Python - How to write recursively without global var

Question

I am working on a recursive function to write subcategories of a tree. I don't want to use a global var, what is the best way to write to the file on the recurse method?

def recurse(i):

    Xmlfile = file("index.html", "w")

    if i < 5:

        Xmlfile.write(str(i))

        recurse(i+1)

    return(None)



def main():

    Xmlfile = file("index.html", "w")

    Xmlfile.write("I")

    recurse(3)

    Xmlfile.write("O")

The expected output should be something along the lines of: I 3 4 5 O, but I am only getting I O.

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Answer 1

Pass it as an argument. The way you're doing it will reopen and truncate the file on every iteration.

def recurse(f, i):
    if i < 5:
        f.write(str(i))
        recurse(f, i+1)

def main():
    with open("index.html", "w") as xmlfile:
        xmlfile.write("I")
        recurse(Xmlfile, 3)
        xmlfile.write("O")

Note that I've replaced file() with the recommended open(), and have added a context manager to ensure the file gets closed.

Python - How to write recursively without global var

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