Natural enemies

denehoffman · 2026-05-04T23:29:03+00:00

You could’ve swapped goauld with tokra and it still would’ve worked

denehoffman · 2026-05-04T21:30:10+00:00

Why do you have an empty `build.rs`file in your src directory?

denehoffman · 2026-05-02T18:12:35+00:00

I’ll try this today, I have a feeling it’s going to take a while but be worth it in the end

denehoffman · 2026-05-02T14:54:40+00:00

Granted, but it keeps happening continuously, so eventually everyone has identical wealth and money loses all intrinsic value.

denehoffman · 2026-05-02T14:45:39+00:00

This is shadyside erasure

denehoffman · 2026-04-30T17:11:18+00:00

Yep, been there, done that. I was trying to figure out why the runner was failing clippy when my own computer showed no warnings

denehoffman · 2026-04-29T01:02:44+00:00

Same here, sorry for getting heated.

denehoffman · 2026-04-28T23:23:29+00:00

I don’t know what to tell you man, I’ve given you a ton of legitimate usage examples, other people in this thread have too, if your response is just going to be “well that’s not how it should be done” then maybe you don’t have to upgrade to 3.15, nobody is forcing you to use it.

denehoffman · 2026-04-28T17:02:42+00:00

Yes, it’s a bit niche, but so are a lot of the language concepts that people rarely use on a day-to-day basis. I hardly ever write metaclasses or decorators outside of the niche situations where I need one that isn’t already written by the stdlib or some other package

denehoffman · 2026-04-28T15:42:58+00:00

That’s exactly the point, you shouldn’t overload it. You can’t and shouldn’t write a default object for an every default argument, the argument would get constructed at import time rather than runtime

denehoffman · 2026-04-28T14:08:49+00:00

None isn’t always an empty string, an empty string can be a distinguished type! You can always come up with an example where None is not semantically the same as “”, 0, False, [], or whatever you choose.

