On Wednesday, February 08, 2012 17:52:17 Manfred Nowak wrote: > Jonathan M Davis wrote: > > thanks to how unicode works > > This does not mean, that the data structure representing a sequence of > "letters" has to follow exactly the "working" you cited above. That > data structure must only enable it efficiently. If a requirement for > sequences of letters is, that a sequence `s' of letters indexed by some > natural number `n' gives the letter `s[n]' and that is not efficiently > possible, than unicode and its "workings" are as maldesigned as the > alphabet Gutenberg has to take to produce books: > > take randomly an ancient book `b' and randomly a letter `c'. Then try > to verify that `b[ 314.159] == c'. Of course you are allowed to read > only one letter.
It is impossible to have a random access range of characters with unicode unless you have a range of graphemes - which would require a grapheme to be a struct of some kind which represented a character - either that or an array of arrays. So, you could have char[][] where each char[] is a grapheme. But as long as you're dealing with an array of code units or code points like we do now, it's impossible to have efficient random access of characters. Phobos currently takes the tact of treating a code point as a character, which _mostly_ works, but it's not correct. And while unicode could definitely have been designed better IMHO (e.g. forcing code point order with modifying code points and _not_ having multiple ways to generate the same character), the core problem is that you're forced to have variable length encodings. It wouldn't be feasible to have an integral value which represented _every_ single character, because of the combinatorial explosion caused by code points which modify other code points (e.g. subscript, superscript, cedille, etc.). So, there are problems which are just integral to the issue of designing unicode and which cannot be avoided no matter how good a job you do at designing unicode. And, of course, there are issues with the design on top of that. - Jonathan M Davis
