[x3d-public] MFString quoting [was: interesting sample]

[Leonard Daly]

I agree that the document is wrong, unless there is someplace else in 
the document that indicates that the text is what appears after any 
legal XML parser. It may also be the case that an entity (e.g., ") 
is the same as the referenced character. I am not that familiar with 
that level of detail in XML syntax.

BTW, now is the time to propose significant changes in the structure of 
an encoding. None of the existing encodings are compatible with HTML, so 
it will be necessary to do work there anyway. It is a good time to 
improve upon things.

Leonard Daly




> 2017-04-26 5:41 GMT+02:00 Leonard Daly <Leonard.Daly at realism.com>:
>> If there is a reason that all attribute
>> values must be contained in quotes (perhaps it is a style requirement), then
>> an MFString would be encoded as
>>
>> ""this" "is" "a" "multiple"
>> "string" "field""
>>
>> Yes it's messy. We thought it was well documented, but the repeated
>> discussion has shown that not to be the case.
> As Andreas pointed out, your example
>
>    ""this" "is" "a" "multiple"
> "string" "field""
>
> seems to be disallowed by the specification (
> http://www.web3d.org/documents/specifications/19776-1/V3.3/Part01/EncodingOfFields.html#SFString
> ):
>
>    The MFString specifies zero or more SFStrings enclosed in single
> quotes (e.g., '"string1" "string2"').
>
> We completely agree with your notion that
>
>    '"this" "is" "a" "multiple" "string" "element"'
>
> should be equivalent to
>
>    ""this" "is" "a" "multiple"
> "string" "field""
>
> The proposed change to the specification (all to the section
> http://www.web3d.org/documents/specifications/19776-1/V3.3/Part01/EncodingOfFields.html#SFString
> ) would be to change this part:
>
> """""""
>    The MFString specifies zero or more SFStrings enclosed in single
> quotes (e.g., '"string1" "string2"').
>
>    NOTE  The construct
>
> "string3"
>
> is not a valid instance of an MFString. Such an MFString would be
> properly specified as
>
> '"string3"'
> """""""
>
> into this:
>
> """""""
>    The MFString specifies zero or more SFStrings, with each single
> string enclosed in double quotes (e.g., "string1" "string2"). Note
> that inside an XML attribute, you have to express a double quote using
> the " character entity, unless you enclose a whole XML attribute
> in single quotes.
>
>    NOTE  The construct
>
> "string3"
>
> is not a valid instance of an MFString. Such an MFString would be
> properly specified as
>
> '"string3"'
>
> or
>
> '"string3"'
>
> or
>
> ""string3""
> """""""
>
> For additional clarity, I would also add more prose and examples to
> explain when backslashes are needed. So I would change
>
> """""""
> EXAMPLE 2  Two instances of the double quote are contained in the
> following SFString field string:
>
> <Text string='"He said, \"Immel did it!\""' />
> """""""
>
> with this:
>
> """""""
> If a string is part of an MFString, and you want this string to
> contain a double-quote (for example, to actually show a double-quote
> using the Text node field "string") then you have to place a backslash
> before this double-quote. This rule applies regardless if you express
> double-quote as " or as " . This is necessary, to avoid treating
> the double-quote as a delimiter of strings on a MFString list.
>
> Consequently, if you want a string inside MFString to contain a
> backslash (for example, to actually show a backslash using the Text
> node field "string") then you have to write two backslashes. This is
> necessary, to avoid accidentally changing the meaning of a following
> double-quote character.
>
> EXAMPLE 2  All the following forms are correct and equivalent:
>
> <Text string='"He said, \"Immel did it!\""' />
>
> <Text string='"He said, \"Immel did it!\""' />
>
> <Text string='"He said, \"Immel did it!\""' />
>
> <Text string=""He said, \"Immel did it!\""" />
> """""""
>
> I think that this prose and examples clarifies the specification (or
> fixes it, depending on how do you interpret the current
> specification).
>
> P.S. I like your idea of
>
> <text>
>      <string>This</string>
>      <string>is</string>
>      <string>a</string>
>      <string>multiple</string>
>      <string>string</string>
>      <string>element</string>
> </text>
>
> But that is a larger change, requiring changes in the X3D browsers
> implementation. My proposed change requires no action from the
> implementations -- they already work like that.
>
> Regards,
> Michalis
>

-- 
*Leonard Daly*
3D Systems & Cloud Consultant
LA ACM SIGGRAPH Chair
President, Daly Realism - /Creating the Future/
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