Support scaler tensor

Author: zhiqiu

python/paddle/fluid/tests/unittests/test_var_base.py

@@ -466,6 +466,17 @@ def test_tensor_str3(self):
         self.assertEqual(a_str, expected)
         paddle.enable_static()
 
+    def test_tensor_str_scaler(self):
+        paddle.disable_static(paddle.CPUPlace())
+        a = paddle.to_tensor(np.array(False))
+        a_str = str(a)
+
+        expected = '''Tensor(shape=[], dtype=bool, place=CPUPlace, stop_gradient=True,
+       False)'''
+
+        self.assertEqual(a_str, expected)
+        paddle.enable_static()
+
 
 class TestVarBaseSetitem(unittest.TestCase):
     def setUp(self):

python/paddle/tensor/to_string.py

@@ -153,7 +153,7 @@ def _format_tensor(var, sumary, indent=0, max_width=0, signed=False):
     if len(var.shape) == 0:
         # currently, shape = [], i.e., scaler tensor is not supported.
         # If it is supported, it should be formatted like this.
-        return _format_item(var.item(0), max_width, signed)
+        return _format_item(var, max_width, signed)
     elif len(var.shape) == 1:
         if sumary and var.shape[0] > 2 * edgeitems:
             items = [