- From: Julian Reschke <julian.reschke@gmx.de>
- Date: Wed, 12 Aug 2009 14:07:04 +0200
- To: Ian Hickson <ian@hixie.ch>
- CC: Daniel Stenberg <daniel@haxx.se>, "public-html@w3.org" <public-html@w3.org>
Ian Hickson wrote: > On Wed, 12 Aug 2009, Julian Reschke wrote: >> Ian Hickson wrote: >>> On Wed, 12 Aug 2009, Daniel Stenberg wrote: >>>> Combined, it makes it a pain to write a formal syntax spec from. >>> With HTML5 I've found that rather than defining formal syntaxes for this >>> kind of thing, it's easier just to define imperative parsing steps that lead >>> to the right behaviour. >>> >>> For example: >>> >>> http://www.whatwg.org/specs/web-apps/current-work/#rules-for-parsing-floating-point-number-values >> They might be useful for implementers of parsers, but they are almost >> unreadable for producers. > > They're not intended for producers (in fact they're hidden in the HTML5 > spec when you select the "author" option) so that's not really that > surprising. For producers, you want the much simpler description of what > is valid, which often has little bearing on the parsing rules. (moving this thread over to public-html) Those descriptions are simpler, but, at least for my taste, still unnecessary hard to read; usage of ABNF would make it more readable. For instance, when I look at "month" I find: "2.4.5.1 Months A month consists of a specific proleptic Gregorian date with no time-zone information and no date information beyond a year and a month. [GREGORIAN] A string is a valid month string representing a year year and month month if it consists of the following components in the given order: 1. Four or more digits, representing year, where year > 0 2. A U+002D HYPHEN-MINUS character (-) 3. Two digits, representing the month month, in the range 1 ≤ month ≤ 12" So it defines "month" (in bold) to be a date, consisting of a year and a month (non-bold). This is confusing. Why not simply say: year = 4*DIGIT ; 4 or more digits, year > 0 month = 2DIGIT ; 2 digits, 1 <= month <= 12 month-string = year "-" month ? BR, Julian BR, Julian
Received on Wednesday, 12 August 2009 12:19:06 UTC