What is the purpose of the ‘positive value guarantee' of an absolute quantity?

[Spammed]

An ‘absolute quantity’ (which has a fixed reference point) is one thing.
A ‘delta quantity’ is, quite rightly, something else. So far, so good.

But I don’t see why an absolute quantity shouldn’t be negative.
What is the reasoning behind this?

Am I forced to use two absolute quantities just because my common point of reference lies between them?:
100 AD – 100 BC = 200 years
Why not simply:
100 AD – -100 AD = 200 years?

[mpusz]

Hi @Spammed, it is great to hear back from you 🤓

I am unsure if I understand your concerns. The code above works as you wrote, with the only difference that 100 AD and 100 BC are points and not absolute quantities. The points are not going away with the new design. 😉

Absolute quantities are anchored at well established zero ("nothing") and represent the total amount of t the quantity.

[Spammed]

I was triggered by your post "Why does Absolute - Delta result in a Delta?"
and mixed up 'absolute quantity' with 'point quantity' again, sorry.
"Is the 3-category model too complex for users?"
Mmh, at least for me, it seems to strike me every now and then...
...but as soon as I really think about it, it all makes perfect sense again.

[mpusz]

It is good to hear that there is some sense in it 😉

I am now attending the ISO C++ Committee meeting in the UK, and I am actually discussing the 3-category abstractions with the experts here who claim it is really important to provide it (they even mention a 4-category). I hope we will find a common solution that is powerful yet easy to understand and use.

[Spammed]

I just wanted to say that I think the documentation is brilliant,
and one can only imagine how much work has gone into it.

In particular, I feel much better informed thanks to the recent update of the 'Absolute article with Oliver Ronsten's feedback'.
Many thanks to you all.

[mpusz]

Thank you, @Spammed! It’s exactly this kind of feedback that motivates me to keep going through the next month 🤓

[chiphogg]

@Spammed, could you please link that article here? I don't remember if I've seen that version of it. 🙏

[mpusz]

@chiphogg, it is just the title of the commit that brought updates to the Absolute Quantities article. I update it with every new feedback I get and update the revision date below the intro.

@Spammed is one of the most active users who tracks actual commits being pushed to the repo. Thank you! 🙏
This also means that he knows each case that I mess up and need to fix my errors (which I always try to do ASAP) 🤣

[Spammed]

Reading and wondering – rightly or wrongly – isn’t much of an achievement.
Credit where credit is due (to you, not me)

But, hey, now I’m motivated to look into this in more detail... :-)