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Re: [widgets] Null in P&C

From: Thomas Roessler <tlr@w3.org>
Date: Tue, 2 Feb 2010 13:33:01 +0100
Cc: Thomas Roessler <tlr@w3.org>, public-webapps <public-webapps@w3.org>
Message-Id: <6C19E325-3EBC-44A1-B672-718B3A15194A@w3.org>
To: Marcos Caceres <marcosc@opera.com>
Is that a P&C specific concern or one that should better be covered in WebIDL?
--
Thomas Roessler, W3C  <tlr@w3.org>







On 2 Feb 2010, at 13:29, Marcos Caceres wrote:

> Hi,
> I had a discussion with an implementer who was a bit confused about the concept of "null" in the specification. The problem is that I kinda wrote the spec as if it was to be implemented in Java or JavaScript. This has resulted in confusion wrt how "null" is to be interpreted in languages that don't have that concept/data type.
> 
> So, in an effort to clarify that, I've added the following to Processing Rules section of P&C:
> 
> [[
> In the following algorithms, the concept of null is used as a special symbol to indicate that a variable has no data associated with it. For example, "let x be null" or "if y is empty, then return null".
> 
> Note: Although ECMAScript and Java support null as a native value type, there are some programming languages that have no notion of null or where null is problematic (e.g. C++). For those languages, it is OK for an implementation to substitute the null for some other value or symbol (or for nothing at all). For example, it is ok to have the value 0 represent null for the height of a widget as the height of a widget is defined as a non-negative integer greater than 0. In such a case, 0 would behave as if it is null.
> ]]
> 
> I don't have much experience programming in anything but Java and ECMAScript (why would anyone program in something else?!;)), so please let me know if it makes sense or if it could be better defined.
> 
> 
Received on Tuesday, 2 February 2010 12:33:09 GMT

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