeping things in sync with setupext, as well as
correctly check e.g. the complex version requirements on pyparsing.

Remove the overly complex way to specify the minimum numpy version.

Add comments reminding to update INSTALL.rst when the requirements are
changed in setupext.py; reorder dependencies in INSTALL.rst in a more
logical order.

Remove unneeded reference to MATLAB being a registered trademark.

Note that if you are running Matplotlib from source by manipulating
PYTHONPATH, then it will not appear to pkg_resources.  In this case,
there is no check for other dependencies (you are assumed to be
responsible enough for that).  Conversely, Matplotlib will fail to
import if it is installed into site-packages but some dependency (six,
etc.) is only available in PYTHONPATH instead of being correctly
installed.  I think this is acceptable (or we could just completely drop
the import checks and let bad installs fail with normal ImportErrors).
diff --git a/INSTALL.rst b/INSTALL.rst
@@ -168,20 +168,20 @@ Dependencies
 Matplotlib requires a large number of dependencies:
 
   * `Python <https://www.python.org/downloads/>`_ (>= 2.7 or >= 3.4)
-  * `NumPy <http://www.numpy.org>`_ (>= |minimum_numpy_version|)
-  * `setuptools <https://setuptools.readthedocs.io/en/latest/>`__
+  * `setuptools <https://setuptools.readthedocs.io/en/latest/>`_
+  * `NumPy <http://www.numpy.org>`_ (>= 1.7.1)
+  * `cycler <http://matplotlib.org/cycler/>`_ (>= 0.10.0)
   * `dateutil <https://pypi.python.org/pypi/python-dateutil>`_ (>= 2.1)
-  * `pyparsing <https://pyparsing.wikispaces.com/>`__
-  * `libpng <http://www.libpng.org>`__ (>= 1.2)
-  * `pytz <http://pytz.sourceforge.net/>`__
-  * FreeType (>= 2.3)
-  * `cycler <http://matplotlib.org/cycler/>`__ (>= 0.10.0)
-  * `six <https://pypi.python.org/pypi/six>`_
+  * `pyparsing <https://pyparsing.wikispaces.com/>`_ (>= 2.1.7; some older
+    versions may work)
+  * `pytz <http://pytz.sourceforge.net/>`_
+  * `six <https://pypi.python.org/pypi/six>`_ (>= 1.10)
   * `backports.functools_lru_cache <https://pypi.python.org/pypi/backports.functools_lru_cache>`_
     (for Python 2.7 only)
   * `subprocess32 <https://pypi.python.org/pypi/subprocess32/>`_ (for Python
     2.7 only, on Linux and macOS only)
-
+  * `FreeType <https://www.freetype.org>`_ (>= 2.3)
+  * `libpng <http://www.libpng.org>`_ (>= 1.2)
 
 Optionally, you can also install a number of packages to enable better user
 interface toolkits. See :ref:`what-is-a-backend` for more details on the
diff --git a/doc/conf.py b/doc/conf.py
@@ -322,10 +322,6 @@ def _check_deps():
 # documentation
 autoclass_content = 'both'
 
-rst_epilog = """
-.. |minimum_numpy_version| replace:: %s
-""" % matplotlib.__version__numpy__
-
 texinfo_documents = [
     ("contents", 'matplotlib', 'Matplotlib Documentation',
      'John Hunter@*Darren Dale@*Eric Firing@*Michael Droettboom@*'
diff --git a/lib/matplotlib/__init__.py b/lib/matplotlib/__init__.py
@@ -94,20 +94,29 @@
 
 matplotlib was initially written by John D. Hunter (1968-2012) and is now
 developed and maintained by a host of others.
-
-Occasionally the internal documentation (python docstrings) will refer
-to MATLAB&reg;, a registered trademark of The MathWorks, Inc.
-
 """
 from __future__ import absolute_import, division, print_function
 
