_environment_check.py

from __future__ import absolute_import
import os
import sys
import warnings

import numpy.distutils.system_info


def _check_python_350():
    if sys.version_info[:3] == (3, 5, 0):
        if not int(os.getenv('CHAINER_PYTHON_350_FORCE', '0')):
            msg = """
    Chainer does not work with Python 3.5.0.

    We strongly recommend to use another version of Python.
    If you want to use Chainer with Python 3.5.0 at your own risk,
    set 1 to CHAINER_PYTHON_350_FORCE environment variable."""

            raise Exception(msg)


def _check_python_2():
    if sys.version_info[:1] == (2,):
        warnings.warn('''
--------------------------------------------------------------------------------
Chainer is going to stop supporting Python 2 in v7.x releases.

Future releases of Chainer v7.x will not run on Python 2.
If you need to continue using Python 2, consider using Chainer v6.x, which
will be the last version that runs on Python 2.
--------------------------------------------------------------------------------
''')  # NOQA


def _check_osx_numpy_backend():
    if sys.platform != 'darwin':
        return

    blas_opt_info = numpy.distutils.system_info.get_info('blas_opt')
    if blas_opt_info:
        extra_link_args = blas_opt_info.get('extra_link_args')
        if extra_link_args and '-Wl,Accelerate' in extra_link_args:
            warnings.warn('''\
Accelerate has been detected as a NumPy backend library.
vecLib, which is a part of Accelerate, is known not to work correctly with Chainer.
We recommend using other BLAS libraries such as OpenBLAS.
For details of the issue, please see
https://docs.chainer.org/en/stable/tips.html#mnist-example-does-not-converge-in-cpu-mode-on-mac-os-x.

Please be aware that Mac OS X is not an officially supported OS.
''')  # NOQA


def check():
    _check_python_2()
    _check_python_350()
    _check_osx_numpy_backend()