DotDict: A simple Python library to make chained attributes possible

https://github.com/nick-at-dave/DotDict

by astrea • 3 years ago

44 53 3 years ago

github.com

i13e• 3 years ago

Good video on this subject: https://www.youtube.com/watch?v=nDd2WVb_Enw

b33j0r• 3 years ago

Anthony’s video 100%.

For anyone who doesn’t watch… the point being made is that this has been done so many times that yet another implementation was pulled from the stdlib in 3.12 (AttrDict).

It’s true. I’ve implemented this several times myself, and thought it was a new/good idea every time until I remembered how many abstractions it breaks if I use it anywhere.

I can’t promise I won’t do it again in a few weeks! `NaturalDictLite` is probably coming around in the accompanying rotation of bad name ideas :p

dancenow• 3 years ago

This is the way. And that pip command is just clean.

Toxygene• 3 years ago

Have I lost my marbles? It doesn't work?

    (temp5)   ~/temp5 pip install .            
    ERROR: Directory '.' is not installable. Neither 'setup.py' nor 'pyproject.toml' found.

Izkata3• 3 years ago

Run it from a clone of the repo to install it to the system / your user.

I don't see a name to install this from pypi (I see several dotdict libraries on there but they don't link here, so don't know if this is there somewhere).

kshay• 3 years ago

So basically Perl autovivification for Python?

sekia• 3 years ago

Seems a subset of it. Practicality aside, Perl can autovivify not only hashes but also arrays:

  my %x;
  $x{foo}[1]{bar} = 42;  # %x is ( foo => [ undef, { bar => 42 } ] )

astrea4• 3 years ago

This is more of a political statement than a proper library. More to demonstrate the flexibility of Python given I was able to so easily do this.

nicwolff• 3 years ago

Could have been even easier: `argparse.Namespace` already has `__contains__()` ツ

That said, https://pypi.org/project/addict/ has been around a long time...

astrea4• 3 years ago

That contains doesn’t permit the behavior, though. It would give you an AttributeError if you attempted this.

Yes, addict seems to be exactly what I was going for.

Waterluvian2• 3 years ago

I enjoy how much complete control Python enables. It’s fun to turn it into what resembles a different language.

I want to make a library where you never ever call functions with fn() notation. But just utilize accessors and absolutely bastardize dicts.

richbell2• 3 years ago

My favorite example of this: https://old.reddit.com/r/learnprogramming/comments/kegalv/my...

gorgoiler• 3 years ago

Does it lazy-create leaf dicts on access? It would be preferable if they were only created on assignment, and failed if it’s just a get.

For example, if I call config.usors.adminn.naem I’d like it to fail loud and fast to point out the typos.

Izkata3• 3 years ago

Code looks like it's on access, but I didn't test it.

kzrdude• 3 years ago

I don't think it's possible in Python to detect the difference between access or write (when it's nested attributes).

heisenzombie• 3 years ago

Yeah it does. If you do:

    x = dd()
    print(x.tyypo.a.b)

you'll get "DotDict()"

The problem is that an object can't know whether you're getting a node that you're later going to assign a leaf to... or whether you're getting the node because you want to get the node.

   x = dd()
   x.a.b.c = "Foo"

is equivalent to:

   x = dd()
   y = x.a.b
   y.c = "Foo"

So "x.a.b" can't raise an exception.

Now, it's python, so you can do unholy things to make pretty much anything work. But I think it would be ugly.

samwillis• 3 years ago

They could add a __bool__ method to the class the returns false when that level of the namespace is empty. That would allow:

   if a.b.c:
       print("c:", a.b.c)

sidmitra2• 3 years ago

In case anyone is looking for mature alternatives that are used in production

https://pypi.org/project/python-box/

https://pypi.org/project/munch/

Halvedat• 3 years ago

Neither of these appear to have the chained attribute feature, from my surface level parse.

nmalaguti2• 3 years ago

Box can do it with

https://github.com/cdgriffith/Box/wiki/Types-of-Boxes#defaul...

