为了支持多种操作系统的使用: 文件。写(f'some字符串和/或{variable}。{os.linesep}”)

我真的不想每次都输入\n， @matthause的答案似乎不适合我，所以我创建了自己的类

class File():

    def __init__(self, name, mode='w'):
        self.f = open(name, mode, buffering=1)
        
    def write(self, string, newline=True):
        if newline:
            self.f.write(string + '\n')
        else:
            self.f.write(string)

这就是它的实现

f = File('console.log')

f.write('This is on the first line')
f.write('This is on the second line', newline=False)
f.write('This is still on the second line')
f.write('This is on the third line')

这应该在日志文件中显示为

This is on the first line
This is on the second lineThis is still on the second line
This is on the third line

你可以在需要这种行为的特定地方装饰方法write:

#Changed behavior is localized to single place.
with open('test1.txt', 'w') as file:    
    def decorate_with_new_line(method):
        def decorated(text):
            method(f'{text}\n')
        return decorated
    file.write = decorate_with_new_line(file.write)
    
    file.write('This will be on line 1')
    file.write('This will be on line 2')
    file.write('This will be on line 3')

#Standard behavior is not affected. No class was modified.
with open('test2.txt', 'w') as file:
        
    file.write('This will be on line 1')
    file.write('This will be on line 1')
    file.write('This will be on line 1')  

除非写入二进制文件，否则使用打印。下面的例子很适合格式化csv文件:

def write_row(file_, *columns):
    print(*columns, sep='\t', end='\n', file=file_)

用法:

PHI = 45
with open('file.csv', 'a+') as f:
    write_row(f, 'header', 'phi:', PHI, 'serie no. 2')
    write_row(f)  # additional empty line
    write_row(f, data[0], data[1])

您还可以使用partial作为一种更python化的方式来创建这种包装器。在下面的例子中，用预定义的kwargs打印行。

from functools import partial


with open('file.csv', 'a+') as f:
    row = partial(print, sep='\t', end='\n', file=f)

    row('header', 'phi:', PHI, 'serie no. 2', end='\n\n')
    row(data[0], data[1])

注:

打印文档 “{},{}”。format(1， 'the_second') - https://pyformat.info/， PEP-3101 '\t' -制表符 函数定义中的*列-将任意数量的参数分派到列表-参见关于*args和**kwargs的问题

如果write是回调，则可能需要自定义writeln。

  def writeln(self, string):
        self.f.write(string + '\n')

本身在自定义打开器中。参见此问题的答案和反馈:在python 3中子类化文件对象(扩展打开和关闭操作)

(上下文管理器)

当我使用ftplib从“基于记录”(FB80)的文件中“检索行”时，我遇到了这个问题:

with open('somefile.rpt', 'w') as fp:
     ftp.retrlines('RETR USER.REPORT', fp.write)

最后得到一个没有换行符的长记录，这可能是ftplib的一个问题，但不清楚。

这就变成了:

with OpenX('somefile.rpt') as fp:
     ftp.retrlines('RETR USER.REPORT', fp.writeln) 

它起作用了。这是一些人正在寻找的用例。

完整的声明(只有最后两行是我的):

class OpenX:
    def __init__(self, filename):
        self.f = open(filename, 'w')

    def __enter__(self):
        return self.f

    def __exit__(self, exc_type, exc_value, traceback):
        self.f.close()

    def writeln(self, string):
        self.f.write(string + '\n')

你可以通过两种方式做到这一点:

f.write("text to write\n")

或者，取决于你的Python版本(2或3):

print >>f, "text to write"         # Python 2.x
print("text to write", file=f)     # Python 3.x