On 02/20/12 16:47, Brendan Eich wrote: > Andrew Oakley wrote: >> Issues only arise in code that tries to treat a string as an array of >> 16-bit integers, and I don't think we should be particularly bothered by >> performance of code which misuses strings in this fashion (but clearly >> this should still work without opt-in to new string handling). > > This is all strings in JS and the DOM, today. > > That is, we do not have any measure of code that treats strings as > uint16s, forges strings using "\uXXXX", etc. but the ES and DOM specs > have allowed this for > 14 years. Based on bitter experience, it's > likely that if we change by fiat to 21-bit code points from 16-bit code > units, some code on the Web will break.
Sorry, I don't think I was particularly clear. The point I was trying to make is that we can *pretend* that code points are 16-bit but actually use a 21-bit representation internally. If content requests proper Unicode support we simply switch to allowing 21-bit code-points and stop encoding characters outside the BMP using surrogate pairs (because the characters now fit in a single code point). > And as noted in the o.p. and in the thread based on Allen's proposal > last year, browser implementations definitely count on representation > via array of 16-bit integers, with length property or method counting same. > > Breaking the Web is off the table. Breaking implementations, less so. > I'm not sure why you bring up UTF-8. It's good for encoding and decoding > but for JS, unlike C, we want string to be a high level "full Unicode" > abstraction. Not bytes with bits optionally set indicating more bytes > follow to spell code points. Yes, I probably shouldn't have brought up UTF-8 (we do store strings using UTF-8, I was thinking about our own implementation). The intention was not to "break the web", my comments about issues when strings were misused were purely *performance* concerns, behaviour would otherwise remain unchanged (unless full Unicode support had been enabled). -- Andrew Oakley _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
