Because it saves me a lot of chars.

foo['name']['attr1']['attr2']['morefuckingattr'] vs foo.name.atr1.attr2.morefuckingattr

More of a personal preference.

That's a tough preference with Python, because of the semantics of what [] and . mean and how ingrained those semantics are in the language. Put another way, the following should hold:

       x.y == x.__getattr__("y")
    x["y"] == x.__getitem__("y")
    assignment == set{attr,item}
    del x.y, del x["y"], etc
    len() and slices of items, not attrs

etc, etc. If you start messing with those semantics, it can become very confusing very quickly in Python and you probably want a data type. Remember that Python gets nervous about cleverness.

One way I've approached your problem before is a recursive helper where I borrowed some concepts from jq:

    val = fetch(result_dict, "foo.bar.baz.plonk[0]")

Because then you can also isolate the missing key handling and all that stuff into your helper, rather than changing the semantics of an untyped dict. Aside from typing the responses from APIs -- the way better option -- I found this a reasonably Pythonic approach toward dealing with the annoyance.

Saving chars is often a poor reason to design a language feature.

Nope. It's called developer ergonomics.

The annoyance here is a feature not a bug. Deeply nested dictionaries, in my experience, are a source of infinite KeyErrors. The problem with using a dictionary as a cheap object is that it's very easy for it to be an object you weren't expecting. Don't nest dictionaries in Python!

So then what are you supposed to deserialize nested data structures like JSON into? Dictionaries are the obvious "right" way, Python's annoying tooling aside.

I'd say that dictionaries are only the obvious "right" way if you're not planning on accessing any of their fields. Otherwise you have some set of expected fields, in which case you can define a namedtuple and avoid a vast array of nasty surprises. It's really easy to initialize a namedtuple from a dict (use ), as long as the dict has the right fields. If it doesn't, and you're planning on using its fields, the fact that this raises an exception is a good thing.

What do you think of this library: https://github.com/selik/destructure

It'll enforce schema and destructure the nested dict/list that results from JSON decoding.

That's like asking, "What data structure should I use for this CSV file?"

Depends on the usage. Sometimes you leave them as nested dictionaries and lists. Sometimes you transform them into tabular data. Sometimes you aggregate, etc.

Namedtuples or classes that represent the data, I'd suggest personally.

I would agree. Namedtuple has an asdict method so that reserialization to JSON is simple; you can do the same for a class.

Developer ergonomics does not (always) mean "preventing effort".

If that were true, there would be no type systems.

Part of ergonomics is simplicity about what the thing you're looking at actually is.

No, it's called being terrible at your job. If you need to add complexity to your project just to save you some typing, you have no concept of what you're doing. It's like an accountant not understanding math.

Complexity can hide in unexpected places and sometimes a dash of complexity in one place can make something in another place much simpler.

I think this library has it's uses. I wouldn't use it uncritically but I wouldn't dismiss it either.

True, but it saves a relatively small number of chars (~12) and does so at the same time as:

A) Giving off a signal that you're dealing with an object rather than a dict.

B) Making it cumbersome to swap out some of those selectors with variables.

C) Making it difficult to deal with the attribute not being there (with a dict you can say .get("attr2", {}) and it returns a default.

I understand. I have another motivation which is getting JSON and wanting a OOP object to mainpluate with. Take AWS' boto3 response. Well documented but the nested response structure gives me a chill and I wish there's a direct object out of the JSON. I instead had to write my own class for the conversion. If I could mainpluate dict like mainpluatig attribute in a class then I could just write my function's contract "input is a response object from X APi" instead of "dict of this form."

Quite annoying and I know some people considered what I wish is a bad practice.

Personally, I only use hard-coded strings like that for shallow nesting. If I need to index 4 layers deep, something down there is going to be turned into an object, otherwise enumerating all the possible keys to ensure the code is correct becomes a nightmare. And once you do that, you can use dot notation anyway.

because of duck typing.

a['b'] = 'c' # means i must use a dict a.b = 'c' # means must be an obj

if they were interchangeable then I could have more reusable code.