3 ms·

> BOMs (and especially the hilarious UTF-8 BOM) are strictly a legacy Microsoft/Windows thing How should a reader infer the bye order for a UCS-2 or UTF-16 fil

by entrope 13d ago

> BOMs (and especially the hilarious UTF-8 BOM) are strictly a legacy Microsoft/Windows thing How should a reader infer the bye order for a UCS-2 or UTF-16 file without a BOM? It seems like one would have to read until finding a code point that would be illegal under one ordering (but files might not include such a code point). Similarly, a UTF-8 BOM is a useful flag to distinguish UTF-8 from other text encodings. You are right that the ambiguity goes away if those other encodings do, but people don't want to rewrite their legacy files. Some people don't want to use two bytes for common non-ASCII characters, so they are really attached to ISO-8859 or Windows-1252 or koi8r or whatever. CJK languages have their own encodings that are more efficient for their languages. UTF-8 is great for English speakers, but it's a compromise for everyone else, so they might reasonably want incompatible systems for their own use. UTF-8 BOM is a good "magic" sequence to detect encoding as long as people have non-UTF-8 files.

flohofwoe 13d ago
> How should a reader infer the bye order for a UCS-2 or UTF-16 file without a BOM? Simple: switch to UTF-8 as the only encoding standard for sharing text data, keep UTF-32 as 'internal' runtime format for random access to codepoints, and get rid of all other legacy encodings (UCS-2, UTF-16, Extended ASCII with code pages, and all the other region specific encodings that popped up in the 70s and 80s because UTF-8 wasn't invented yet. This general switch to UTF-8 should have happend in the mid-to-late 1990s (e.g. together with the web becoming popular), and Microsoft alone is to blame for dragging this shit along for the next three decades. If all Microsoft tools would only save text data as UTF-8 starting by the end of the last century, but still support reading all sorts of encodings for a decade or so, the transition would have been finished by 2010. Alas, that never happened. And tbh, the file size argument for alphabets that don't fit into 7-bit ASCII doesn't really make sense anymore today where images and videos make up the vast majority of data volume.

by entrope 13d ago

flohofwoe 13d ago

> How should a reader infer the bye order for a UCS-2 or UTF-16 file without a BOM? Simple: switch to UTF-8 as the only encoding standard for sharing text data, keep UTF-32 as 'internal' runtime format for random access to codepoints, and get rid of all other legacy encodings (UCS-2, UTF-16, Extended ASCII with code pages, and all the other region specific encodings that popped up in the 70s and 80s because UTF-8 wasn't invented yet. This general switch to UTF-8 should have happend in the mid-to-late 1990s (e.g. together with the web becoming popular), and Microsoft alone is to blame for dragging this shit along for the next three decades. If all Microsoft tools would only save text data as UTF-8 starting by the end of the last century, but still support reading all sorts of encodings for a decade or so, the transition would have been finished by 2010. Alas, that never happened. And tbh, the file size argument for alphabets that don't fit into 7-bit ASCII doesn't really make sense anymore today where images and videos make up the vast majority of data volume.