RF: Prefer alternate_exts over abusing files_types

Author: effigies

nibabel/filename_parser.py

@@ -131,8 +131,6 @@ def types_filenames(template_fname, types_exts,
         elif found_ext == found_ext.lower():
             proc_ext = lambda s: s.lower()
     for name, ext in types_exts:
-        if name in tfns:  # Allow multipe definitions of image, header, etc,
-            continue      # giving priority to those found first.
         if name == direct_set_name:
             tfns[name] = template_fname
             continue

nibabel/freesurfer/mghformat.py

@@ -459,8 +459,7 @@ class MGHImage(SpatialImage):
     """ Class for MGH format image
     """
     header_class = MGHHeader
-    files_types = (('image', '.mgh'),
-                   ('image', '.mgz'))
+    files_types = (('image', '.mgh'),)
     _compressed_exts = (('.gz',))
 
     makeable = True

nibabel/openers.py

@@ -160,7 +160,9 @@ class ImageOpener(Opener):
     def register_ext_from_image(opener_klass, ext, func_def):
         """Decorator for adding extension / opener_function associations.
 
-        Should be used to decorate classes.
+        Should be used to decorate classes. Updates ImageOpener class with
+        desired extension / opener association. Updates decorated class by
+        adding ```ext``` to ```klass.alternate_exts```.
 
         Parameters
         ----------
@@ -176,12 +178,12 @@ def register_ext_from_image(opener_klass, ext, func_def):
 
         Returns
         -------
-        opener_klass, with a side-effect of updating the ImageOpener class
-        with the desired extension / opener association.
+        opener_klass
         """
         def decorate(klass):
             assert ext not in opener_klass.compress_ext_map, \
                 "Cannot redefine extension-function mappings."
             opener_klass.compress_ext_map[ext] = func_def
+            klass.alternate_exts += (ext,)
             return klass
         return decorate

nibabel/spatialimages.py

@@ -325,6 +325,7 @@ class SpatialImage(object):
     ''' Template class for images '''
     header_class = Header
     files_types = (('image', None),)
+    alternate_exts = ()  # Modified by @ImageOpener.register_ext_from_image
     _compressed_exts = ()
 
     makeable = True  # Used in test code
@@ -874,7 +875,8 @@ def from_image(klass, img):
 
     @classmethod
     def is_valid_extension(klass, ext):
-        return np.any([ft[1] == ext.lower() for ft in klass.files_types])
+        valid = tuple(ft[1] for ft in klass.files_types) + klass.alternate_exts
+        return ext.lower() in valid
 
     @classmethod
     def path_maybe_image(klass, filename, sniff=None):

nibabel/tests/test_openers.py

@@ -90,6 +90,7 @@ def test_BinOpener():
                       BinOpener, 'test.txt', 'r')
 
 class TestImageOpener:
+    alternate_exts = ()
     def setUp(self):
         self.compress_ext_map = ImageOpener.compress_ext_map.copy()
 
@@ -115,6 +116,7 @@ def file_opener(fileish, mode):
         dec(self.__class__)
         assert_equal(n_associations + 1, len(ImageOpener.compress_ext_map))
         assert_true('.foo' in ImageOpener.compress_ext_map)
+        assert_true('.foo' in self.alternate_exts)
 
         with InTemporaryDirectory():
             with ImageOpener('test.foo', 'w'):