FIX: Do not cache grab_exts

Author: effigies

nipype/interfaces/base/traits_extension.py

@@ -214,26 +214,19 @@ def __init__(self,
         """
         self.types = types
         self.allow_compressed = allow_compressed
-        self._exts = None
         super(ImageFile, self).__init__(value, filter, auto_set, entries,
                                         exists, **metadata)
 
     def info(self):
-        existing='n existing' if self.exists else ''
+        existing = 'n existing' if self.exists else ''
         comma = ',' if self.exists and not self.allow_compressed else ''
-        uncompressed=' uncompressed' if not self.allow_compressed else ''
-        with_ext = ' (valid extensions: [{}])'.format(', '.join(self.exts)) \
-            if self.types else ''
+        uncompressed = ' uncompressed' if not self.allow_compressed else ''
+        with_ext = ' (valid extensions: [{}])'.format(
+            ', '.join(self.grab_exts())) if self.types else ''
         return 'a{existing}{comma}{uncompressed} file{with_ext}'.format(
             existing=existing, comma=comma, uncompressed=uncompressed,
             with_ext=with_ext)
 
-    @property
-    def exts(self):
-        if self.types and self._exts is None:
-            self._exts = self.grab_exts()
-        return self._exts
-
     def grab_exts(self):
         # TODO: file type validation
         exts = []
@@ -260,10 +253,11 @@ def validate(self, object, name, value):
         """
         validated_value = super(ImageFile, self).validate(object, name, value)
         if validated_value and self.types:
-            if not any(validated_value.endswith(x) for x in self.exts):
+            _exts = self.grab_exts()
+            if not any(validated_value.endswith(x) for x in _exts):
                 raise TraitError(
                     args="{} is not included in allowed types: {}".format(
-                        validated_value, ', '.join(self.exts)))
+                        validated_value, ', '.join(_exts)))
         return validated_value