> On May 20, 2016, at 1:25 PM, Антон Жилин <antonyzhi...@gmail.com> wrote:
> Inline:
>
> 2016-05-20 20:58 GMT+03:00 John McCall <rjmcc...@apple.com
> <mailto:rjmcc...@apple.com>>:
> The transitivity rule plus the ability to define precedence relationships in
> both directions on a new precedence group allows a new precedence group to
> create a precedence relationship between existing unrelated precedence
> groups. This should be forbidden.
>
> Agreed, although there is an alternate solution to allow global-scope
> relationship definition.
> Trying to write it formally:
>
> ====begin====
> Precedence relationships that, by transitivity rule, create relationship
> between two imported groups, is an error. Example:
>
> // Module X
> precedencegroup A { }
> precedencegroup C { }
>
> // Module Y
> import X
> precedencegroup B { precedence(> A) precedence(< C) }
>
> This results in compilation error "B uses transitivity to define relationship
> between imported groups A and C".
> The rationale behind this is that otherwise one can create relationships
> between standard precedence groups that are confusing for the reader.
> ====end====
Seems good to me.
> What's the purpose of equality relationships between precedence groups?
>
> Agreed, will remove.
Ok.
> Your proposal should call out the special treatment of the Assignment and
> Ternary groups.
>
> Do you mean that most operators should define greater precedence than
> Assignment / Ternary? Or there should be some other special treatment?
Just that they have implicit members.
John.
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