Incorrect meters to km

[lazaronixon]

1000.meters.to.kilometers is returning 1000. it should be 1

[halogenandtoast]

Howdy,

I think the issue here is that it's not clear what Measurement#to_f is doing, in this case, but to get the correct value you should be using Measurement#value here instead:

1000.meters.to.kilometers.value # => 1

The way switching between prefixes like kilo is by storing the information like this:

#<Alchemist::Measurement:0x00007fe57a2117d8 @value=1.0, @unit_name=:meters, @exponent=1000.0>

The idea at the time was that kilometers and meters are conceptually the same measurement just with an exponent, so calling Alchemist#to_f gives you the following:

def to_f
  (precise_value * exponent).to_f
end

Which describes it in terms of the base meters, instead of kilometers. I think I agree that this can be confusing so my plan is to resolve this for the "eventual" 1.0 release.