On 2016-08-28 18:44, Ken Kundert wrote:
When working with a general purpose programming language, the above numbers
become:
780kpc -> 7.8e+05
108MPa -> 1.08e+08
600TW -> 6e+14
3.2Gb -> 3.2e+09
53pm -> 5.3e-11
$8G -> 8e+09
Notice that the numbers become longer, harder to read, harder to type, harder to
say, and harder to hear.
You've continually repeated this assertion, but I don't buy it. For
the general case, exponential notation is easier to read because you can
always see exactly what the exponent is as a number. To read SI units,
you have to know all the SI prefixes. This may well be common within
scientific communities, but to say that it is "easier" is really a bit
much. The same is true of "harder to type". "kpc" is three characters;
e+5 is also three (note that you don't need to write e+05), and one of
those is a number that transparently indicates how many places to move
the decimal, whereas all of the letters in "kpc" are opaque unless you
already know what the number is meant to represent.
If you have concrete evidence (e.g., from actual user experience
research) showing that it is across-the-board "easier" to read or type
SI prefixes than exponential notation, that would be good to see. In
the absence of that, these assertions are just doubling down on the same
initial claim, namely that adding SI units to Python would make things
more convenient *for those using it to compute with literally-entered
quantities in SI units*. I quite agree that that is likely true, but to
my mind that is not enough to justify the disruption of adding it at the
syntactic level. (Unless, again, you have some actual evidence showing
that this particular kind of use of numeric literals occurs in a large
proportion of Python code.)
> Before we expend any more effort on this topic, let's put aside the
question of
> how it should be done, or how it will be used after its done, and
just focus on
> whether we do it at all. Should Python support real numbers specified
with SI
> scale factors as first class citizens?
My current opinion is no. There are lots of things that are common.
(Should we include a spellchecker in Python because many people
frequently make spelling errors?) The fact that SI units are de rigeur
in the physical science community isn't enough. I would want to see
some actual attempt to quantify how much benefit there would be in the
PYTHON community (which of course includes, but is not limited to, those
using Python for physical-science computations).
--
Brendan Barnwell
"Do not follow where the path may lead. Go, instead, where there is no
path, and leave a trail."
--author unknown
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