Re: string:sub

[spir <denis.spir@...>]

On Sat, 06 Mar 2010 11:29:25 +1100
David Burgess <dabsoft@gmail.com> wrote:

> It seems to me that negative values of string.sub() are inconsistent 
> with not only the first parameter but also with string.find().
> 
> Examples:
> 
>  >s="123456789"
>  >=s:sub(-1)
> 9
>  >=s:sub(1,0)
> 
>  >=s:sub(1,-1)
> 123456789
>  >=s:sub(1,-2)
> 12345678
>  >=s:find("56")
> 5	6
>  >=s:sub(1,6-2)
> 1234
>  >=s:sub(-1)
> 9
> 
> I am boldly suggesting that the second parameter with negative indices 
> behave the same as the first.

That's what id does. (Unlike eg in python.) What do you mean?

> I guess this implies that the value 0 for
> the second parameter would return the length of the string.

So you wish to break the symetry between positive and negative indices?
This may make sense for half-open interval, where in fact s.sub(i,j) == s[i,j[.

> Maybe I have used too many similar functions in other languages but -1 
> meaning the last character seems intuitive to me.

-1 precisely points to the last character. s.sub(-1) == s.sub(#s)

So, what's wrong? (These points precisely are Lua features I'm very happy with :-)

Denis
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