Comment by deathanatos

> Since UTF-32 allows storing every code point in a single code unit, you can also describe it that way, despite the fact that Python doesn't use a full 4 bytes per code point when it doesn't have to.

Python does not use UTF-32, even notionally. Yes, I know it uses a compact representation in memory when the value is ASCII, etc. That's not what I'm talking about here. |str| != |all UTF32 strings|; `str` and "UTF-32" are different things, as there are values in the former that are absent in the latter, and again, this is why encoding to utf8 or any utf encoding is fallible in Python.

Code points is not a meaningful metric, though I suppose strictly speaking, yes, len() is code points.

> I don't understand what you mean by "USV count".

The number of Unicode scalar values in the string. (If the string were encoded in UTF-32, the length of that array.) It's the basic building block of Unicode. It's only marginally useful, and there's a host of other more meaningful metrics, like memory size, terminal width, graphemes, etc. But it's more meaningful than code points, and if you want to do anything at any higher level of representation, USVs are going to be what you want to build off. Anything else is going to be more fraught with error, needlessly.

> It's what the Unicode standard says a character is.

The Unicode definition of "character" is not a technical definition, it's just there to help humans. Again, if I fed that definition to a human, and asked the same question above, <facepalm…> is 1 "character", according to that definition in Unicode as evaluated by a reasonable person. That's not the definition Python uses, since it returns 5. No reasonable person is looking at the linked definition, and then at the example string, and answering "5".

"How many smallest components of written language that has semantic value does <facepalm emoji …> have?" Nobody is answering "5".

(And if you're going to quibble with my use of definition (1.), the same applies to (2.). (3.) doesn't apply here as Python strings are not Unicode strings (again, |str| != |all Unicode strings|), (4.) is specific to Chinese.)

> "Character" is completely meaningful, as demonstrated by the fact the Unicode Consortium defines it, and by the fact that huge amounts of software has been written based on that definition, and referring to it in documentation.

A lot of people write bad code does not make bad code good. Ambiguous technical documentation is likewise not made good by being ambiguous. Any use of "character" in technical writing would be made more clear by replacing it with one of the actual technical terms defined by Unicode, whether that's "UTF-16 code point", "USV", "byte", etc. "Character" leaves far too much up to the imagination of the reader.