From: Robert Klemme <shortcutter@...>
Date: 2011-10-11T23:50:06+09:00
Subject: Re: why does `a + f b` not parse?

On Tue, Oct 11, 2011 at 4:33 PM, Phillip Gawlowski
<cmdjackryan@gmail.com> wrote:
> Don't top post, please.
>
> 2011/10/11 Bartosz Dziewoński <matma.rex@gmail.com>:
>> Yes, I think we all know that; the question is, why does 2 + sqrt(5)
>> parse, but 2 + sqrt 5 does not? I've been wondering this myself - is
>> that syntax somehow ambiguous?
>
> So, which one shall it be?
>
>  2.+.sqrt(5)
>  2.+(sqrt(5))
>  2.+.sqrt.5
>  2.+(sqrt.5)
>  2.+(sqrt(5))

I believe the versions which turn a space into a dot are not valid
candidates.  Or is there any place other than for operators where this
happens in Ruby?  I mean "a b" can never by "a.b" but must always be
"a(b)".  That leaves only "2.+(sqrt(5))" on your list (item 2, same as
item 5).

It's the same with ordinary methods:

$ ruby19 -ce '1 + f 2'
-e:1: syntax error, unexpected tINTEGER, expecting keyword_do or '{' or '('

$ ruby19 -ce 'a.b c, d e'
-e:1: syntax error, unexpected tIDENTIFIER, expecting keyword_do or '{' or '('
$ ruby19 -ce 'a.b c, d(e)'
Syntax OK

$ ruby19 -ce 'a b, c d'
-e:1: syntax error, unexpected tIDENTIFIER, expecting keyword_do or '{' or '('
$ ruby19 -ce 'a b, c(d)'
Syntax OK
16:48:16 oz-56838-negative-session-count$ ruby19 -ce 'a.b c, d do end'
Syntax OK

I think as soon as the comma is missing the end of the argument list
or a nested argument list is expected by the parser (which is also
indicated by the error message).

Kind regards

robert

-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/