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0 pointsRetric3mo ago0 comments

> I can't think of any.

Incorrect definition = incorrect interpretation. I edited this a few times but the separation is you can use an abstraction even if you maintain access to the implementation details.

> assembler

Assembly language which is a different thing. Initially there was no assembler, someone had to write one. In the beginning every line of code had direct access to all memory in part because limited access required extra engineering.

Though even machine code itself is an abstraction across a great number of implementation details.

> I don't see this as an abstraction as much as a simple engineering compromise (of accuracy) dictated by constraint (CPU time/solenoid wear/whatever), because you're not hiding complexity as much as ignoring it.

If it makes you feel better consider the same situation with 5 senators X of which have failed. The point is you don’t need to consider all information at every stage of a process. Instead of all the underlying details you can write code that asks do we have enough information to get a sufficiently accurate speed? What is it?

It doesn’t matter if the code could still look at the raw sensor data, you the programmer prefer the abstraction so it persists even without anything beyond yourself enforcing it.

IE: “hiding details that otherwise might make access more challenging”

You can use TCP/IP or anything else as an abstraction even if you maintain access to the lower level implementation details.

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nomel3mo ago

I genuinely appreciate your response, because there's a good chance it'll result in me changing my perspective, and I'm asking these questions with that intent!

> You are thinking of assembly language which is a different thing. Initially there was no assembler, someone had to write one.

This is why I specifically mention opcodes. I've actually written assemblers! And...there's not much to them. It's mostly just replacing the names given to the opcodes in the datasheet back to the opcodes, with a few human niceties. ;)

> consider the same situation with 5 senators X of which have failed

Ohhhhhhhh, ok. I kind of see. Unfortunately, I don't see the difference between abstraction and encapsulation here. I see the abstraction as being speed as being the encapsulation of a set of sensors, ignoring irrelevant values.

I feel like I'm almost there. I may have edited my previous comment after you replied. My "no procrastination" setting kicked in, and I couldn't see.

I don't see how "The former is about semantic levels, the later about information hiding." are different. In my mind, semantic levels exist as compression and encapsulation of information. If you're saying encapsulation means "black box" then that could make sense to me, but "inaccessible" isn't part of the definition, just "containment".

johnmwilkinson3mo ago

Computer Science stole the term abstraction from the field of Mathematics. I think mathematics can be really helpful in clearing things up here.

A really simple abstraction in mathematics is that of numeric basis (e.g. base 10) for representing numbers. Being able to use the symbol 3 is much more useful than needing to write III. Of course, numbers themselves are an abstraction- perhaps you and I can reason about 3 and 7 and 10,000 in a vacuum, but young children or people who have never been exposed to numbers without units struggle to understand. Seven… what? Dogs? Bottles? Days? Numbers are an abstraction, and Arabic digits are a particular abstraction on top of that.

Without that abstraction, we would have insufficient tools to do more complex things such as, say, subtract 1 from 1,000,000,000. This is a problem that most 12 year olds can solve, but the greatest mathematicians of the Roman empire could not, because they did not have the right abstractions.

So if there are abstractions that enable us to solve problems that were formerly impossible, this means there is something more going on than “hiding information”. In fact, this is what Dijkstra (a mathematician by training) meant when he said:

The purpose of abstraction is not to be vague, but to create a new semantic level in which one can be absolutely precise

When I use open(2), it’s because I’m operating at the semantic level of files. It’s not sensible to think of a “file” at a lower level: would it be on disk? In memory? What about socket files? But a “file” isn’t a real thing, it’s an abstraction created by the OS. We can operate on files, these made up things, and we can compose operations together in complex, useful ways. The idea of a file opens new possibilities for things we can do with computers.

I hope that explanation helps!

johnmwilkinson3mo ago

Expanding on this regarding the difference between abstraction vs encapsulation: abstraction is about the distillation of useful concepts while encapsulation is a specific tactic used to accomplish a behavior.

To continue with the idea of numbers, let’s say you asked someone to add 3 and 5. Is that encapsulation? What information are you hiding? You are not asking them to add coins or meters or reindeer. 3 and 5 are values independent of any underlying information. The numbers aren’t encapsulating anything.

Encapsulation is different. When you operate a motor vehicle, you concern yourself with the controls presented. This allows you, as the operator, to only need a tiny amount of knowledge to interact with an incredibly complex machine. This details have been encapsulated. There may be particular abstraction present, such as the notion of steering, acceleration, and breaking, but the way you interact with these will differ from vehicle to vehicle. Additionally, encapsulation is not concerned with the idea of steering, it is concerned with how to present steering in this specific case.

The two ideas are connected because using an abstraction in software often involves encapsulation. But they should not be conflated, out the likely result is bad abstractions and unwieldy encapsulation.

RetricOP3mo ago

> It's mostly just replacing the names given to the opcodes in the datasheet back to the opcodes

Under the assumption that the input data is properly formatted you can generate machine code. This is however an abstraction which can fail as nothing forces a user to input valid files.

So we have an abstraction without any encapsulation.

nomel3mo ago

I can only see that as being the case if you weren't aware of it. Otherwise, the awareness would be explicit intent to fail on malformed input, which seems like just as much as an encapsulation?

But, that's a great example! Thank you. This makes it clear that I'm probably sometimes wrong. ;)

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nomel3mo ago

I genuinely appreciate your response, because there's a good chance it'll result in me changing my perspective, and I'm asking these questions with that intent!

> You are thinking of assembly language which is a different thing. Initially there was no assembler, someone had to write one.

> consider the same situation with 5 senators X of which have failed

I feel like I'm almost there. I may have edited my previous comment after you replied. My "no procrastination" setting kicked in, and I couldn't see.

johnmwilkinson3mo ago

Computer Science stole the term abstraction from the field of Mathematics. I think mathematics can be really helpful in clearing things up here.

The purpose of abstraction is not to be vague, but to create a new semantic level in which one can be absolutely precise

I hope that explanation helps!

johnmwilkinson3mo ago

RetricOP3mo ago

> It's mostly just replacing the names given to the opcodes in the datasheet back to the opcodes

Under the assumption that the input data is properly formatted you can generate machine code. This is however an abstraction which can fail as nothing forces a user to input valid files.

So we have an abstraction without any encapsulation.

nomel3mo ago

I can only see that as being the case if you weren't aware of it. Otherwise, the awareness would be explicit intent to fail on malformed input, which seems like just as much as an encapsulation?

But, that's a great example! Thank you. This makes it clear that I'm probably sometimes wrong. ;)

j / k navigate · click thread line to collapse