How to escape special characters (e.g., string.whitespace) in log messages? - python-3.x

Question

I'm trying to log strings with special characters in them. I know python has a logging module but for simplicity I've defined the following log function which takes a file handle and the message to be logged:
def log(logfp, msg):
logfp.write(f'{msg}\n')
fp = open('logfile.txt', 'w')
log(fp, 'Hello World!')
log(fp, 'World:\nHello, Bob!')
fp.close()
logfile.txt
Hello World!
World:
Hello, Bob!
What I would like is:
Hello World!
World:\nHello, Bob!
So that each line of the logfile corresponds exactly to a single call to log().
I tried using string.replace(r'\', r'\\') but that did not work:
def log(logfp, msg):
msg = msg.replace(r'\\', r'\\\\')
logfp.write(f'{msg}\n')
I tried Cid's suggestion which worked for \n but not other whitespace chars:
import os
import string
def log(fp, msg):
msg = msg.replace("\n", "\\n")
fp.write(f'{msg}\n')
# Replaces \t \n \r \x0b \x0c with a backslash counterpart (not including space chars)
def log2(fp, msg):
replacement = {ch:f'\\{ch}' for ch in string.whitespace[1:]}
for ch in string.whitespace[1:]:
msg = msg.replace(ch, replacement[ch])
fp.write(f'{msg}\n')
os.chdir(r'C:\Users\mtran\Desktop') # Change working directory
logfp = open('logfile.txt', 'w')
log(logfp, 'Hello World!')
log(logfp, 'World:\nHello, Bob!')
log2(logfp, 'World:\t\n\r\x0b\x0cHello, Everyone!')
logfp.close()
logfile.txt
Hello World!
World:\nHello, Bob!
World:\ \
\
\Hello, Everyone!

Answer 1

in the string "\n", you can't directly replace \ by \\ because \n is one character. You see it composed with \ and n but it's interpreted as one character.
You'd rather replace \n by \\n :
def log(msg):
msg = msg.replace("\n", "\\n")
print(msg)
log('Hello World!')
log('World:\nHello, Bob!')
This outputs
Hello World!
World:\nHello, Bob!