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Re: [css-grid] Should <custom-ident> in grid-template-rows/grid-template-columns exclude "span"?

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Wed, 26 Feb 2014 13:23:38 -0800
Message-ID: <CAAWBYDAAnAJ_jYihBS+7i5r5WiKbjMLM89Y1iZWdwGaXMyzoaQ@mail.gmail.com>
To: Daniel Holbert <dholbert@mozilla.com>
Cc: www-style <www-style@w3.org>
On Tue, Feb 25, 2014 at 6:06 PM, Daniel Holbert <dholbert@mozilla.com> wrote:
> Hi www-style,
>
> (This is about a related but slightly more subtle issue than my previous
> email[0]).
>
> Question: Should "span" be accepted as a valid <custom-ident> value, in
> the <line-names> list for the grid-template-columns and
> grid-template-rows properties?
>
> The keyword "span" does *not* appear in these properties' value
> definition[1], so it would seem that they should accept it. (based on
> the definition of <custom-ident>)
>
> HOWEVER: The keyword "span" *does* appear in the value definition for a
> *different* group of properties -- grid-row-start, grid-column-start,
> grid-row-end, and grid-column-end[2] -- and those properties *also* take
> a <custom-ident>, which can correspond to the same <custom-ident> used
> in grid-template-rows/grid-template-columns. (Both of them can refer to
> named lines.)
>
> So if we do allow 'span' as a <custom-ident> for
> grid-template-rows/grid-template-columns, it'll just be guaranteed to
> fail to match against any corresponding <custom-ident> in
> "grid-row-start" & friends (since it won't be a valid <custom-ident> for
> those properties).
>
> Maybe that's OK? (I tend to think it's OK; I'm just sanity-checking my
> understanding, while reviewing a patch to implement this parsing in
> Mozilla.)

You got it.  It's not explicitly disallowed, but ends up being useless
due to the way <custom-ident> is defined.  If we ever defined some
other method of referring to lines that didn't include "span" in the
grammar, you could use the lines there.

~TJ
Received on Wednesday, 26 February 2014 21:24:25 UTC

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