Re: string literal following by colon-style call?

[Lorenzo Donati <lorenzodonatibz@...>]

On 10/08/2013 9.42, Hao Wu wrote:
> 
> 
> 
> On Sat, Aug 10, 2013 at 12:35 AM, Tim Hill <drtimhill@gmail.com
> <mailto:drtimhill@gmail.com>> wrote:
> 
> 
>     On Aug 10, 2013, at 12:31 AM, Tim Hill <drtimhill@gmail.com
>     <mailto:drtimhill@gmail.com>> wrote:
> 
>>
>>     On Aug 9, 2013, at 11:58 PM, Hao Wu <wuhao.wise@gmail.com
>>     <mailto:wuhao.wise@gmail.com>> wrote:
>>
>>>
>>>     So my question is, when dealing with string literal, why couldn't
>>>     we just say:
>>>
>>>     "a string literal":lower()
>>>
>>>     instead
>>>
>>>     ("a string literal"):lower()
>>>
>>>     Is there a language reason to prevent this?
>>>
>>>     Thanks,
>>>
>>>     ~hao
>>
>>     What's more interesting is that, by my reading of the BNF,
>>     _neither_ of these should work (though the second, as you state,
>>     does work). SO far as I can see, the BNF doesn't describe the full
>>     colon syntax (it is only mentioned when used as part of a function
>>     declaration).
>>
>>     --Tim
>>
> 
>     Ignore that .. my brain shut down there for a moment. Here is the
>     Lua BNF that is significant:
> 
>     prefixexp ::= var | functioncall | ‘(’ exp ‘)’ functioncall ::=
>     prefixexp args | prefixexp ‘:’ Name args 
> 
>     So yes, you do need parens.
> 
> 
> Yes, I was about to say that. 
> 
> It certainly shouldn't be a "BNF" issue or "parser" issue that wouldn't
> accept the first form (or maybe it is? the parser would take more
> memory? but we also have byte-code...) - this made me wonder why and the
> real reason behind it
>  
> 
>     --Tim
> 
> 
> 
> 
> ~hao
There have been already discussions on this (check old posts ~ 2 years
ago if my memory isn't failing me).

IIRC the parens are needed to avoid some ambiguity in parsing.


-- Lorenzo

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