update document template for unary elementwise layers (#25896)

1. update document template for unary elementwise layers(a.k.a. activation layer);
2. remove generate_op_noattr and use generate_activation instead; remove redundant function copies;
3. minor update for docstring to fix rst format errors.
4. fix doc for Rsqrt OP
5. add sample code for each activation separately;
6. remove the unused deprecated decorator.

paddle/fluid/operators/activation_op.cc

@@ -199,7 +199,7 @@ $$out = x - \\frac{e^{x} - e^{-x}}{e^{x} + e^{-x}}$$
 UNUSED constexpr char SqrtDoc[] = R"DOC(
 Sqrt Activation Operator.
 
-.. math:: out=\sqrt x=x^{1/2}
+.. math:: out=\\sqrt{x}=x^{1/2}
 
 **Note**:
   input value must be greater than or equal to zero.
@@ -211,7 +211,7 @@ Rsqrt Activation Operator.
 
 Please make sure input is legal in case of numeric errors.
 
-$$out = \frac{1}{\sqrt{x}}$$
+$$out = \\frac{1}{\\sqrt{x}}$$
 
 )DOC";
 

python/paddle/fluid/layers/layer_function_generator.py

@@ -25,8 +25,7 @@ from ..layer_helper import LayerHelper
 from ..data_feeder import check_variable_and_dtype
 
 __all__ = [
-    'deprecated', 'generate_layer_fn', 'generate_activation_fn', 'autodoc',
-    'templatedoc'
+    'generate_layer_fn', 'generate_activation_fn', 'autodoc', 'templatedoc'
 ]
 
 
@@ -82,8 +81,9 @@ def _generate_doc_string_(op_proto,
     buf.write(escape_math(op_proto.comment))
     buf.write('\nArgs:\n')
     for each_input in op_proto.inputs:
-        line_begin = '    {0}: '.format(_convert_(each_input.name))
+        line_begin = '    {0}'.format(_convert_(each_input.name))
         buf.write(line_begin)
+        buf.write(" (Tensor): ")
         buf.write(escape_math(each_input.comment))
         if each_input.duplicable:
             buf.write("  Duplicatable.")
@@ -125,6 +125,8 @@ def _generate_doc_string_(op_proto,
         for each_opt in op_proto.outputs:
             if not each_opt.intermediate:
                 break
+        buf.write(_convert_(each_opt.name))
+        buf.write(' (Tensor): ')
         buf.write(escape_math(each_opt.comment))
 
     return buf.getvalue()
@@ -275,50 +277,11 @@ def generate_activation_fn(op_type):
     func.__doc__ = _generate_doc_string_(
         op_proto,
         additional_args_lines=[
-            "name(str, optional): The default value is None.  Normally there is no need for user to set this property.  For more information, please refer to :ref:`api_guide_Name` ."
+            "name (str, optional): Name for the operation (optional, default is None). For more information, please refer to :ref:`api_guide_Name`."
         ])
-    func.__doc__ = func.__doc__ + """
-
-Return type
-  Variable
-
-Examples:
-    .. code-block:: python
-
-        import paddle
-        import numpy as np
-
-        paddle.enable_imperative()
-        x_data = np.array([1, 2, 3, 4]).astype(np.float32)
-        x = paddle.imperative.to_variable(x_data)
-        res = paddle.%s(x)
-        print(res.numpy())
-""" % op_type
     return func
 
 
-def deprecated(func_or_class):
-    """
-    Deprecated warning decorator. It will result a warning message.
-    Should be used before class or function, member function
-    """
-
-    @functools.wraps(func)
-    def func_wrapper(*args, **kwargs):
-        """
-        Wrap func with deprecated warning
-        """
-        warnings.simplefilter('always', DeprecationWarning)  # turn off filter
-        warnings.warn(
-            "Call to deprecated function {}.".format(func.__name__),
-            category=DeprecationWarning,
-            stacklevel=2)
-        warnings.simplefilter('default', DeprecationWarning)  # reset filter
-        return func(*args, **kwargs)
-
-    return func_wrapper
-
-
 def autodoc(comment=""):
     def __impl__(func):
         func.__doc__ = _generate_doc_string_(OpProtoHolder.instance(
@@ -384,3 +347,14 @@ def templatedoc(op_type=None):
         return func
 
