Units text output (standard vs engineering)

[mpusz]

ISO 80000 explicitly states that:

When symbols for quantities are combined in a product of two or more quantities, this combination is indicated in one of the following ways: ab, a b, a · b, a × b.

Here is the example of how it looks in practice:

Because of the above, we chose to print a · b for Standard Mode and a b for ASCII mode. Both cases inject spaces in the unit symbol which makes the output hard to parse.

Should we prefer standard compliance or engineering sanity here?

[mpusz]

I admit that a · b with monospace font looks bad :-(

[mpusz]

Also, rediscuss:

• Standard Mode as the default one (instead of ASCII)
• if %Aq modifier is enough to switch to ASCII or if there should be some global switch to do it?

[mpusz]

This document leaves hope that we can get rid of spaces at least for a Standard Format:

[kwikius]

This is probably more about input than output. IOW how easy is it to read a quantity back from a stream.

Here is an example in my quan library, which admittedly doesnt raise the bar that high, but may provide a place to start.

https://github.com/kwikius/quan-trunk/blob/master/quan_matters/examples/input.cpp.

My issue with spaces is that you move from lexing to parsing. Is the grammar LL1 https://en.wikipedia.org/wiki/LL_parser. Then you need to provide a parser

[mpusz]

Note to myself: another subject to discuss with ISO is #59.

[mpusz]

I removed the extra spaces some time ago. The SI brochure does not seem to provide additional spaces in its example, and it was just too ugly.