Question

简单的问题，我想在我调用的每个print的前面附加文字，例如，如果我将文字设置为hello并运行它：

print 'hello there'
print ' hi again'

它会打印出来：

hellohello there
hello hi again

有没有办法这样做，而不使用函数来代替print？

Answer 1

您可以按照DevPlayer's post here on StackOverflow覆盖打印，稍作修改：

from __future__ import print_function
# Note: If you are using Python 3 leave this line out
# This must be the first statement before other statements.
# You may only put a quoted or triple quoted string, 
# Python comments or blank lines before the __future__ line.
import sys

def print(*args, **kwargs):
    """My custom print() function."""
    # Adding new arguments to the print function signature 
    # is probably a bad idea.
    # Instead consider testing if custom argument keywords
    # are present in kwargs
    sys.stdout.write('hello')
    return __builtins__.print(*args, **kwargs)

print ("hello there")
print (" hi again")

[编辑] ...或者正如DSM建议的那样，你可以避免使用sys调用：

from __future__ import print_function
# Note: If you are using Python 3 leave this line out
# This must be the first statement before other statements.
# You may only put a quoted or triple quoted string, 
# Python comments or blank lines before the __future__ line.

def print(*args, **kwargs):
    """My custom print() function."""
    # Adding new arguments to the print function signature 
    # is probably a bad idea.
    # Instead consider testing if custom argument keywords
    # are present in kwargs
    __builtins__.print('hello',end='')
    return __builtins__.print(*args, **kwargs)

print ("hello there")
print (" hi again")

Answer 2

您无法更改Python 2的print语句，但您可以编写自己的类文件对象并使用它：

class PrefixedFile(object):
    def __init__(self, f, prefix):
        self.f = f
        self.prefix = prefix

    def write(self, s):
        s = s.replace("\n", "\n"+self.prefix)
        self.f.write(s)

sys.stdout = PrefixedFile(sys.stdout, "hello: ")

print "One"
print "Two"

请注意，此代码不能正常工作，因为它在第一行缺少前缀，并在最后添加一个前缀，但您明白了！：）

Answer 3

尽管Jon Cage的回答是替换print()函数的好方法，但我建议使用自己的打印函数（使用Jon的代码）：

from __future__ import print_function
# Note: If you are using Python 3 leave this line out
# This must be the first statement before other statements.
# You may only put a quoted or triple quoted string, 
# Python comments or blank lines before the __future__ line.

def my_print(*args, **kwargs):
    """My custom print() function."""
    # Adding new arguments to the print function signature 
    # is probably a bad idea.
    # Instead consider testing if custom argument keywords
    # are present in kwargs
    print('hello', end='')
    print(*args, **kwargs)

与Jon的答案唯一的区别是你不会覆盖内置的 print()（“猴子修补”）。我提倡这样做而不是修改print()，因为这会使您的代码更易于维护，因为每个人都希望print()成为内置代码。

在print()中使用print 功能代替my_print()语句，提供greater flexibility。

附加到每条打印的邮件

3 个答案: