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RE: Calling attention: Constraints and MinMaxValues

From: Travis Leithead <travis.leithead@microsoft.com>
Date: Mon, 6 May 2013 16:40:36 +0000
To: Harald Alvestrand <harald@alvestrand.no>, "public-media-capture@w3.org" <public-media-capture@w3.org>
Message-ID: <4ac18bd3c7754b3f8e30b489b862c362@SN2PR03MB077.namprd03.prod.outlook.com>


From: Harald Alvestrand [mailto:harald@alvestrand.no] 

> dictionary MinMaxConstraint {
>      any max;
>      any min;
> };
>
> (I think this last needs to have a few question marks added, so that min or max can be omitted; otherwise, we can't express a pure "min" or "max" 
value any more. Detail.)

No, question marks only mean that the value can take null (literally). By definition, all of a dictionary's members are optional. Here's the relevant text from WebIDL [1]:

"A dictionary value of type D can have key-value pairs corresponding to the dictionary members defined on D and on any of D's inherited dictionaries. ***On a given dictionary value, the presence of each dictionary member is optional.*** When specified in the dictionary value, a dictionary member is said to be present, otherwise it is not present. Dictionary members can also optionally have a default value, which is the value to use for the dictionary member when passing a value to a platform object that does not have a specified value. Dictionary members with default values are always considered to be present."

[1] http://dev.w3.org/2006/webapi/WebIDL/#idl-dictionaries
Received on Monday, 6 May 2013 16:42:21 UTC

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