Added caching to field.shape

nifty/field.py

@@ -112,7 +112,6 @@ class Field(Loggable, Versionable, object):
 
     def __init__(self, domain=None, val=None, dtype=None,
                  distribution_strategy=None, copy=False):
-
         self.domain = self._parse_domain(domain=domain, val=val)
         self.domain_axes = self._get_axes_tuple(self.domain)
 
@@ -128,6 +127,7 @@ class Field(Loggable, Versionable, object):
         else:
             self.set_val(new_val=val, copy=copy)
 
+
     def _parse_domain(self, domain, val=None):
         if domain is None:
             if isinstance(val, Field):
@@ -775,14 +775,14 @@ class Field(Loggable, Versionable, object):
         dim
 
         """
-
-        shape_tuple = tuple(sp.shape for sp in self.domain)
-        try:
-            global_shape = reduce(lambda x, y: x + y, shape_tuple)
-        except TypeError:
-            global_shape = ()
-
-        return global_shape
+        if not hasattr(self, '_shape'):
+            shape_tuple = tuple(sp.shape for sp in self.domain)
+            try:
+                global_shape = reduce(lambda x, y: x + y, shape_tuple)
+            except TypeError:
+                global_shape = ()
+            self._shape = global_shape
+        return self._shape
 
     @property
     def dim(self):