可选多行字符串替换

Question

我有一个带有一些占位符的长字符串，比如%name%，应该用dict给定的值来替换。根据this链接，我能够解决它。但是，如果另一个参数为True，则某些部分只应包含在返回的字符串中。例如，使用此格式：

>>optional:This should only get printed, if 'optional' is True<<

我可能会让它工作，但我无法创建一个同样适用于多行的正则表达式

import re 

# This works (https://stackoverflow.com/questions/26844742/advanced-string-replacements-in-python)
def replaceParameter(string, replacements):
  return re.sub('%(\w+)%', lambda m: replacements[m.group(1)], string)

# This does not work
def replaceOptionalText(myString, replacements):
  occurences = re.findall(">>(.*?):(.*)<<", myString, re.MULTILINE)
  # ... #

myLongString = r"""My name is %name%.
I want to >>eat:eat some %food%.
(in two lines)<<
>>drink:drink something<<
"""

replacements = {
  'name': 'John',
  'eat': True,
  'food': 'Apples',
  'drink': False,
}

myLongString = replaceOptionalText(myLongString, replacements)
myLongString = replaceParameter(myLongString, replacements)
print(myLongString)

根据预期产出：

My name is John.
I want to eat some Apples.
(in two lines)