Could use support for engineering decimal units

[wandererfan]

We're making good progress on the output side:

CivilUnits2.png (27.11 KiB) Viewed 1323 times

CivilUnits3.png (21.35 KiB) Viewed 1323 times

But there are problems on the input side. The expression parser (??) doesn't like degrees + feet(') + inches("). If I try to enter an Angular constraint (say 60*24'10") I get 1.0 back as a value. Need to do some digging.

[Joel_graff]

But there are problems on the input side. The expression parser (??) doesn't like degrees + feet(') + inches("). If I try to enter an Angular constraint (say 60*24'10") I get 1.0 back as a value. Need to do some digging.

That looks awesome. No idea what to suggest regarding the expression parser, unless we replace the ' and " with 'm' and 's', or something...

Still, thanks for the effort. It looks really good!

[wandererfan]

No idea what to suggest regarding the expression parser, unless we replace the ' and " with 'm' and 's', or something...

l/c 'm' is taken for metres, l/c 's' is taken for seconds(time), so I'm going with 'M' & 'S' for now. We're definitely getting closer:

AngleDataEntry.png (16.77 KiB) Viewed 1280 times

Seconds are displayed using the global decimal place setting. Do you need decimal place on Seconds? Looks ugly to me, but that's just aesthetics, not functionality.

FracSeonds.png (11.74 KiB) Viewed 1280 times

[Joel_graff]

Seconds are displayed using the global decimal place setting. Do you need decimal place on Seconds? Looks ugly to me, but that's just aesthetics, not functionality.

For design purposes, the nearest second should be sufficient - we don't design to any greater precision than that. Fractions of seconds are more of a concern in surveying contexts, though having the ability may eventually be necessary. The nearest half-second (tenth) might make for a good compromise, there.

As for the notation, I'm absolutely fine with it for development, but in a production design environment, it wouldn't be acceptable. That said, it may be useful to consider a feature request to allow for repurposing unit symbology. No doubt some unpleasant abstraction would be in order to make that happen... :/ Anyway, kinda hard to ask for that, though, unless I knew it would be a benefit somewhere else, since it's absolutely not an issue for what I'm doing.

[wandererfan]

For design purposes, the nearest second should be sufficient - we don't design to any greater precision than that.

I'm going with integer seconds and "M"/"S" for data entry. If we need decimals on the seconds someday we can change it then.

Degrees can be "deg" or "°".

TechDraw has been modified to display dd°mm'ss", but it doesn't have to handle data entry. It might be possible to display with proper symbols in Sketcher (or other workbenches) too, but I'll have to look into it.

We're stuck with M&S for data entry for the near future. The Unit system expects each symbol to belong to 1 unit. Changing that looks like a big job from here.

wf

[Joel_graff]

We're stuck with M&S for data entry for the near future. The Unit system expects each symbol to belong to 1 unit. Changing that looks like a big job from here.

Yeah, I had a funny feeling that was the case - I've dealt with issues like that before in other projects... I know how ugly it can get.

That said, having a unit system that's user-customizable seems like something that should be in a long-term plan, if nothing else.

There's a lot of legacy unit conventions out there still in use, many of which borrow from others, and the differences can be subtle or significant... In fact, it wasn't so long ago that US surveyors still used units of 'rods' and 'chains' (I suspect there's still a few applications out there that use them). So a way to allow for creating unique / niche unit systems local to a workbench (or, more sensibly, a document), and a way to re-use symbols across (or even within) unit systems seems like a valuable feature to me.

Well, crap. Now I'm interested in solving this problem.

[wandererfan]

Well, crap. Now I'm interested in solving this problem.

"If you want anything done, ask a busy man."

[Joel_graff]

"If you want anything done, ask a busy man."

Can you point me to the code? I really can't commit to dealing with it, but I'm curious... which has to count for something. If nothing else, understanding the size and scale of the needed solution might convince me just to keep my mouth shut.

[wandererfan]

Can you point me to the code?

The easy part is creating a new Unit Schema. That happens in "src/Base/UnitsSchemaImperial1.*"

The hard part is making the new schema valid for input fields. That happens in "src/Base/Quantity*.*". There is a formal grammar set up with a lexer and parser that generate code to interpret your schema. flex and bison are the tools involved.

[wandererfan]

git commit 00e6e376c9 and git commit 99074228.

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