stasharrofi/pytyped

A set of Python packages to enable as much type-driven development as possible in Python, i.e., start with defining your type and let repetitive mundane tasks be automated.

pytyped's Issues

Bug in generic extractions

The following code enters an infinite loop in the extractor:

from dataclasses import dataclass
from typing import List, Generic, TypeVar

from pytyped.json.encoder import AutoJsonEncoder

T = TypeVar("T")


@dataclass
class A(Generic[T]):
    t: T


@dataclass
class B:
    x: int


@dataclass
class C(Generic[T]):
    l: List[A[T]]


a = AutoJsonEncoder()
a.extract(C[B])  # enters an infinite loop here

Class hierarchies as sum types

Currently, the only union types supported are Union[T1, T2, ...., Tn] that cannot be named. For example, it is not possible to distinguish Union[T1, Union[T2, T3]] from Union[Union[T1, T2], T3]. However, in most real-world scenarios, sum types are named and these names come in handy when tagging serialized sum types.

A prevalent example of named sum-types are class hierarchies.

For example, when decoding JSON, an unnamed union can be as unrestricted as a priority-based decoder but a named union has some structure to it such as being a JSON object and using the name of the super class as a field inside the JSON to show the type that is being decoded. In the absence of named unions, such a field would either have to have a very generic name (such as tag) or it would have to be manually generated.

So, three main asks:

1. Separate the concept of named unions from unnamed unions.
2. Implement class hierarchy auto extraction in extractor.
3. Implement both named and unnamed JSON decoding/encoding.

One additional ask:
Decoding/encoding JSON for named unions should allow both the following:

{
  "SuperClassName": "SubClassName",
  ...  // sub-class fields
}

and

{
  "type": "SubClassName",
  "value": sub_class_encoding
}

Improve README

There are positions marked as WIP. It can also benefit from more details and examples. In particular sum types, product types, generics, etc can all be defined more clearly.

Add unit tests

Missing required dependency `python-dateutil`

How to reproduce:

cd /tmp

# Creating a new venv
python3 -m venv foo
source foo/bin/activate
pip install --upgrade pip

# Install the lib
pip install pytyped

# Try to simply import it
python -c 'from pytyped.json.decoder import JsonDecoder, AutoJsonDecoder'
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/private/tmp/foo/lib/python3.8/site-packages/pytyped/json/decoder.py", line 8, in <module>
    from dateutil import parser
ModuleNotFoundError: No module named 'dateutil'

How to fix:

pip install python-dateutil

python -c 'from pytyped.json.decoder import JsonDecoder, AutoJsonDecoder'
# Works fine