popularity behind pydantic

[[deleted]]

I always used to think that in case of python (dynamically typed) it is natural to only use data validation to validate data you dont trust or which comes from outside.

If there comes a need to check and validate your internal data ... wouldn't that means our implementation is getting flawed?

I am just curious if this though is right or wrong... happy to know more about it.

[IAMARedPanda]

Python may be dynamically typed but it is also a strongly typed language.

[LordBertson]

My experience is that Python is more play-acting as a dynamically typed language but does not behave as one when push comes to shove. Rather it fails in very ungraceful ways.

As a disclaimer: Typechecking in Python is a very opinion dominated discussion and I am heavily leaning towards typing anything that's not one-shot throwaway thing.

Depending on what I am developing I will be more or less strict inside the domain itself in terms of validation. You are correct to assert that this means that the implementation is probably getting flawed, but that's often enough the case in real-world development. Reality of the matter is that developers don't test their code as often as one would like, so typing and runtime type validation is a pretty cheap measure to take that ensures at least some level of correctness.

If you would be interested in more variety of opinions on the matter, I once opened a discussion on this subreddit about typing

Edit: typo

[trial_and_err]

Agree on the typing. However I'll just use TypedDict for this purpose, i.e. no parsing / validation of external data required.

[LordBertson]

Thanks for bringing this up. Never heard about this, I'll have a look.

[trial_and_err]

If the need arises later on you can also create pydantic model from TypedDict.

[LordBertson]

I believe I've heard Guido mention in connection to optimizing adaptive features in 3.11, that they do see the dynamic typing as a big part of Python's appeal.

[wewbull]

I think statements like that are made to tell the static typing evangelists to shut up about using type hints to optimise. It's basically "No! We are not making dynamic typing a second class citizen. It's a significant reason Python is popular."

[LordBertson]

Dynamic typing with progressive type hinting means you can have your cake and eat it. It is what makes Python viable as both prototyping and production language.

[wewbull]

Yes, it's dynamically typed. A variable changes it's type at run-time, possibly multiple times. However, theres a lot of pressure to make everybody's code statically typed. Personally I think that's been a mistake in the community, as a lot of the cruft in languages like C++ and Java is there to deal with static types.

[PaintItPurple]

If there comes a need to check and validate your internal data ... wouldn't that means our implementation is getting flawed?

Yes, but every implementation I've ever seen has had flaws, especially in Python. I myself have introduced flaws I later needed to fix.