[Bug 29723] [FO31] map:merge

https://www.w3.org/Bugs/Public/show_bug.cgi?id=29723

Abel Braaksma <abel.braaksma@xs4all.nl> changed:

           What    |Removed                     |Added
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                 CC|                            |abel.braaksma@xs4all.nl

--- Comment #4 from Abel Braaksma <abel.braaksma@xs4all.nl> ---
> unspecified     If duplicate keys are present, the effect is 
> implementation-defined; the implementation may choose one of the above 
> strategies for handling duplicates, or may choose some other strategy.
I would like to suggest that "unspecified" may not act as "combine" or
"reject", because that results in a functional and too unpredictable
difference. It should act as a "use-first", "use-last" or "use-either", in
other words, the only unpredictability of "unspecified" is whether the LH-value
or the RH-value of any given key is used.

If we wouldn't do this, a user cannot know whether he gets a combined sequence
for a given key, or whether he should add a try/catch.

This then also resolves another use-case: if the user knows that duplicate keys
exist, but with the same or exchangeable value, "unspecified" would become the
optimal strategy, where the implementer can choose either value and can
short-circuit evaluation, but will not error, or combine.

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Received on Wednesday, 20 July 2016 13:42:53 UTC