- > So to me it seems that we don't want abstractions when trying to study certain things about a whole system. Instead, we want to view all of its components and then build our understanding from there. Abstractions hide the things that we care about.
I disagree. My experience is that most problems require a very thorough understanding of a specific slice of a system. It is rare (again, in my experience) that solving a problem involves understanding the whole system. This becomes more true the larger and more complex the system is. Abstractions allow you to ignore the irrelevant pieces and focus on what matters.
- I agree with this. One way that I will go further is to say that “understanding of the whole system“ is a pretty fraught phrase. One person‘s holistic understanding is another person‘s gnostic gobble-de-gook. Realistically, they are all essentially just abstractions bounded by a different stopping rule. Just because one person‘s view of the whole system does not include what the GOOGLE engineer writing the code had for breakfast does not mean that that can’t be reasonably included.
The issue I think people have is that abstractions do not announce when they are insufficient or porous. This means that an abstraction which is perfectly trustworthy without further inspection for many years can suddenly become hazardous without warning.
- In a well-designed (or "proper") abstraction, we can deal with it in terms of its public interface. Two things that break abstractions are bugs and performance.
If you have either of those, then abstractions can be worse.
Another thing that is bad is the wrong abstractions, or abstraction inversion (https://en.wikipedia.org/wiki/Abstraction_inversion), where a layered system hides abstractions at the bottom from layers at the top, that top layers would nevertheless like to use, and reimplement, poorly. This happens surprisingly often.
But overall, I generally think that well-designed and factored abstractions are better than no abstractions at all.
- I disagree as well. Abstractions, or interfaces, define the contract between modules, and then you can reason about the system in terms of those contracts. Without the abstractions, you’d have to reason based on all the details of the whole program, which is obviously much harder. Abstractions are a form of divide and conquer.
Regarding the article’s point about diluting abstractions when new disparate features are required, a third alternative (to the two presented in the article) is often to provide alternative abstractions in parallel, each individually still focused and to-the-point, which prevents both changing and diluting the existing abstraction.
Regrading the article’s point about performance analysis, in principle you can specify performance guarantees for each abstraction. It’s more difficult to check them, but in theory a type system could even encode performance characteristics in an automatically checkable way.
- After reading the article I think the point stand. Not always but for example when working doing a RDBMS all the abstractions are active inhibitors and even hostile to do what should be done (easier) without all that.
And then you need to know that "no, all that IO sys call not do what you want, how yow want neither how is documented or even practiced by most" to take the most obvious case.
So, yes, this is a case where this quote is on point.
- The game Oxyd for the Atari ST was completely written in ~Oberon~ (no, it was Modula-2). Such an addictive game.
- I thought it was written in Modula-2. The Megamax compiler was quite popular. Oxyd is great but for some reason I prefer the monochrome display.
- Oh, "you are absolutely right". It was written in Modula-2. I got it mixed up.
But related languages anyway. :-)
Edit: Yes, I prefer the monochrome display and version too! Still using my monochrome SM124 monitor with Steinberg Cubase 3.1. It is a work horse. Only my eyes getting worse. Not the screen!! :-D