Re: [apps-discuss] Review of: draft-yevstifeyev-abnf-separated-lists-02
Dave CROCKER <dhc@dcrocker.net> Sat, 11 December 2010 16:08 UTC
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Date: Sat, 11 Dec 2010 08:10:06 -0800
From: Dave CROCKER <dhc@dcrocker.net>
Organization: Brandenburg InternetWorking
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Cc: Mykyta Yevstifeyev <evnikita2@gmail.com>
Subject: Re: [apps-discuss] Review of: draft-yevstifeyev-abnf-separated-lists-02
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Folks, On 12/10/2010 12:38 PM, Dave CROCKER wrote: > FWIW, I'm not fond of this notation. The parenthetical seems clunky, especially > since it overloads the use of parens. I also don't like > putting it in between the upper/lower bound. > > Out of curiosity, why ^ rather than re-use #? I see that the new version of the notation is: > <n>^(<a>)^<m>element Having the same character used twice invites some parsing errors, though perhaps I'm being a purist on this point. But having the separator be buried within the repetition boundaries numbers this way still causes me some discomfort. At this point I am wondering whether it would not be cleaner to have the notation be: <n>*<m>[^(<a>)]element In other words, augment the existing repetition construct with a clean separator construct. The up-arrow only specifies a separator, it does not also specify repetition. Hence: 1*10^":"tag-val would be 1 to 10 tag-vals separated by colons, and *^" "words would be zero or more words separated by a space. I'm still not in love with the up-arrow, but can see an argument for not overloading #, which runs the risk that a reader won't know which definition of # is in force. Also the issue of allowing LWS or the like around the separator might best be expressed within the separator construct rather than be implied. (On reflection, I have a vague memory that one of the other concerns about # was that whitespace was implied.) Hence: 1*3^(*LWSP "," *LWSP) makes whitespace optional around the separator, whereas: 1*3^("," LWSP) requires exactly one whitespace character after each comma. d/ -- Dave Crocker Brandenburg InternetWorking bbiw.net
- [apps-discuss] Review of: draft-yevstifeyev-abnf-… Dave CROCKER
- Re: [apps-discuss] Review of: draft-yevstifeyev-a… Mykyta Yevstifeyev
- Re: [apps-discuss] Review of: draft-yevstifeyev-a… Julian Reschke
- Re: [apps-discuss] Review of: draft-yevstifeyev-a… Dave CROCKER
- Re: [apps-discuss] Review of: draft-yevstifeyev-a… Dave CROCKER
- Re: [apps-discuss] Review of: draft-yevstifeyev-a… Thomson, Martin
- Re: [apps-discuss] Review of: draft-yevstifeyev-a… Julian Reschke
- Re: [apps-discuss] Review of: draft-yevstifeyev-a… Thomson, Martin
- Re: [apps-discuss] Review of: draft-yevstifeyev-a… Julian Reschke
- Re: [apps-discuss] Review of: draft-yevstifeyev-a… Thomson, Martin
- Re: [apps-discuss] draft-yevstifeyev-abnf-separat… Mykyta Yevstifeyev
- Re: [apps-discuss] draft-yevstifeyev-abnf-separat… Dave CROCKER
- Re: [apps-discuss] draft-yevstifeyev-abnf-separat… Julian Reschke
- Re: [apps-discuss] draft-yevstifeyev-abnf-separat… Thomson, Martin
- Re: [apps-discuss] draft-yevstifeyev-abnf-separat… Dave CROCKER
- Re: [apps-discuss] draft-yevstifeyev-abnf-separat… Paul Overell