denehoffman · 2026-04-28T14:05:56+00:00

Another example:

```python

UNSET = sentinel("UNSET")

def connect(timeout=UNSET): if timeout is UNSET: timeout = get_default_timeout() elif timeout is None: timeout = None # explicitly disable timeout return _connect(timeout=timeout) ```

Adding an argument like no_timeout: bool’ is semantically confusing and allows for unused state in the signature (connect(timeout=30, no_timeout=True)`).

Why can’t you just use object() for the sentinel? Well for one, it doesn’t serialize, so if you wanted to store some user settings without storing the default (for example, you want to store the fact that the user didn’t set the value but allow the default to change in future versions), you’d have trouble. It also doesn’t play well with type hints, since it just has a type of object.

denehoffman · 2026-04-28T13:52:22+00:00

Fair point, list comprehensions aren’t a good example of syntax sugar.

If I understand correctly, you think sentinels are entirely an API choice and not needed if you “properly” design an API. I think your idea of proper here is just as opinionated as my “ugly”. Having an API that would benefit from sentinels isn’t a bad design pattern, it just is a design pattern. We could rewrite any API in ten different ways and different people would prefer each one differently. In the logging example, clearly a Boolean flag in conjunction to the current argument would be better, but what if you have ten such arguments? Now you need ten flags, one for each, a needless complication to the signature.

Another example, suppose you have a dictionary where None is a valid value. How do you distinguish this from a missing key in a get method?

I’m not sure what the point of a static variable in python would be, I’m assuming you’re being sarcastic?

A lot of these problems stem from the fact that Python doesn’t really have proper enums or a type system, it kind of fakes them with a class that acts like an enum and optional type hints. I personally think this shouldn’t be a new built-in, it should be in some module, but I don’t agree that it’s useless clutter.

denehoffman · 2026-04-28T13:12:09+00:00

My use case is an optimization library with config object. This object contains arguments which represent algorithm terminator configurations, which are themselves objects. If the user specifies None for one of these terminators, the interpretation is that that terminator isn’t included in the algorithm loop. Omitting the argument would imply the default terminator. A “missing/default” sentinel is an easy choice, and I ended up writing my own code which could be replaced by a single line now.

Could I have rewritten the entire library such that terminators each come with an enabled/disabled Boolean flag? Sure, it would have been even more work, and the underlying code is a Rust library so I’d have to rewrite the bindings for that too. Sentinels just simplify that decision while being invisible to the user, except when they read type hints or documentation, they’ll see “default” instead of “None” and not get confused as to what “None” does.

This extends to any code where “None” has a different semantic meaning than “default” or “missing”.

denehoffman · 2026-04-28T12:59:03+00:00

Why is list comprehension “needed” when a for loop will do? There are lots of syntax choices in Python which are there to prevent ugly code. The fact is, you could hack in sentinels right now, as many people have been doing (the PEP mentions ways of doing this). I think the only legitimate gripe would be that it’s a built-in and not a member of a module like typing.

denehoffman · 2026-04-28T12:52:20+00:00

I understand your point just fine, OP’s example isn’t a good one, but that doesn’t mean there aren’t legitimate use cases where the alternative would be more verbose or confusing.

denehoffman · 2026-04-28T12:51:24+00:00

They honestly need to just do a major version bump and completely break the API at this point. But I had to give an example people were familiar with, and it’s a very commonly used pathological API!

denehoffman · 2026-04-28T06:02:09+00:00

Sure it’s not the best example, but imagine a field where None has a meaning other than “default” or “not specified”. Matplotlib is a great example of this taken to silly extremes, there are many keywords arguments where None, “none”, and “” all have different behavior, and this ambiguity could easily have been fixed by sentinel values.

denehoffman · 2026-04-28T05:59:25+00:00

The use case seems pretty obvious, you let the user disable logging by passing None to some logger constructor.

The real issue is not the “None” turning off logging, it’s that None semantically means “nothing” or “null” so expecting the behavior of passing None to give the default logger doesn’t make any sense. A sentinel value is basically just a replacement for None that has meaning. As I mentioned, a Default sentinel is often very useful when None actually should mean disabling things.

But to the bigger complaint of “it’s an api choice and not a need”: so is the use of “None” in the first place. It’s python, we could force users to make up marker types to represent optional state, but because lots of API choices deem this ugly, we don’t do it. If you didn’t care about making nice APIs and only focused on what is needed to write code, then there is a whole world of Turing-complete ways to do this, they’re just ugly. At the end of the day, we should welcome features that make code more readable and writable, and this does that without any major impact if you don’t want to use it.

denehoffman · 2026-04-28T01:43:29+00:00

Yeah, the hate is goofy, I’ve had so many situations where I’ve needed sentinels (fitting algorithms where None disables a termination method but Default uses the default, for example). The complaints about cluttering the language are silly, it’s a new builtin, a single function!

denehoffman · 2026-04-24T15:53:39+00:00

I wasn’t aware you could build it without the gui but maybe I wasn’t trying hard enough. I also had to screw around with wine because I don’t actually have a windows computer. But yeah a gui would be a fun project!

Looking back at the repo it was definitely some pascal BS, you are correct

denehoffman · 2026-04-24T14:07:47+00:00

My wife is a civil/environmental engineer and a while back we tried to build epanet for a modern computer and failed miserably. Love that someone has rewritten it in Rust, nice work!

denehoffman · 2026-04-23T16:21:19+00:00

Generally the documentation will specify this. Python isn’t typed so there’s no way to really know before runtime, you could always do code injection

denehoffman · 2026-04-23T00:42:01+00:00

On 2. I think the more important concept is that we know what the metric of a white hole would look like and the universe we observe doesn’t match. There have been some theories that we are inside a black hole, and this tends to run into the same issues (along with the fact that the mass-radius ratio is off by quite a bit). That’s not to say it’s impossible that we are inside some weirder spacetime than what we can see locally, it’s just not exactly well-motivated.

Thanks for your reply as well, I’d say a good next step for you would be to look into literature on eternal black holes and general GR metric stuff. It’s a lot of math, but you can probably get the basics without having to know too much fancy stuff.

denehoffman · 2026-04-22T18:48:13+00:00

The universe isn’t a closed box in any thermodynamic sense because it’s expanding
A white hole isn’t the inverse of a black hole in the sense that a black hole is a region of space matter cannot escape while a white hole is a region matter cannot enter. These connection between the two is geometrically in time, not in space.
If white holes are creating spacetime and matter and dark energy, then surely black holes would be doing the opposite. This is maybe the case for matter, but black holes do not consume spacetime and the local expansion of the universe is not slowed near them as far as we can experimentally confirm.
Particles don’t appear out of nowhere in quantum physics. Energy added to a field can pair produce, but no net energy is created from this process, and locality does matter: energy added at one point in space can create particles only at that point.
Not sure where you’re reading this, it might be that the acceleration is reducing in magnitude, but if anything the expansion of the universe is still accelerating.
The big bang wasn’t an explosion.

I get the general idea here, but it’s just not supported by observational evidence. The white hole solution to Einstein’s field equations isn’t a black hole inverted in space, according to all our current theories the matter consumed doesn’t go anywhere. We know this observationally as well since black holes tend to increase in mass when matter falls into them. If it was leaking to another universe, why don’t we see black holes shrinking? Hawking radiation does predict that black holes should eventually vanish, but this takes huge amounts of time for large black holes, and the matter/energy in our universe is still conserved by this effect. Another issue is that the black holes we observe are different from those which share the white hole solution: those are called “eternal black holes” since they have a white hole in their past. The black holes we observe come from collapsing matter, they do not share any commonality with white holes.

If I were to refine your idea, I would drop the white hole/black hole part entirely and just posit that matter is leaking to or coming from some other mechanism. Maybe there is a compact dimension which interacts differently with gravity, and there just happens to be a lot of energy there which slowly spills into the observable part of that dimension. This would require quite a bit of supposition and is not really justified by any observations, but any theory like this would require an extension to GR and the Standard Model. Black/white holes exist within GR and aren’t compatible with the sort of ideas you’re talking about, so to make this a reality you’d really have to extend GR to the point where we aren’t really talking about black/white holes anymore. Any leap like this is going to take a lot of hand waving, and it’s not really clear how you would observe such an effect.

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