[netmod] whitespace stripping

[Ladislav Lhotka <[e-mail]>]

Hi,

YANG has this peculiar rule for double-quoted strings:

   If the double-quoted string contains a line break followed by space
   or tab characters that are used to indent the text according to the
   layout in the YANG file, this leading whitespace is stripped from the
   string, up to and including the column of the double quote character,
   or to the first non-whitespace character, whichever occurs first.  In
   this process, a tab character is treated as 8 space characters.

As I recently found out, this kind of whitespace stripping is difficult to implement with some standard parser libraries because the parser has to be able to get the column of the opening double quote. And even if it is possible, it slows down parsing.

The existing practice shows such multi-line strings are only used in descriptions and references where whitespace stripping is not needed at all - e.g., for translation to YIN format such strings have to be re-formatted anyway. In all other cases it is IMO much better to use concatenation

  "..."
+ "..."

So I’d suggest to remove whitespace stripping in YANG 1.1, for the benefit of parsers and the spec itself.

Lada

--
Ladislav Lhotka, CZ.NIC Labs
PGP Key ID: E74E8C0C