Subject: Re: [xsl] format-number() causing problems to non-java implementators From: Joe English <jenglish@xxxxxxxxxxxxx> Date: Wed, 17 Jan 2001 10:05:16 -0800 |
[ Apologies if you see this twice -- the last message I sent doesn't seem to have gone through yet ] Miloslav Nic wrote: > BTW: Are there more functions causing problems for non Java > implementators? The requirement that numbers are represented as per IEEE 754 is troublesome. There's no portable way to deal with NaNs and infinities in C, C++, or most other languages (C9X makes things a little easier, but implementations aren't widely available yet.) The 'string()' function is astonishingly difficult to implement correctly without native language support, specifically clause 2, subclause 7, XPATH section 4.2: "there must be as many, but only as many, more digits as are needed to uniquely distinguish the number from all other IEEE 754 numeric values." I can't think of any document transformation tasks that actually require floating-point calculations; IMHO a much better choice would have been pointed infinite-precision rationals. Or -- to make things easier for languages other than Scheme, Haskell, ML, Lisp, etc. -- fixed-precision rationals with the numerator and denominator limited to 32 bits. C and Java programmers could use a pair of longs with 0/0 as the exceptional "NaN" value. (An exceptional value is needed to represent the result of number("...") where "..." isn't a valid number). Mandating IEEE 754 doubles seems gratuitously Java-centric to me. --Joe English jenglish@xxxxxxxxxxxxx XSL-List info and archive: http://www.mulberrytech.com/xsl/xsl-list
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