Re: [Json] The names within an object SHOULD be unique.

[Vinny A <[e-mail]>]

On Jun 6, 2013, at 12:45 PM, Allen Wirfs-Brock <[e-mail]> wrote:
> Allen Wirfs-Brock
> ECMAScript Language Spec. Project Editor

> What I would say, as a replacement for the current text  <section 2.2> is:
> 
>         The names within an object SHOULD be unique.  If a key is duplicated, a parser MUST take  <<use?? interpret??>> only the last of the duplicated key pairs.

Just to be clear here, ECMA is OK with using MUST in regards to the last key pair?  

Because we already have proposed language that says that, but one of the points under contention on this list is what to do with duplicated key pairs.

Is the following language acceptable to ECMA (disclaimer: original text by Paul,  modifications by me):


On Jun 6, 2013, at 10:24 AM, Paul Hoffman <[e-mail]> wrote:
> The new text should use language that is already in RFC 4627; "key" is not such a word. To be fair to implementers, the new document also needs to deal with both emitters and parsers.
> 
> Proposal:
> 
> In Section 2.2:
> Current:
>   The names within an object SHOULD be unique.
> Proposed:
>   If the names within an object are not unique, the result of parsing the 
>   object is unpredictable, and the parse may even fail completely. Thus,
>   the names within an object SHOULD be unique.
> 
> In Section 4, add a new paragraph:
>   If a parser encounters an object with duplicate names, the parser MAY
>   fail to parse the JSON text; if the parser accepts objects with duplicate
>   names, it SHOULD accept only the last name/value pair that has the
>   duplicate name. 

If we have to recommend to both parsers and emitters, I'd like to make a slight change to your wording:

In Section 2.2:
Current:
    The names within an object SHOULD be unique.
Proposed:
   The names within an object SHOULD be unique. Non-unique names have unpredictable effects (refer to sections 4 & 5).

In Section 4 (Parsers) add a new paragraph:
  If a parser encounters an object with duplicate names, the parser MAY fail to parse the JSON text; if the parser accepts objects with duplicate names, it MUST accept only the last name/value pair that has the duplicate name. 

In Section 5 (Generators) add a new paragraph:
   A JSON generator SHOULD not duplicate names. If duplicate names are generated, the authoritative name/value pair MUST be listed last.


-----------------
Vinny
www.jsontest.com