Merge pull request matplotlib#1762 from efiring/cbook_safe_import

Make cbook safe to import while removing duplicate is_string_like;

Author: efiring

lib/matplotlib/__init__.py

@@ -106,6 +106,11 @@
 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
+
 try:
     reload
 except NameError:
@@ -123,19 +128,6 @@
     sys.argv = ['modpython']
 
 
-class MatplotlibDeprecationWarning(UserWarning):
-    """
-    A class for issuing deprecation warnings for Matplotlib users.
-
-    In light of the fact that Python builtin DeprecationWarnings are ignored
-    by default as of Python 2.7 (see link below), this class was put in to
-    allow for the signaling of deprecation, but via UserWarnings which are not
-    ignored by default.
-
-    http://docs.python.org/dev/whatsnew/2.7.html#the-future-for-python-2-x
-    """
-    pass
-
 """
 Manage user customizations through a rc file.
 
@@ -192,12 +184,6 @@ def byte2str(b): return b
             __version__numpy__, numpy.__version__))
 del version
 
-def is_string_like(obj):
-    if hasattr(obj, 'shape'): return 0
-    try: obj + ''
-    except (TypeError, ValueError): return 0
-    return 1
-
 
 def _is_writable_dir(p):
     """

lib/matplotlib/cbook.py

@@ -1,7 +1,11 @@
 """
-A collection of utility functions and classes.  Many (but not all)
-from the Python Cookbook -- hence the name cbook
+A collection of utility functions and classes.  Originally, many 
+(but not all) were from the Python Cookbook -- hence the name cbook.
+
+This module is safe to import from anywhere within matplotlib;
+it imports matplotlib only at runtime.
 """
+
 from __future__ import print_function
 
 import datetime
@@ -18,18 +22,28 @@
 import threading
 import time
 import traceback
+import types
 import warnings
 from weakref import ref, WeakKeyDictionary
 
-import matplotlib
-from matplotlib import MatplotlibDeprecationWarning as mplDeprecation
-
 import numpy as np
 import numpy.ma as ma
 
 
-import types
+class MatplotlibDeprecationWarning(UserWarning):
+    """
+    A class for issuing deprecation warnings for Matplotlib users.
 
+    In light of the fact that Python builtin DeprecationWarnings are ignored
+    by default as of Python 2.7 (see link below), this class was put in to
+    allow for the signaling of deprecation, but via UserWarnings which are not
+    ignored by default.
+
+    http://docs.python.org/dev/whatsnew/2.7.html#the-future-for-python-2-x
+    """
+    pass
+
+mplDeprecation = MatplotlibDeprecationWarning
 
 # On some systems, locale.getpreferredencoding returns None,
 # which can break unicode; and the sage project reports that
@@ -42,6 +56,8 @@
 
 if sys.version_info[0] >= 3:
     def unicode_safe(s):
+        import matplotlib
+
         try:
             preferredencoding = locale.getpreferredencoding(
                 matplotlib.rcParams['axes.formatter.use_locale']).strip()
@@ -576,6 +592,8 @@ def get_sample_data(fname, asfileobj=True):
 
     If the filename ends in .gz, the file is implicitly ungzipped.
     """
+    import matplotlib
+
     if matplotlib.rcParams['examples.directory']:
         root = matplotlib.rcParams['examples.directory']
     else: