Second part of I/O infrastructure reorganisation.

scikits/image/io/_plugins/matplotlib_plugin.py

@@ -2,7 +2,7 @@ import plugin
 
 try:
     import matplotlib.pyplot as plt
-except ImportError:
-    pass
+except ImportError, e:
+    print e
 else:
     plugin.register('matplotlib', show=plt.imshow, save=plt.imsave)

scikits/image/io/_plugins/pil_plugin.py

@@ -1,7 +1,7 @@
 __all__ = ['imread']
 
-import numpy as np
 import plugin
+import numpy as np
 
 try:
     from PIL import Image
@@ -51,4 +51,4 @@ def palette_is_grayscale(pil_image):
 
 
 if has_pil:
-    plugin.register('PIL', read=imread)
+    plugin.register('pil', read=imread)

scikits/image/io/_plugins/plugin.py

@@ -2,7 +2,7 @@
 
 """
 
-__all__ = ['register', 'use']
+__all__ = ['register', 'use', 'load', 'available', 'call']
 
 import warnings
 
@@ -38,7 +38,7 @@ def register(name, **kwds):
         if not callable(func):
             raise ValueError('Can only register functions as plugins.')
 
-        plugin_store[kind].append((name, func))
+        plugin_store[kind].insert(0, (name, func))
 
 
 def call(kind, *args, **kwargs):
@@ -60,7 +60,11 @@ def call(kind, *args, **kwargs):
 
     plugin_funcs = plugin_store[kind]
     if len(plugin_funcs) == 0:
-        raise RuntimeError('No suitable plugin registered for %s' % kind)
+        raise RuntimeError('''No suitable plugin registered for %s.
+
+You may load I/O plugins with the `scikits.image.io.load_plugin`
+command.  A list of all available plugins can be found using
+`scikits.image.io.plugins()`.''' % kind)
 
     plugin = kwargs.pop('plugin', None)
     if plugin is None:
@@ -123,8 +127,9 @@ def available(kind=None):
     Parameters
     ----------
     kind : {'show', 'save', 'read'}, optional
-        Display the plugin list for the given function type.  If not specified,
-        return a dictionary with the plugins for all functions.
+        Display the plugin list for the given function type.  If not
+        specified, return a dictionary with the plugins for all
+        functions.
 
     """
     if kind is None:
@@ -141,3 +146,21 @@ def available(kind=None):
         d[k] = [name for (name, func) in plugin_store[k]]
 
     return d
+
+def load(plugin):
+    """Load the given plugin.
+
+    Parameters
+    ----------
+    plugin : str
+        Name of plugin to load.
+
+    See Also
+    --------
+    plugins : List of available plugins
+
+    """
+    try:
+        __import__('scikits.image.io._plugins.' + plugin + "_plugin")
+    except ImportError:
+        raise ValueError('Plugin %s not found.' % plugin)

scikits/image/io/_plugins/qt_plugin.py

@@ -1,5 +1,5 @@
 import plugin
-from _plugin_util import prepare_for_display
+from util import prepare_for_display
 
 import numpy as np
 import sys
@@ -37,7 +37,7 @@ else:
     def show(arr, block=True):
         global app
 
-        if not '-q4thread' in sys.argv and app is None:
+        if not '-qt4thread' in sys.argv and app is None:
             app = QApplication([])
 
         arr = prepare_for_display(arr)

scikits/image/io/_plugins/wx_plugin.py

@@ -1,6 +1,6 @@
 import numpy as np
 import plugin
-from _plugin_util import prepare_for_display
+from util import prepare_for_display
 
 try:
     import wx