matplotlib · pelson · Mar 20, 2013 · Mar 12, 2013 · Mar 12, 2013 · Mar 12, 2013
diff --git a/doc/api/api_changes.rst b/doc/api/api_changes.rst
@@ -32,6 +32,13 @@ Changes in 1.3.x
   by ``self.vline`` for vertical cursors lines and ``self.hline`` is added
   for the horizontal cursors lines.
 
+* On POSIX platforms, the :func:`~matplotlib.cbook.report_memory` function
+  raises :class:`NotImplementedError` instead of :class:`OSError` if the
+  :command:`ps` command cannot be run.
+
+* The :func:`~matplotlib.cbook.check_output` function has been moved to
+  `~matplotlib.compat.subprocess`.
+
 Changes in 1.2.x
 ================
 

diff --git a/lib/matplotlib/__init__.py b/lib/matplotlib/__init__.py
@@ -124,14 +124,15 @@
                 '.'.join(str(x) for x in _required),
                 sys.version_info[0]))
 
-import os, re, shutil, subprocess, warnings
+import os, re, shutil, warnings
 import distutils.sysconfig
 import distutils.version
 
 # cbook must import matplotlib only within function
 # definitions, so it is safe to import from it here.
 from matplotlib.cbook import MatplotlibDeprecationWarning
 from matplotlib.cbook import is_string_like
+from matplotlib.compat import subprocess
 
 try:
     reload

diff --git a/lib/matplotlib/animation.py b/lib/matplotlib/animation.py
@@ -20,8 +20,8 @@
 import sys
 import itertools
 import contextlib
-import subprocess
 from matplotlib.cbook import iterable, is_string_like
+from matplotlib.compat import subprocess
 from matplotlib import verbose
 from matplotlib import rcParams
 

diff --git a/lib/matplotlib/backends/backend_pgf.py b/lib/matplotlib/backends/backend_pgf.py
@@ -7,7 +7,6 @@
 import shutil
 import tempfile
 import codecs
-import subprocess
 import atexit
 import weakref
 
@@ -21,7 +20,8 @@
 from matplotlib import font_manager
 from matplotlib.ft2font import FT2Font
 from matplotlib.cbook import is_string_like, is_writable_file_like
-from matplotlib.cbook import check_output
+from matplotlib.compat import subprocess
+from matplotlib.compat.subprocess import check_output
 
 
 ###############################################################################

diff --git a/lib/matplotlib/backends/backend_ps.py b/lib/matplotlib/backends/backend_ps.py
@@ -88,7 +88,7 @@ def gs_version(self):
         except KeyError:
             pass
 
-        from subprocess import Popen, PIPE
+        from matplotlib.compat.subprocess import Popen, PIPE
         pipe = Popen(self.gs_exe + " --version",
                      shell=True, stdout=PIPE).stdout
         if sys.version_info[0] >= 3:

diff --git a/lib/matplotlib/cbook.py b/lib/matplotlib/cbook.py
@@ -17,7 +17,6 @@
 import locale
 import os
 import re
-import subprocess
 import sys
 import threading
 import time
@@ -1212,19 +1211,34 @@ def restrict_dict(d, keys):
 
 def report_memory(i=0):  # argument may go away
     'return the memory consumed by process'
-    from subprocess import Popen, PIPE
+    from matplotlib.compat.subprocess import Popen, PIPE
     pid = os.getpid()
     if sys.platform == 'sunos5':
-        a2 = Popen('ps -p %d -o osz' % pid, shell=True,
-                   stdout=PIPE).stdout.readlines()
+        try:
+            a2 = Popen('ps -p %d -o osz' % pid, shell=True,
+                       stdout=PIPE).stdout.readlines()
+        except OSError:
+            raise NotImplementedError(
+                "report_memory works on Sun OS only if "
+                "the 'ps' program is found")
         mem = int(a2[-1].strip())
     elif sys.platform.startswith('linux'):
-        a2 = Popen('ps -p %d -o rss,sz' % pid, shell=True,
-                   stdout=PIPE).stdout.readlines()
+        try:
+            a2 = Popen('ps -p %d -o rss,sz' % pid, shell=True,
+                       stdout=PIPE).stdout.readlines()
+        except OSError:
+            raise NotImplementedError(
+                "report_memory works on Linux only if "
+                "the 'ps' program is found")
         mem = int(a2[1].split()[1])
     elif sys.platform.startswith('darwin'):
-        a2 = Popen('ps -p %d -o rss,vsz' % pid, shell=True,
-                   stdout=PIPE).stdout.readlines()
+        try:
+            a2 = Popen('ps -p %d -o rss,vsz' % pid, shell=True,
+                       stdout=PIPE).stdout.readlines()
+        except OSError:
+            raise NotImplementedError(
+                "report_memory works on Mac OS only if "
+                "the 'ps' program is found")
         mem = int(a2[1].split()[0])
     elif sys.platform.startswith('win'):
         try:
@@ -1795,45 +1809,3 @@ def get_instancemethod(self):
 else:
     def _putmask(a, mask, values):
         return np.copyto(a, values, where=mask)
-
-
-def _check_output(*popenargs, **kwargs):
-    r"""Run command with arguments and return its output as a byte
-    string.
-
-    If the exit code was non-zero it raises a CalledProcessError.  The
-    CalledProcessError object will have the return code in the
-    returncode
-    attribute and output in the output attribute.
-
-    The arguments are the same as for the Popen constructor.  Example::
-
-    >>> check_output(["ls", "-l", "/dev/null"])
-    'crw-rw-rw- 1 root root 1, 3 Oct 18  2007 /dev/null\n'
-
-    The stdout argument is not allowed as it is used internally.
-    To capture standard error in the result, use stderr=STDOUT.::
-
-    >>> check_output(["/bin/sh", "-c",
-    ...               "ls -l non_existent_file ; exit 0"],
-    ...              stderr=STDOUT)
-    'ls: non_existent_file: No such file or directory\n'
-    """
-    if 'stdout' in kwargs:
-        raise ValueError('stdout argument not allowed, it will be overridden.')
-    process = subprocess.Popen(stdout=subprocess.PIPE, *popenargs, **kwargs)
-    output, unused_err = process.communicate()
-    retcode = process.poll()
-    if retcode:
-        cmd = kwargs.get("args")
-        if cmd is None:
-            cmd = popenargs[0]
-        raise subprocess.CalledProcessError(retcode, cmd, output=output)
-    return output
-
-
-# python2.7's subprocess provides a check_output method
-if hasattr(subprocess, 'check_output'):
-    check_output = subprocess.check_output
-else:
-    check_output = _check_output
diff --git a/lib/matplotlib/compat/__init__.py b/lib/matplotlib/compat/__init__.py
diff --git a/lib/matplotlib/compat/subprocess.py b/lib/matplotlib/compat/subprocess.py
@@ -0,0 +1,77 @@
+"""
+A replacement wrapper around the subprocess module, with a number of
+work-arounds:
+- Provides the check_output function (which subprocess only provides from Python
+  2.7 onwards).
+- Provides a stub implementation of subprocess members on Google App Engine
+  (which are missing in subprocess).
+
+Instead of importing subprocess, other modules should use this as follows:
+
+from matplotlib.compat import subprocess
+
+This module is safe to import from anywhere within matplotlib.
+"""
+
+from __future__ import absolute_import    # Required to import subprocess
+from __future__ import print_function
+
+import subprocess
+
+__all__ = ['Popen', 'PIPE', 'STDOUT', 'check_output']
+
+
+if hasattr(subprocess, 'Popen'):
+    Popen = subprocess.Popen
+    # Assume that it also has the other constants.
+    PIPE = subprocess.PIPE
+    STDOUT = subprocess.STDOUT
+else:
+    # In restricted environments (such as Google App Engine), these are
+    # non-existent. Replace them with dummy versions that always raise OSError.
+    def Popen(*args, **kwargs):
+        raise OSError("subprocess.Popen is not supported")
+    PIPE = -1
+    STDOUT = -2
+
+
+def _check_output(*popenargs, **kwargs):
+    r"""Run command with arguments and return its output as a byte
+    string.
+
+    If the exit code was non-zero it raises a CalledProcessError.  The
+    CalledProcessError object will have the return code in the
+    returncode
+    attribute and output in the output attribute.
+
+    The arguments are the same as for the Popen constructor.  Example::
+
+    >>> check_output(["ls", "-l", "/dev/null"])
+    'crw-rw-rw- 1 root root 1, 3 Oct 18  2007 /dev/null\n'
+
+    The stdout argument is not allowed as it is used internally.
+    To capture standard error in the result, use stderr=STDOUT.::
+
+    >>> check_output(["/bin/sh", "-c",
+    ...               "ls -l non_existent_file ; exit 0"],
+    ...              stderr=STDOUT)
+    'ls: non_existent_file: No such file or directory\n'
+    """
+    if 'stdout' in kwargs:
+        raise ValueError('stdout argument not allowed, it will be overridden.')
+    process = Popen(stdout=PIPE, *popenargs, **kwargs)
+    output, unused_err = process.communicate()
+    retcode = process.poll()
+    if retcode:
+        cmd = kwargs.get("args")
+        if cmd is None:
+            cmd = popenargs[0]
+        raise subprocess.CalledProcessError(retcode, cmd, output=output)
+    return output
+
+
+# python2.7's subprocess provides a check_output method
+if hasattr(subprocess, 'check_output'):
+    check_output = subprocess.check_output
+else:
+    check_output = _check_output
diff --git a/lib/matplotlib/dviread.py b/lib/matplotlib/dviread.py
@@ -23,9 +23,9 @@
 import errno
 import matplotlib
 import matplotlib.cbook as mpl_cbook
+from matplotlib.compat import subprocess
 import numpy as np
 import struct
-import subprocess
 import sys
 
