From b8c30bad4699e13a2c9a3eb055e11cf04990bae3 Mon Sep 17 00:00:00 2001
From: Tony S Yu <tsyu80@gmail.com>
Date: Mon, 18 Nov 2013 21:15:04 -0600
Subject: [PATCH] Move image stack to its own module

---
 skimage/io/__init__.py     |  1 +
 skimage/io/_image_stack.py | 35 +++++++++++++++++++++++++++++++++++
 skimage/io/_io.py          | 38 ++++----------------------------------
 3 files changed, 40 insertions(+), 34 deletions(-)
 create mode 100644 skimage/io/_image_stack.py

diff --git a/skimage/io/__init__.py b/skimage/io/__init__.py
index 5e701a51..a2553c54 100644
--- a/skimage/io/__init__.py
+++ b/skimage/io/__init__.py
@@ -14,6 +14,7 @@ from .sift import *
 from .collection import *
 
 from ._io import *
+from ._image_stack import *
 from .video import *
 
 
diff --git a/skimage/io/_image_stack.py b/skimage/io/_image_stack.py
new file mode 100644
index 00000000..ca9896d5
--- /dev/null
+++ b/skimage/io/_image_stack.py
@@ -0,0 +1,35 @@
+import numpy as np
+
+
+__all__ = ['image_stack', 'push', 'pop']
+
+
+# Shared image queue
+image_stack = []
+
+
+def push(img):
+    """Push an image onto the shared image stack.
+
+    Parameters
+    ----------
+    img : ndarray
+        Image to push.
+
+    """
+    if not isinstance(img, np.ndarray):
+        raise ValueError("Can only push ndarrays to the image stack.")
+
+    image_stack.append(img)
+
+
+def pop():
+    """Pop an image from the shared image stack.
+
+    Returns
+    -------
+    img : ndarray
+        Image popped from the stack.
+
+    """
+    return image_stack.pop()
diff --git a/skimage/io/_io.py b/skimage/io/_io.py
index eb704a6f..ae05ea77 100644
--- a/skimage/io/_io.py
+++ b/skimage/io/_io.py
@@ -1,10 +1,7 @@
-__all__ = ['Image', 'imread', 'imread_collection', 'imsave', 'imshow', 'show',
-           'push', 'pop']
-
 try:
-    from urllib.request import urlopen
+    from urllib.request import urlopen  # Python 3
 except ImportError:
-    from urllib2 import urlopen
+    from urllib2 import urlopen  # Python 2
 
 import os
 import re
@@ -19,8 +16,8 @@ from skimage.color import rgb2grey
 
 
 
-# Shared image queue
-_image_stack = []
+__all__ = ['Image', 'imread', 'imread_collection', 'imsave', 'imshow', 'show']
+
 
 URL_REGEX = re.compile(r'http://|https://|ftp://|file://|file:\\')
 
@@ -77,33 +74,6 @@ class Image(np.ndarray):
         return return_str
 
 
-def push(img):
-    """Push an image onto the shared image stack.
-
-    Parameters
-    ----------
-    img : ndarray
-        Image to push.
-
-    """
-    if not isinstance(img, np.ndarray):
-        raise ValueError("Can only push ndarrays to the image stack.")
-
-    _image_stack.append(img)
-
-
-def pop():
-    """Pop an image from the shared image stack.
-
-    Returns
-    -------
-    img : ndarray
-        Image popped from the stack.
-
-    """
-    return _image_stack.pop()
-
-
 def imread(fname, as_grey=False, plugin=None, flatten=None,
            **plugin_args):
     """Load an image from file.