爲什麼tf.Variable是可迭代的，但不能重複

Question

爲什麼這是真的：

from collections import Iterable 
import tensorflow as tf 

v = tf.Variable(1.0) 
print(isinstance(v, Iterable)) 

True 

而這

iter(v) 

給

TypeError: 'Variable' object is not iterable. 

Answer 1

我發現下面的方法Tensorflow的變量類：

def __iter__(self): 
    """Dummy method to prevent iteration. Do not call. 
    NOTE(mrry): If we register __getitem__ as an overloaded operator, 
    Python will valiantly attempt to iterate over the variable's Tensor from 0 
    to infinity. Declaring this method prevents this unintended behavior. 
    Raises: 
     TypeError: when invoked. 
    """ 
    raise TypeError("'Variable' object is not iterable.") 

https://github.com/tensorflow/tensorflow/blob/master/tensorflow/python/ops/variables.py#L366