提交 dde0a280 编写于 作者: Q qiaolongfei

add doc for Switch

上级 e72eb0ed
......@@ -1132,6 +1132,28 @@ class ConditionalBlock(object):
class Switch(object):
"""
**Switch Class**
Many programming languages provide `switch` as a generalization of `if-elif-else`.
Switch class works just like a `if-elif-else`.
The Semantics:
1. A `switch` control-flow checks cases one-by-one.
1. The condition of each case is a boolean value, which is a scalar.
1. It runs the first matched case, or the default case if there is one.
1. Once it matches a case, it runs the corresponding branch and only that branch.
Examples:
.. code-block:: python
with control_flow.Switch() as switch:
with switch.case(global_step == zero_var):
tensor.assign(input=one_var, output=div_res)
"""
def __init__(self, name=None):
self.helper = LayerHelper('switch', name=name)
self.inside_scope = False
......@@ -1161,7 +1183,8 @@ class Switch(object):
return ConditionalBlockGuard(cond_block)
def default(self):
"""create a default case for this switch
"""
create a default case for this switch
"""
pre_cond_num = len(self.pre_not_conditions)
if pre_cond_num == 0:
......
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