 if sys.version_info[0] >= 3:

diff --git a/lib/matplotlib/font_manager.py b/lib/matplotlib/font_manager.py
@@ -43,7 +43,7 @@
             see license/LICENSE_TTFQUERY.
 """
 
-import os, sys, subprocess, warnings
+import os, sys, warnings
 try:
     set
 except NameError:
@@ -54,6 +54,7 @@
 from matplotlib import rcParams, get_configdir
 from matplotlib.cbook import is_string_like
 import matplotlib.cbook as cbook
+from matplotlib.compat import subprocess
 from matplotlib.fontconfig_pattern import \
     parse_fontconfig_pattern, generate_fontconfig_pattern
 

diff --git a/lib/matplotlib/testing/compare.py b/lib/matplotlib/testing/compare.py
@@ -7,6 +7,7 @@
 from __future__ import division
 
 import matplotlib
+from matplotlib.compat import subprocess
 from matplotlib.testing.noseclasses import ImageComparisonFailure
 from matplotlib.testing import image_util, util
 from matplotlib import _png
@@ -17,7 +18,6 @@
 import os
 import numpy as np
 import shutil
-import subprocess
 import sys
 from functools import reduce
 

diff --git a/lib/matplotlib/testing/util.py b/lib/matplotlib/testing/util.py
@@ -1,5 +1,5 @@
-import subprocess
 import sys
+from matplotlib.compat import subprocess
 
 
 class MiniExpect:

diff --git a/lib/matplotlib/tests/test_backend_pgf.py b/lib/matplotlib/tests/test_backend_pgf.py
@@ -2,12 +2,12 @@
 
 import os
 import shutil
-import subprocess
 import numpy as np
 import nose
 from nose.plugins.skip import SkipTest
 import matplotlib as mpl
 import matplotlib.pyplot as plt
+from matplotlib.compat import subprocess
 from matplotlib.testing.compare import compare_images, ImageComparisonFailure
 from matplotlib.testing.decorators import _image_directories
 

diff --git a/lib/matplotlib/texmanager.py b/lib/matplotlib/texmanager.py
@@ -41,7 +41,6 @@
 import os
 import shutil
 import sys
-from subprocess import Popen, PIPE, STDOUT
 
 from hashlib import md5
 
@@ -51,6 +50,7 @@
 from matplotlib import rcParams
 from matplotlib._png import read_png
 from matplotlib.cbook import mkdirs
+from matplotlib.compat.subprocess import Popen, PIPE, STDOUT
 import matplotlib.dviread as dviread
 import re
 
@@ -63,8 +63,12 @@
 
 
 def dvipng_hack_alpha():
-    p = Popen('dvipng -version', shell=True, stdin=PIPE, stdout=PIPE,
-              stderr=STDOUT, close_fds=(sys.platform != 'win32'))
+    try:
+        p = Popen('dvipng -version', stdin=PIPE, stdout=PIPE, stderr=STDOUT,
+                  close_fds=(sys.platform != 'win32'))
+    except OSError:
+        mpl.verbose.report('No dvipng was found', 'helpful')
+        return False
     stdin, stdout = p.stdin, p.stdout
     for line in stdout:
         if line.startswith(b'dvipng '):
@@ -74,7 +78,7 @@ def dvipng_hack_alpha():
             version = version.decode('ascii')
             version = distutils.version.LooseVersion(version)
             return version < distutils.version.LooseVersion('1.6')
-    mpl.verbose.report('No dvipng was found', 'helpful')
+    mpl.verbose.report('Unexpected response from dvipng -version', 'helpful')
     return False
 
 

diff --git a/setupext.py b/setupext.py
@@ -494,6 +494,7 @@ def get_packages(self):
             'matplotlib',
             'matplotlib.backends',
             'matplotlib.backends.qt4_editor',
+            'matplotlib.compat',
             'matplotlib.projections',
             'matplotlib.sphinxext',
             'matplotlib.testing',