- 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