Python，如何将输出发送到文件和终端

Question

我想使用 Python 将输出发送到终端上的文件 log.txt 和 STDOUT。这是我所拥有的:

import sys
class Logger(object):
    def __init__(self, filename="Default.log"):
        self.terminal = sys.stdout
        self.log = open(filename, "a")

    def write(self, message):
        self.terminal.write(message)
        self.log.write(message)

sys.stdout = Logger("log.txt")
print "Hello world !"            #This line is saved in log.txt and STDOUT

此程序将输出发送到文件和标准输出。我的问题是:文件的写入函数是如何被调用的？

Answer 1

来自documentation对于 sys.stdout:

stdout and stderr needn’t be built-in file objects: any object is acceptable as long as it has a write() method that takes a string argument.