A simple single line, triple-quoted comment is giving syntax error. Why?

[Thomas 'PointedEars' Lahn]

Dave Angel wrote:

[Fixed quotation]

> On 03/26/2015 01:09 AM, Ian Kelly wrote:
>>>>> Thomas 'PointedEars' Lahn wrote:
>>>>>> <https://docs.python.org/3/reference/lexical_analysis.html#string->>>>>> literal-concatenation>
>>
>> What the grammar that you quoted from shows is that STRING+ is an
>> expression. The individual STRINGs of a STRING+ are not expressions,
>> except to the extent that they can be parsed in isolation as a
>> STRING+. By the same token, a STRING+ is a single string literal, not
>> an aggregate of several.
> 
> That's the way I also read the BNF.

Then I am afraid you need to refresh your knowledge of formal grammars.

> But something I cannot find in that chapter of the reference is the
> definition of STRING+

You *definitely* need to refresh your knowledge of formal grammars.

“STRING+” in this flavor of _E_BNF is – rather obviously – equivalent to

  <multiple-string> ::= <STRING> <STRING>*
  <STRING>          ::= '"' <no-unescaped-doublequote>* '"'
                      | "'" <no-unescaped-singlequote>* "'"
                      | '"""' <no-triple-doublequote>* '"""'
                      | "'''" <no-triple-singlequote>* "'''"

in BNF and

  multiple-string = STRING *STRING
  STRING          = '"' *no-unescaped-doublequote '"'
                  / "'" *no-unescaped-singlequote '"'
                  / '"""' *no-unescaped-triple-doublequote '"""'
                  / "'''" *no-unescaped-triple-singlequote "'''"

in ABNF.  I suspect that in this flavor of EBNF the definition of STRING 
looks similar to the following:

  STRING: ('"' no_unescaped_doublequote* '"'
         | "'" no_unescaped_singlequote* "'"
         | '"""' no_unescaped_triple_doublequote* '"""'
         | "'''" no_unescaped_triple_singlequote* "'''")

Definition of the still undefined goal symbols is left as an exercise to the 
reader.

-- 
PointedEars

Twitter: @PointedEars2
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