Created by: Annnnnnnnnnnnn

简单的代码如下：

encIdx = fluid.layers.data(name='encIdx', shape=[1], dtype='float32')
    temp = fluid.layers.fill_constant([1], dtype='float32', value=2.)
    cond = fluid.layers.equal(encIdx, temp)
    branch_1st = fluid.layers.IfElse(cond)
    with branch_1st.true_block():
        words_a = branch_1st.input(encIdx)
        words_b = fluid.layers.exp(words_a)
        fluid.layers.Print(words_b)
        branch_1st.output(words_a, words_b)

    with branch_1st.false_block():
        cond = fluid.layers.equal(encIdx, temp)
        branch_2nd = fluid.layers.IfElse(cond)
        with branch_2nd.true_block():
            words_a = branch_2nd.input(encIdx)
            words_b = fluid.layers.sqrt(words_a)
            fluid.layers.Print(words_b)
            branch_2nd.output(words_a, words_b)

        with branch_2nd.false_block():
            words_a = branch_2nd.input(encIdx)
            words_b = fluid.layers.square(words_a)
            fluid.layers.Print(words_b)
            branch_2nd.output(words_a, words_b)

        words_a, words_b = branch_2nd()
        branch_1st.output(words_a, words_b)

    a, b = branch_1st()
    place = fluid.CPUPlace()
    exe = fluid.Executor(place)
    exe.run(fluid.default_startup_program())
    a_, b_ = exe.run(fluid.default_main_program(),
                    feed={"encIdx": np.array([2.]).astype(np.float32)},
                    fetch_list=[a.name, b.name])
    print a_, a_.shape
    print b_, b_.shape

结果如下， 第二个ifelse块里的false也被执行了，而且结果也多不上。 1558618182 Tensor[exp_0.tmp_0] shape: [1,] dtype: f data: 7.38906,

1558618182 Tensor[sqrt_0.tmp_0] shape: [1,] dtype: f data: 1.41421,

[ 2. 0.] (2,) [ 7.38905621 0. ] (2,)