allow directly assign OfG inst overriding grad/rop

theano/compile/builders.py

@@ -29,7 +29,8 @@ class OpFromGraph(gof.Op):
     inline: bool, optional
         if True, will cause the Op's original graph being used during
         compilation, otherwise will use a pre-compiled function inside.
-    grad_overrides: None | undef | function | list of (None|undef|function), optional
+    grad_overrides: None | undef | OpFromGraph instance | function | \
+        list of (None|undef|function), optional
         Used to override default gradient routine.
         Overriding function(s) must take two list of variable(s) as inputs,
         the original inputs and ups gradients
@@ -37,11 +38,15 @@ class OpFromGraph(gof.Op):
 
         - `None` : will use default gradient routine.
         - theano.utils.undef : No gradient will be used (zero)
+        - OpFromGraph instance: the OfG instance should accept inputs with same
+            order and types as specified in "inputs" and "outputs" arguments
         - function : must return list of Variable.
         - list : each function must return a single Variable. The order
             of the list must corresponds to inputs
-    rop_overrides: None | undef | function | list of (None|undef|function), optional
-        similar to grad_overrides, list order should match output instead
+    rop_overrides: None | undef | OpFromGraph instance | function | \
+        list of (None|undef|function), optional
+        similar to grad_overrides, list order should match two list of "inputs"
+        concatenated.
 
     TODO:
         - examples for a multi-layer mlp. where?
@@ -169,6 +174,9 @@ class OpFromGraph(gof.Op):
         return hash(type(self))
 
     def _recompute_grad_op(self):
+        if isinstance(self._grad_op, OpFromGraph):
+            self._grad_op_is_cached = True
+            return
         output_grads = [out_t() for out_t in self.output_types]
         if self._grad_op is None:
             self._grad_op = []
@@ -226,6 +234,9 @@ class OpFromGraph(gof.Op):
         self._grad_op_is_cached = True
 
     def _recompute_rop_op(self):
+        if isinstance(self._rop_op, OpFromGraph):
+            self._rop_op_is_cached = True
+            return
         eval_points = [inp_t() for inp_t in self.input_types]
         if self._rop_op is None:
             self._rop_op = []

theano/compile/tests/test_builders.py

@@ -126,14 +126,19 @@ class T_OpFromGraph(unittest_tools.InferShapeTester):
 
         def go(inps, gs):
             x, y = inps
-            g = gs[0]
+            g, = gs
             return [g * y * 2, g * x * 1.5]
-        # no override case is coverd in "grad" test
 
-        # single override case
+        dedz = T.vector('dedz')
+        op_mul_grad = cls_ofg([x, y, dedz], go([x, y], [dedz]))
+
         op_mul = cls_ofg([x, y], [x * y], grad_overrides=go)
+        op_mul2 = cls_ofg([x, y], [x * y], grad_overrides=op_mul_grad)
+
+        # single override case (function or OfG instance)
         xx, yy = T.vector('xx'), T.vector('yy')
-        zz = T.sum(op_mul(xx, yy))
+        for op in [op_mul, op_mul2]:
+            zz = T.sum(op(xx, yy))
             dx, dy = T.grad(zz, [xx, yy])
             fn = function([xx, yy], [dx, dy])
             xv = np.random.rand(16).astype(config.floatX)
@@ -180,13 +185,13 @@ class T_OpFromGraph(unittest_tools.InferShapeTester):
         du = T.vector()
         dv = T.Rop(y, x, du)
         fn = function([x, W, du], dv)
-        xval = numpy.random.rand(16).astype(config.floatX)
-        Wval = numpy.random.rand(16, 16).astype(config.floatX)
-        duval = numpy.random.rand(16).astype(config.floatX)
-        dvval = numpy.dot(duval, Wval)
+        xval = np.random.rand(16).astype(config.floatX)
+        Wval = np.random.rand(16, 16).astype(config.floatX)
+        duval = np.random.rand(16).astype(config.floatX)
+        dvval = np.dot(duval, Wval)
         dvval2 = fn(xval, Wval, duval)
         print(dvval, dvval2)
-        assert numpy.allclose(dvval2, dvval)
+        assert np.allclose(dvval2, dvval)
 
     @test_params
     def test_rop_override(self, cls_ofg):
@@ -197,18 +202,25 @@ class T_OpFromGraph(unittest_tools.InferShapeTester):
             u, v = epts
             return [u * y * 2. + x * v * 1.5]
 
+        u, v = T.vectors('uv')
+        op_mul_rop = cls_ofg([x, y, u, v], ro([x, y], [u, v]))
         op_mul = cls_ofg([x, y], [x * y], rop_overrides=ro)
-        xx, yy = T.vector('xx'), T.vector('yy')
-        zz = op_mul(xx, yy)
+        op_mul2 = cls_ofg([x, y], [x * y], rop_overrides=op_mul_rop)
 
+        # single override case
+        xx, yy = T.vector('xx'), T.vector('yy')
         du, dv = T.vector('du'), T.vector('dv')
+        for op in [op_mul, op_mul2]:
+            zz = op_mul(xx, yy)
             dw = T.Rop(zz, [xx, yy], [du, dv])
             fn = function([xx, yy, du, dv], dw)
-        vals = numpy.random.rand(4, 32).astype(config.floatX)
+            vals = np.random.rand(4, 32).astype(config.floatX)
             dwval = fn(*vals)
-        assert numpy.allclose(
+            assert np.allclose(
                 dwval, vals[0] * vals[3] * 1.5 + vals[1] * vals[2] * 2.)
 
+        # TODO list override case
+
     @test_params
     def test_nested(self, cls_ofg):
         x, y = T.vectors('xy')