+import pkg_resources
+
+try:
+    pkg_resources.get_distribution("matplotlib")
+except pkg_resources.DistributionNotFound:
+    # Running from source -- you're on your own.
+    pass
+else:
+    try:
+        # Check that dependencies are correctly installed.
+        pkg_resources.require("matplotlib")
+    except pkg_resources.ResolutionError as e:
+        raise ImportError("Matplotlib requires {}".format(e.req))
+
 import six
 
 import atexit
 from collections import MutableMapping
 import contextlib
-import distutils.version
-import distutils.sysconfig
+from distutils.version import LooseVersion
 import functools
 import io
 import inspect
@@ -122,17 +131,16 @@
 import tempfile
 import warnings
 
+from six.moves.urllib.request import urlopen
+from six.moves import reload_module as reload
+
 # cbook must import matplotlib only within function
 # definitions, so it is safe to import from it here.
 from . import cbook
-from matplotlib.cbook import (
+from .cbook import (
     _backports, mplDeprecation, dedent, get_label, sanitize_sequence)
-from matplotlib.compat import subprocess
-from matplotlib.rcsetup import defaultParams, validate_backend, cycler
-
-import numpy
-from six.moves.urllib.request import urlopen
-from six.moves import reload_module as reload
+from .compat import subprocess
+from .rcsetup import defaultParams, validate_backend, cycler
 
 # Get the version from the _version.py versioneer file. For a git checkout,
 # this is computed based on the number of commits since the last tag.
@@ -177,41 +185,11 @@ def compare_versions(a, b):
                 a = a.decode('ascii')
             if isinstance(b, bytes):
                 b = b.decode('ascii')
-        a = distutils.version.LooseVersion(a)
-        b = distutils.version.LooseVersion(b)
-        return a >= b
+        return LooseVersion(a) >= LooseVersion(b)
     else:
         return False
 
 
-try:
-    import dateutil
-except ImportError:
-    raise ImportError("Matplotlib requires dateutil")
-
-
-if not compare_versions(six.__version__, '1.10'):
-    raise ImportError(
-        "Matplotlib requires six>=1.10; you have %s" % six.__version__)
-
-
-try:
-    import pyparsing
-except ImportError:
-    raise ImportError("Matplotlib requires pyparsing")
-else:
-    if not compare_versions(pyparsing.__version__, '2.0.1'):
-        raise ImportError(
-            "Matplotlib requires pyparsing>=2.0.1; you have %s"
-            % pyparsing.__version__)
-
-
-if not compare_versions(numpy.__version__, __version__numpy__):
-    raise ImportError(
-        "Matplotlib requires numpy>=%s; you have %s" % (
-            __version__numpy__, numpy.__version__))
-
-
 if not hasattr(sys, 'argv'):  # for modpython
     sys.argv = [str('modpython')]
 
diff --git a/setupext.py b/setupext.py
@@ -119,18 +119,6 @@ def get_win32_compiler():
 win32_compiler = get_win32_compiler()
 
 
-def extract_versions():
-    """
-    Extracts version values from the main matplotlib __init__.py and
-    returns them as a dictionary.
-    """
-    with open('lib/matplotlib/__init__.py') as fd:
-        for line in fd.readlines():
-            if (line.startswith('__version__numpy__')):
-                exec(line.strip())
-    return locals()
-
-
 def has_include_file(include_dirs, filename):
     """
     Returns `True` if `filename` can be found in one of the
@@ -958,7 +946,8 @@ def include_dirs_hook():
         return [numpy.get_include()]
 
     def check(self):
-        min_version = extract_versions()['__version__numpy__']
+        # Remember to keep the version in INSTALL.rst in sync.
+        min_version = "1.7.1"
         try:
             import numpy
         except ImportError:
@@ -1429,6 +1418,7 @@ def check(self):
         return "handled by setuptools"
 
     def get_install_requires(self):
+        # Remember to keep the list in INSTALL.rst in sync.
         install_requires = [
             "cycler>=0.10",
             "pyparsing>=2.0.1,!=2.0.4,!=2.1.2,!=2.1.6",
