Content manager for joining strings. Similar to "join" function,

string_joiner.py

from contextlib import contextmanager
from typing import List, Any, Iterator


class StringJoiner(List[str]):
    def __init__(self, sep: str = " ", *args: str) -> None:
        super().__init__(*args)
        self.sep = sep


@contextmanager
def joiner(*args: Any) -> Iterator[StringJoiner]:
    string_list = StringJoiner(*args)
    try:
        yield string_list
    finally:
        string_list.result = f"{string_list.sep}".join(string_list)


# usage example        
with joiner(", ") as j:
    j.append("Hello World!!!")
    j.append("Happy Coding!!!")

print(j.result)
# Hello World!!!, Happy Coding!!!