Python中带括号和不带括号的调用方法 [英] Calling Method with and without Parentheses in Python

问题描述

我意识到有些方法应该用 () 调用，而其他方法则不能.如何使用 IPython 检查，例如是否使用括号?例如下面的文件 scratch.py​​

I've realized that some methods should be called with (), while others can't. How can I check, using IPython e.g., whether to use parentheses or not? For example the following file scratch.py

import numpy as np

arr = np.random.randn(5)

print arr.sort, "\n"
print arr.sort(), "\n";
print arr.shape, "\n";
print arr.shape(), "\n";

产生这个输出:

<built-in method sort of numpy.ndarray object at 0x7fb4b5312300> 

None 

(5,) 

Traceback (most recent call last):
  File "scratch.py", line 8, in <module>
    print arr.shape(), "\n";
TypeError: 'tuple' object is not callable

推荐答案

那些不是方法，那些是 属性.descriptor 由 Python 本身在幕后调用.

Those are not methods, those are properties. The descriptor is invoked behind the scenes by Python itself.

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