sidmitra2• 3 years ago

It's there on the readme/pypi home for both; unless i'm misunderstanding what you mean by "chained"

    from box import Box
    movie_box = Box({ "Robin Hood: Men in Tights": { "imdb stars": 6.7, "length": 104 } })
    movie_box.Robin_Hood_Men_in_Tights.imdb_stars


    from munch import Munch
    b = Munch()
    b.hello = 'world'
    b.foo = Munch(lol=True)
    b.foo.lol

jperras• 3 years ago

python-box does this in the most intuitive way possible:

    >>> from box import Box
    >>> empty_box = Box(default_box=True)
    >>> empty_box.a.b.c.d.e.f.g # <Box: {}>

make3• 3 years ago

Munch is an unfortunate name

KolenCh• 3 years ago

How does these compare to glom?

https://glom.readthedocs.io

nathants• 3 years ago

this is cool!

i use a lot of defaultdict trees[1], and convert nested dicts to/from flat dicts with dots in their keys[2].

never underestimate the mighty dict.

1. https://github.com/nathants/py-util/blob/6844917fb51e9d24de1...

2. https://github.com/nathants/py-util/blob/6844917fb51e9d24de1...

bbstats• 3 years ago

I...do not prefer this syntax.

hk13372• 3 years ago

edict() is an interesting name for a dictionary function.

astrea4• 3 years ago

It’s a class instantiation with no arguments

hk13372• 3 years ago

Yeah, I was referring to the name choice. Edict being “A decree or proclamation issued by an authority and having the force of law.”

nmalaguti2• 3 years ago

This seems similar to the functionality exposed by Box.

https://github.com/cdgriffith/Box/wiki/Types-of-Boxes#defaul...

claytonjy2• 3 years ago

My general rule is, if I have a dict with a fixed set of keys, it should be a dataclass. Problem solved!

Then if I need to send or receive it, it's an easy conversion to a Pydantic BaseModel.

smashed• 3 years ago

And the dataclass serves as documentation for the available attributes and type safety..

It's really the way to go, takes a minute or two to define and saves so much headaches in the long run.

behnamoh• 3 years ago

Can dataclasses be serialized just as easily?

paulddraper• 3 years ago

Yes via pickle.

Or for JSON, dataclasses_json

jammycrisp• 3 years ago

Yep! Both msgspec (https://jcristharif.com/msgspec/supported-types.html#datacla...) and orjson support encoding dataclasses to JSON natively.

jwestbury• 3 years ago

In addition to the already-mentioned suggestions, you can also use marshmallow schemas to serialise complex objects, and there's even a package to autogen marshmallow schemas from dataclasses: https://pypi.org/project/marshmallow-dataclass/

rivepica• 3 years ago

100%. I don’t understand the obsession with bending dicts into something they are inherently bad at when actual alternatives in dataclasses and Pydantic models right there.

stavros• 3 years ago

I also created an alternative to this, a while back:

https://pypi.org/project/jsane/

Its syntax is a bit uglier, though.

bee_rider2• 3 years ago

If I do

config = dd()

config.users.foo = 'bar' config.users = ‘baz’

Is config.users turned into a string and config.users.foo is lost? Or is the equal symbol mapped to something cleverer than assignment?

fatso784• 3 years ago

This is a pretty cool idea. One comment —the print representation should be entirely akin to a dict, just braces. No DotDict wrapper. That’d be cool.

stuaxo• 3 years ago

Oh, I thought this was going to be like ChainMap, but for attributes, I'll stick with the one ChatGPT started for me.

barelysapient• 3 years ago

Why not use Pydantic or Dataclasses instead?

At least with Pydantic, there's the discipline to define the model and validation that a model instance is probably correct.

tniemi• 3 years ago

Here's my personal finger exercise: https://pypi.org/project/talamus-relatable/

It allows references to another data structures.

DotDict: A simple Python library to make chained attributes possible

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