OrderedDicts and tuples inside custom functions

[lucasbracher]

Good morning!

I don't know if I'm abusing the intended purpose of this project, but I created a function that recursively looks for a given key inside a JSON. The original code follows:

def key_exists(obj, key):
    stack = [obj]
    while stack:
        current = stack.pop()
        if isinstance(current, dict):
            if key in current:
                return True
            stack.extend(current.values())
        elif isinstance(current, list):
            stack.extend(current)
    return False

I tested it as a standalone function, and it worked like a charm.

However, I tested it as an embedded function in the context, and it didn't work. After some peeks and pokes, I discovered the JSON was transformed, it changed the dicts into OrderedDicts and lists into tuples. After some changes, the following code worked:

def key_exists(obj, key):
    stack = [obj]
    while stack:
        current = stack.pop()
        if isinstance(current, tuple):
            current = list(current)
        if isinstance(current, dict) or isinstance(current, OrderedDict):
            if key in current:
                return True
            stack.extend(list(current.values()))
        elif isinstance(current, list):
            stack.extend(current)
    return False

My question is, why exactly did it happen?

Thank you for the clarification!