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')  

如果你大量使用它(写了很多行)，你可以子类化'file':

class cfile(file):
    #subclass file to have a more convienient use of writeline
    def __init__(self, name, mode = 'r'):
        self = file.__init__(self, name, mode)

    def wl(self, string):
        self.writelines(string + '\n')

现在它提供了一个额外的函数wl来做你想要的:

with cfile('filename.txt', 'w') as fid:
    fid.wl('appends newline charachter')
    fid.wl('is written on a new line')

也许我遗漏了一些东西，比如不同的换行符(\n， \r，…)，或者最后一行也以换行符结束，但这对我来说是有效的。

好的，这里有一个安全的方法。

with open('example.txt', 'w') as f:
 for i in range(10):
  f.write(str(i+1))
  f.write('\n')

这将在新行中对每个数字写入1到10。

你可以使用:

file.write(your_string + '\n')

file_path = "/path/to/yourfile.txt"
with open(file_path, 'a') as file:
    file.write("This will be added to the next line\n")

or

log_file = open('log.txt', 'a')
log_file.write("This will be added to the next line\n")

你可以使用c风格的字符串格式化:

file.write("%s\n" % "myString")

更多关于字符串格式。