Re: Possible bug with null document in libyaml

Bill and Ingy,

Thanks Ingy. I finally understood the importance of 
providing a way to serialize zero objects by reading 
your post. Before that, I was thinking as the same as Bill.

Then, according to the spec, a YAML serializer can encode 
an empty string (in YAML 1.1 document) or a null object (in 
YAML 1.2 document) as an empty node in all the cases except 
for the one where the whole YAML stream becomes empty.
I think an explicit warning should be given in the spec 
to clarify this point with some explanation of the
importance of providing a way to serialize zero objects.
It will be very much helpful.

In addition, I point out that any empty string should not
be encoded into empty nodes in YAML 1.1 document in 
any sense because it will not be compatible with YAML 1.2. 
In YAML 1.2 spec, an empty node represents a null object.
So, anyways, all the YAML 1.1 serializers should be patched 
to encode all the empty strings in quoted styles "" or ''.


BTW, I do not think a YAML 1.1 library will accept "x" as a 
valid YAML stream if the library strictly implements the 
specification. In YAML 1.1, a plain scalar node must be 
followed by s-l-comments that contains at least one line 
break. So, "x\n" is a valid document but "x" is not.

This is the same problem pointed out for YAML 1.2 spec, first by 
Joshua Choi,

http://sourceforge.net/mailarchive/forum.php?thread_name=200e06280904252219i1da33755h200bdac14058ba36%40mail.gmail.com&forum_name=yaml-core

and then by me.

http://sourceforge.net/mailarchive/forum.php?thread_name=1254356424.5043.224.camel%40nero&forum_name=yaml-core

Probably, most of the real implementations ignore the spec 
to be compatible with hand-written documents possibly without 
a line break at the end. But, at least, a YAML serializer 
should not output a YAML document without a line break at the 
end.

Best,
Osamu Takeuchi


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