Chris Angelico wrote:
> On Tue, 11 Jul 2023 at 08:05, Jothir Adithyan adithyanjot...@gmail.com wrote:
> > Assumptions:
> > The problem statement is based on a few assumptions:
> >
> > You prefer chaining `get` statements for cleaner code.
> > You expect at least some of the `get` methods to return `None`.
> > You want to avoid the hassle of using `try` and `except` for every `get`
> > chain.
> >
> > The main assumption here is that None is a perfectly valid value in
> your data, and should be equivalent to the key being omitted. I think
> this is uncommon enough to be better done with custom code. But
> fortunately, there's a really cool way to write that custom code, and
> that's a path lookup - this is a sort of function that I've written in
> a lot of these situations. Using your examples:
> > import contextlib
> > parent_dict = PlayDict()
> > parent_dict['k1'] = None
> > parent_dict['k2'] = {"child_key": "val"} # Parent dict can contain nested
> > dicts
> > with contextlib.suppress(AttributeError):
> > result = parent_dict.get("k1", {}).get("child_key") # This will raise
> > AttributeError
> > result = parent_dict.get_or("k1", default={},
> > arbitrary={}).get("child_key") # This will work
> > I'd write it like this:
> def lookup(basis, *keys, default=None):
> for key in keys:
> basis = basis.get(key)
> if basis is None: return default
> return basis
> result = lookup(parent_dict, "k1", "child_key")
> This quite tidily expresses the intent ("delve into this dictionary
> and follow this path, returning None if there's nothing there"), and
> is compact, with no repetition. It's a relatively short helper
> function too, and easy to change into other forms. For example, here's
> another version that I use, which guarantees to always return a
> dictionary:
> def lookup(basis, *keys):
> for key in keys:
> if key not in basis: basis[key] = {}
> basis = basis[key]
> return basis
> Etcetera. Flexible and very handy.
> ChrisA
Hey Chris, thank you for your time and insight.
I've thought about this for some time, and I believe that adding this feature
could indeed be a useful and concise helper for many Python users, especially
for API integrations and web scraping where encountering None values is quite
common. Do you think it would be feasible to modify the existing get function
to include a new parameter or perhaps introduce a new function altogether?
I'm trying to understand why this idea may not be considered favorable. What
are the reasons for not having this feature? What makes the current approach
better than having this additional functionality?
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