     return __impl__
+
+
+def add_sample_code(func, sample_code):
+    """
+    Append sample code for dynamically generated functions. 
+
+    Args:
+       func: The function of the function to be append sample code to.
+       sample_code: sample code session in rst format.
+    """
+    func.__doc__ = func.__doc__ + sample_code

python/paddle/tensor/math.py

@@ -21,7 +21,7 @@ from ..fluid import layers
 from ..fluid.framework import core, _varbase_creator, in_dygraph_mode, Variable
 from ..fluid.layer_helper import LayerHelper
 from ..fluid.data_feeder import check_variable_and_dtype, check_type, check_dtype, convert_dtype
-from ..fluid.layers.layer_function_generator import _generate_doc_string_
+from ..fluid.layers.layer_function_generator import _generate_doc_string_, generate_activation_fn
 import sys
 
 # TODO: define math functions
@@ -59,6 +59,9 @@ from ..fluid.layers import square    #DEFINE_ALIAS
 from ..fluid.layers import stanh    #DEFINE_ALIAS
 from ..fluid.layers import atan    #DEFINE_ALIAS
 from ..fluid.layers import erf    #DEFINE_ALIAS
+from ..fluid.layers import sqrt    #DEFINE_ALIAS
+from ..fluid.layers import sin    #DEFINE_ALIAS
+from ..fluid.layers import tanh    #DEFINE_ALIAS
 
 from ..fluid.layers import increment    #DEFINE_ALIAS
 from ..fluid.layers import multiplex    #DEFINE_ALIAS
@@ -123,68 +126,8 @@ __all__ = [
         'trace',
         'kron'
 ]
-
-
 # yapf: enable.
 
-
-def generate_op_noattr(op_type):
-    """Register the Python layer for an Operator without Attribute..
-
-    Args:
-       op_type: The name of the operator to be created.
-
-    This function takes in the operator type (sin, tanh etc) and
-    creates the operator functionality.
-
-    """
-    op_proto = OpProtoHolder.instance().get_op_proto(op_type)
-
-    def func(x, name=None):
-        if in_dygraph_mode():
-            op = getattr(core.ops, op_type)
-            return op(x)
-
-        check_variable_and_dtype(x, 'x', ['float16', 'float32', 'float64'],
-                                 op_type)
-        helper = LayerHelper(op_type, **locals())
-
-        out = helper.create_variable_for_type_inference(dtype=x.dtype)
-        helper.append_op(type=op_type, inputs={"X": x}, outputs={"Out": out})
-        return out
-
-    func.__name__ = op_type
-    func.__doc__ = _generate_doc_string_(
-        op_proto,
-        additional_args_lines=[
-            "name(str, optional): The default value is None.  Normally there is no need for user to set this property.  For more information, please refer to :ref:`api_guide_Name`.\n    "
-            "out(Variable, optional): The default value is None. Optional output can be any created Variable that meets the requirements to store the result of operation. if out is None, a new Varibale will be create to store the result."
-        ])
-    func.__doc__ = func.__doc__ + """
-
-Return type
-  Variable
-Examples:
-    .. code-block:: python
-
-        import numpy as np
-
-        import paddle
-        import paddle.fluid as fluid
-
-        inputs = fluid.data(name="x", shape = [None, 4], dtype='float32')
-        output = paddle.%s(inputs)
-
-        exe = fluid.Executor(fluid.CPUPlace())
-        exe.run(fluid.default_startup_program())
-
-        #input.shape=1X4, batch_size=1
-        img = np.array([[1.0, 2.0, 3.0, 4.0]]).astype(np.float32)
-        res = exe.run(fluid.default_main_program(), feed={'x':img}, fetch_list=[output])
-        print(res)
-""" % op_type
-    return func
-
 @templatedoc()
 def pow(input, exponent, name=None):
     """
@@ -245,17 +188,6 @@ def pow(input, exponent, name=None):
     return out
 
 
-__ops__noattr__ = [
-    'atan',
-    'sin',
-    'sqrt',
-    'tanh',
-]
-
-for _OP in set(__ops__noattr__):
-    globals()[_OP] = generate_op_noattr(_OP)
-
-
 @dygraph_only
 def _elementwise_op_in_dygraph(x,
                                y,