创建空图层时，不会预先实例化Tensorflow变量

import tensorflow as tf

class CustomLayer(tf.keras.layers.Layer):
    def __init__(self, units=32, input_dim=32):
        super(CustomLayer, self).__init__()
        self.units = units
        self.kernel = None
        self.bias = None

    def build(self, input_shape):
        self.kernel = self.add_weight(shape=(input_shape[-1], self.units),
                                      initializer='random_normal',
                                      trainable=True)
        self.bias = self.add_weight(shape=(self.units,),
                                    initializer='zeros',
                                    trainable=True)

    def call(self, inputs):
        return tf.matmul(inputs, self.kernel) + self.bias

# 创建图层实例
layer = CustomLayer(units=64, input_dim=128)

# 手动初始化变量
layer.build(input_shape=(None, 128))

# 打印变量
print(layer.kernel)
print(layer.bias)