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[css-animations] More ambiguity questions with the animation shorthand

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Tue, 27 May 2014 14:10:03 -0700
Message-ID: <CAAWBYDAGD7d3RvBCP+VszeM2sD8DGo3OiSPmmTh2V_2xnZFqNQ@mail.gmail.com>
To: www-style list <www-style@w3.org>
At the F2F, we agreed to some principles for handling <custom-ident>
when it can't be disambiguated positionally, based on the 'animation'
shorthand.  Basically, values should be assigned to the longhands
greedily, with the <custom-ident> longhand having the lowest priority
when claiming a value.  That way, "animation: ease-in linear;" gets
parsed with a timing-function or "ease-in" and a name of "linear".

This works fine when the value spaces that <custom-ident> might clash
with contain *only* idents, but it's less clear what to do when they
can contain other things, like functions.  In particular, how should
we parse "animation: ease-in steps(2);"?  Should we greedily assign
ease-in to timing-function, and then fail to parse the property when
we hit the function?  Or should we allow new values to reassign
things, so we get a name of "ease-in" and a timing-function of
"steps(2)"?

The latter is basically the list-style behavior, where you can't tell,
upon seeing a "none", whether it should be assigned to list-style-type
or list-style-image until you see the rest of the property.

~TJ
Received on Tuesday, 27 May 2014 21:10:50 UTC

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