theg5prank
Joined 13 years ago
Joined 13 years ago
Whether an app containing code for 3 architectures qualifies as "true 5-arch universal" is in the eye of the beholder I guess.
I made no such claim. I said (in my opinion) C++ doesn't have the issue you're raising with Python because it has a completely different design that doesn't attempt to solve diamond problems in superclass attribute lookup. Are we not in agreement?
> I "brought it up" to illustrate it does one particular thing better than Python. Not to claim it does everything better than Python. If you want a simple, beginner-friendly language, avoid C++ like the plague.
You can validly think that C++'s choice here is better. I don't think there's a counterargument to personal preference here. My point was that it does not solve all of the problems Python's super builtin is designed to. And that's fine! It avoids the issue in question! I actually don't understand what you are arguing with here. Personally I think the design goals here are just so wildly different that I don't have a preference, but I admit that's kind of a cop-out.
> Idk, for starters maybe produce a warning when multiple inheritance occurs and one of the __init__s in the hierarchy doesn't call super().__init__.
In general I think having more "warning labels" on multiple inheritance is the right idea, if a language is going to persist in offering it at all. I think this would be a good start, especially for a linter.
What's your point about this nonstandard extension? My point is that C++ doesn't have the problem of classes not written to be part of a multiple inheritance hierarchy delegating somewhere unexpected because, by design, it doesn't attempt to solve the same problems that Python is. If anything that this nonstandard extension doesn't work in multiple inheritance is agreeing with the points I'm making.
> There's a lot more I could say about this (frankly the issue I outlined just scratch the surface of a deeper problem in Python), but this is diverting the discussion. Nobody even said C++ is simple or somehow easier to learn than Python in the first place; I was just pointing out an insidious issue in Python,
You were the one who brought up C++! (EDIT: this was in a cousin comment.) My point is that different languages navigate this thorny landscape in different ways, but the way in which Python does isn't as haphazard as you are suggesting.
> Exercise for the reader: suggest improvements
Perhaps being part of a multiple inheritance hierarchy is sharp and uncommon enough that it should be opt-in. What are yours?
Anyway, your argument seems to be that you should be able to use naively written classes in a multiple inheritance hierarchy. I suppose that's a defensible opinion, but it's also not the case in any language I know of; C++ solves the problem of not calling the "correct" superclass by default by foisting the responsibility of choosing the correct subset onto the derived class author, but doesn't solve the "I called my superclass' method too many times" problem, only the "I have too many (n>1) copies of my superclass' data" problem (the solution to which is also opt-in). Python resolves all three of these, but in so doing requires careful construction of multiple inheritance hierarchies and use of the super builtin that is religious to the point of fanatical. That's a tradeoff made in respect to a feature that, IMO, is inherently sharp.
Aside: "idiosyncratic" is an interesting word to use given that the C3 MRO was originally intended for Dylan.
Note that `object` being the root of the class hierarchy implies that you must have careful coordination between all classes in a multiple inheritance hierarchy to determine, for a particular method, when subclasses may/must delegate to super, what the arguments to the method are, and even what the argument names are in some cases! You can't just go glomming classes together and expect it to go well unless you know the classes either don't use the same method names or agree very carefully on what the delgatable interfaces are.
https://www.python.org/download/releases/2.3/mro/
But; multiple inheritance is a beast in any language due to its complexity and bringing it up in a discussion of "magic" that python exposes beginners to is specious. It's true that C++ doesn't have this problem, because it has no super keyword and you must explicitly delegate everything, but also introduces the problem that you can have multiple instances of a base class and so has added complexity, virtual inheritance, to solve THAT problem. And tons of languages have a problem where omitting a call to "super" is logically required is not statically diagnosable.
2. Because it breaks the "ttl" feature of sudo for people who log in and out frequently (e.g., create and destroy terminal windows).
3. Because .bash_logout is only executed when a login shell exits.
Perhaps a similar but more elaborate solution could work to better mitigate this, though.