dmd 1.046 and 2.031 releases

[Andrei Alexandrescu]

Derek Parnell wrote:
>  Because
>  
>  1.	case X..Y:
>  
>  looks like
>  
>  2.	foreach(e; X..Y)
>  3.	array[X..Y]
>  4.     case X:..caseY:
> 
> 
>  yet the X..Y has a VERY DIFFERENT meaning. (1) is inclusive of Y, and 
>  (2) and (3) are exclusive of Y, and (4) is inclusive of Y ... oh, hang
> on...
> 
> Sorry, but I'm just not getting the "VERY DIFFERENT" part yet. Right now, D
> has ".." meaning exclude-end value (2. and 3.) AND it also has ".." meaning
> include-end value (4.), depending on context. 

I think here's the point where our thinking diverges. You say ".." has a 
meaning. No. It does not have any meaning. It's punctuation. Same way, 
"*", "&", ":", ",", etc. have no meaning in D all alone. They are 
tokens. They acquire a meaning by partaking in grammatical constructs.

What does have arguably a meaning is "expression1 .. expression2". (Even 
that could be debatable because it's not a standalone expression). But 
anyway, the meaning that "expression1 .. expression2" acquires in array 
slices and foreach statements is uniform.

Now we have the different construct "case expression1: .. case 
expression2:" That is evidently not "expression1 .. expression2", does 
not include it as a part, and shares essentially nothing except the ".." 
with it. That's my point.

> Ok, I admit that there is one subtle difference. Examples 2 and 3 are of
> the form 
> 
>   IntExpression .. IntExpression
> 
> and example 4 is 
> 
>   CaseLabelInt .. CaseLabelInt
> 
> but seriously, people are not going to notice that. We see double-dot and
> think "range". 

You should see "expression1 .. expression2" and think "range". There's 
very few tokens that make one think of only one thing when seeing them. 
One of them is "%" - makes one think of modulus, another is "^" meaning 
xor, another is "$" - array size... but that's about it.

> I know that this is not ever going to be changed so I'm not arguing that it
> should. 
> 
> (One of the most frequent bugs I have in my D programs is that I forget
> that X..Y excludes Y because it's not natural to me to see text that looks
> like "the range X to Y" but means "the range X to Y-1".)
> 
> It seems that D would benefit from having a standard syntax format for
> expressing various range sets;
>  a. Include begin Include end, i.e. []
>  b. Include begin Exclude end, i.e. [)
>  c. Exclude begin Include end, i.e. (]
>  d. Exclude begin Exclude end, i.e. ()

I'm afraid this would majorly mess with pairing of parens.


Andrei