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

[Thomas 'PointedEars' Lahn]

Ian Kelly wrote:

> […] Thomas 'PointedEars' Lahn […] wrote:
>> Ian Kelly wrote:
>>> What I mean is that if you construct a parse tree of "foo" "bar" using
>>> that grammar, it looks like this:
>>>
>>>      expr
>>>        |
>>>     STRING+
>>>      /   \
>>> STRING  STRING
>>> […]
>>>
>>> There is only one expr node, and it contains both STRING tokens.
>> Prove it.
> 
> I'm not going to expend the effort that would be required to go
> through the entire Python grammar step-by-step and exhaustively prove
> that "foo" "bar" can unambiguously only be produced as a single expr.

And why should you?  That is not what you claimed.

> If you believe otherwise, show a parse tree that parses these as
> separate expressions.

Fallacies: Straw man, shifting the burden of proof.

>> But be warned: Neither would prove that a string literal is not an
>> expression.
> 
> I've not claimed that a string literal is not an expression.

Yes, you did.  You debated my statement which says that.  Let me refresh 
your memory.  I said:

| As I showed, string literals and consecutive tokens of string literals 
| (“STRING+”) so as to do implicit concatenation *are* expressions of the 
| Python grammar.

To which you replied:

| What the grammar that you quoted from shows is that STRING+ is an
| expression. The individual STRINGs of a STRING+ are not expressions, […]
                             ^^^^^^^              ^^^^^^^^^^^^^^^^^^^
You continued with

| except to the extent that they can be parsed in isolation as a STRING+.

but that is nothing more than a backdoor, contradictory to what you said 
before (and, as it has been showed, nonsensical).

> My claim is that a literal consisting of the implicit concatenation of 
> more than one string token is can only be parsed as one expression, not
> several.

Then you must have fundamentally misunderstood my statement and this whole 
discussion.

> Parsing "foo" "bar"
> 
>>  Because you did not consider the most simple variant of an AST
>> (or subtree) according to this grammar:
>>
>>     expr
>>      |
>>    STRING
> 
> Of course I did. This is again *exactly* what I was talking about in
> reference to parsing the individual strings in isolation.

Actually, you were arguing against my statement that string literals are 
expressions (that a string literal is an expression).  You claimed, rather 
explicitly, that they were not.  See above.

>> Again, “STRING+” does _not_ mean “STRING STRING STRING*”; it means
>> “STRING STRING*”.  The second and following STRINGs are *optional*.
> 
> Please stop speaking down to me.

I am not speaking down to you.  But the fact needed to be emphasized that 
you could not have been reading carefully what I wrote.

> I'm quite familiar with basic concepts of EBNF.

But apparently not logic.

-- 
PointedEars

Twitter: @PointedEars2
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