[jstimpfle]

> Could you please expand upon your idea that [..] a hierarchical structure of "blackboxes" [...] is bad?

You'll notice yourself when you try to actually apply this idea in practice. But a possible analogy is: How many tall buildings are around your place, what was their cost, how groundbreaking are they? Chances are, most buildings around you are quite low. Low buildings have a higher overhead in space cost, so especially in denser cities, there is a force to make buildings with more levels.

But after some levels, there are diminishing returns from going even higher, compared to just creating an additional building of the same size. And overhead is increasing. Higher up levels are more costly to construct, and they require a better foundation. We can see that most higher buildings are quite boring: how to construct them is well-understood, there isn't much novelty. There just aren't that many types of buildings that have all these properties: 1) tall/many levels 2) low overall cost of creation and maintenance 3) practical 4) novel.

With software components it's similar. There are a couple of ideas that work well enough such that you can stack them on top of each other (say, CPU code on top of CPUs on top of silicon, userspace I/O on top of filesystems on top of hard drives, TCP sockets on top of network adapters...) which allows you to make things that are well enough understand and robust enough and it's really economical to scale out on top of them.

But also, there isn't much novelty in these abstractions. Don't underestimate the cost in creating a new CPU or a new OS, or new software components, and maintaining them!

When you create your own software abstractions, those just aren't going to be that useful, they are not going to be rock-solid and well tested. They aren't even going to be that stable -- soon a stakeholder might change requirements and you will have to change that component.

So, in software development, it's not like you come up with rock-solid abstractions and combine 5 of those to create something new that solves all your business needs and is understandable and maintainable. The opposite is the case. The general, pre-made things don't quite fit your specific problem. Their intention was not focused to a specific goal. The more of them you combine, the less the solution fits and the less understandable it is and the more junk it contains. Also, combining is not free. You have to add a _lot_ of glue to even make it barely work. The glue itself is a liability.

But OOP, as I take it, is exactly that idea. That you're creating lots of perfect objects with a clear and defined purpose, and a perfect implementation. And you combine them to implement the functional requirements, even though each individual component knows only a small part of them, and is ideally reusable in your next project!

And this idea doesn't work out in practice. When trying to do it that way, we only pretend to abstract, we just pretend to reuse, and in the process we add a lot of unnecessary junk (each object/class has a tendency to be individually perfected and to be extended, often for imaginary requirements). And we add lots of glue and adapters, so the objects can even work together. All this junk makes everything harder and more costly to create.

> structure things as a loosely coupled set of smaller components

Don't build on top of shoddy abstractions. Understand what you _have_ to depend on, and understand the limitations of that. Build as "flat" as possible i.e. don't depend on things you don't understand.

[ksclk]

Thanks a ton! While I don't have the experience to understand all of it, I appreciate your writing, like the sibling poster (and that you didn't delete your comment)!

It reminds me of huge enterprise-y tools, which in the long run often are more trouble than they're worth (and reimplementing just the subset you need perhaps would be better), and (the way you speak about OOP) bloated "enterprise" codebases with huge classes and tons of patterns, where I agree making things leaner and less generic would do a lot of good.

At first however I thought that you're against the idea of managing complexity by hierarchically splitting things into components (i.e. basically encapsulation), which is why I asked for clarification, because this idea seems fundamental to me, and seeing that someone is against it got me interested. I think now though that you're not against this idea, and you're against having overly generic abstractions (components? I'm not sure if I'm using the word "abstractions" correctly here) in your stack, because they're harder to understand, which I understand. I assume this is what blackbox means here.

Does it sound correct?

[jstimpfle]

I'm not at all about decomposition and encapsulation. But I do think that the idea of _hierarchical_ decomposition can easily be overdone. The hierarchy idea might be what leads to building "on top" of leaky abstractions.

[i_am_a_peasant]

> When you create your own software abstractions, those just aren't going to be that useful, they are not going to be rock-solid and well tested. They aren't even going to be that stable -- soon a stakeholder might change requirements and you will have to change that component.

I also think it's about how many people you can get to buy-in on an abstraction. There probably are better ways of doing things than the unix-y way of having an OS, but so much stuff is built with the assumption of a unix-y interface that we just stick with it.

Like why can't I just write a string of text at offset 0x4100000 on my SSD? You could but a file abstraction is a more manageable way of doing it. But there are other manageable ways of doing it right? Why can't I just access my SSD contents like it's one big database? That would work too right? Yeah but we already have the file abstraction.

>But OOP, as I take it, is exactly that idea. That you're creating lots of perfect objects with a clear and defined purpose, and a perfect implementation. And you combine them to implement the functional requirements, even though each individual component knows only a small part of them, and is ideally reusable in your next project!

I think OOP makes sense when you constrain it to a single software component with well defined inputs and outputs. Like I'm sure many GoF-type patterns were used in implementing many STL components in C++. But you don't need to care about what patterns were used to implement anything in <algorithm> or <vector>. you just use these as components to build a larger component. When you don't have well defined components that just plug and play over the same software bus, no matter how good you are in design patterns it's gonna eventually turn into spagetti un-understandable mess.

I'm really liking your writing style by the way, do you have a blog or something?

[jstimpfle]

I think I agree with your "buy-in idea", but adding that the Unix filesystem abstraction is almost as minimal as it gets, at least I'm not aware of a simpler approach in existence. Maybe subtract a couple small details that might have turned out as not optimal or useful. You can also in fact write a string to an offset on an SSD (open e.g. /dev/sda), you only need the necessary privileges (like for a file in a filesystem hierarchy too btw).

A database would not work as mostly unstructured storage for uncoordinated processes. Databases are quite opinionated and require global maintenance and control, while filesystems are less obtrusive, they implement the idea of resource multiplexing using a hierarchy of names/paths. The hierarchy lets unrelated processes mostly coexist peacefully, while also allowing cooperation very easily. It's not perfect, it has some semantically awkward corner cases, but if all you need is multiplexing a set of byte-ranges onto a physical disk, then filesystems are a quite minimal and successful abstraction.

Regarding STL containers, I think they're useful and useable after a little bit of practice. They allow you to get something up and running quickly. But they're not without drawbacks and at some point it can definitely be worthwhile to implement custom versions that are more straightforward, more performant (avoiding allocation for example), have better debug performance, have less line noise in their error messages, and so on. The most important containers in the STL are quite easy to implement custom versions with fewer bells and whistles for. Maybe with the exception of map/red-black tree which is not that easy to implement and sometimes the right thing to use.

[jstimpfle]

> I'm really liking your writing style by the way, do you have a blog or something?

Thank you! I don't get to hear that often. I have to say I was almost going to delete that above comment because it's too long, the structure and build up is less than clear, there are a lot of "just" words in it and I couldn't edit anymore. I do invest a lot of time trying to write comments that make sense, but have never seen myself as a clear thinker or a good writer. To answer your question, earlier attempts to start a blog didn't go anywhere really... Your comment is encouraging though, so thanks again!