[PATCH 1/2] Models: translate the user entered weight units

[Linus Torvalds]

On Fri, Jan 3, 2014 at 9:08 AM, Dirk Hohndel <dirk at hohndel.org> wrote:
>
>> In particular, remember: if the string is some translation of the
>> standard unit, matching _that_ doesn't even *matter*, because it will
>> be matched by default by simply matching the locale setting (which
>> will always match the translated unit name, since that is where it
>> came from). See?
>
> I don't understand that last sentence. I think we should compare to
> "lbs" and tr("lbs") and accept both. Same for "kg".

The point is, nobody sane likely *uses* tr("lbs"). There's no reason
to ever compare it. And "kg" is either always "kg" or falls under the
same heading.

Let me explain the "nobody uses tr("lbs")" by a practical example.

Let's say that you have set your units to imperial, but are in a
German locale, so that subsurface translates a 10kg weight to "22 US
Pfund".

Now, that means that if somebody just edits the number to fix it up to
"28 US Pfund", we'll actually see that "US Pfund" part, but it doesn't
actually *matter* whether we match it or not. The only thing that
matters is that we don't match "kg". Because if we don't match any
unit at all, we'll use our user units - which are lbs. So we do the
right thing.

And if the user is in metric, and the weight started out as "10kg",
but the user realized that "Ooops, I'm in Hawaii, and their weights
are all imperial, I'd better fix it to be "10 lbs" instead, I can
pretty much guarantee that no sane German ever will come up with "US
Pfund" on his own (ie if that string wasn't already fed to him
*because* he was in an imperial locale). He might try a lot of things,
but the likelihood that he'd enter that random string is basically
zero. Agreed? But at the same time, he'll be *physically* in a locale
where "lbs" actually does make some sense (ie it might be written on
the dive board).

So reasonably, I don't think there's a lot of upside to translating
"lbs". All sane countries use metric measures and will either use "kg"
or whatever translation of it (but not matching it won't matter, since
we'll default to "kg" in a metric unit model anyway).

So the *only* time you actually care about trying to match the unit
string is when it's a *foreign* unit string, and that by definition
means that you'll not know what the hell those crazy furriners use,
because by definition, that foreign unit is foreign in your locale.
But "kg" and "lbs" you at least have a *chance* with. If you're
American, you might just know about "kg" or at least ask your dive
buddy. And if you're not, you're going to write something random,
because you'll have no f*cking idea what a pound is in your language
anyway.

(Side note: I think we might want to change the three-character "lbs"
comparison to a two-character "lb" comparison, because somebody who
actually does know what they are doing might well write "10lb").

                   Linus