dmd 1.046 and 2.031 releases

[Michel Fortin]

On 2009-07-07 01:12:12 -0400, Andrei Alexandrescu 
<SeeWebsiteForEmail at erdani.org> said:

> Nick Sabalausky wrote:
>> Those examples are all cases where the meaning and context are wildly 
>> different fbetween one use and the other. But with '..', both uses are 
>> very similar: "From xxx to (incl/excl) yyy". Big differences are ok, 
>> they stand out as obvious. Small differences can be more problematic.
> 
> You'd have an uphill battle using a counterfeit Swiss army knife 
> against a battery of Gatling guns



> arguing that
> 
> case 'a': .. case 'z':
> 
> is very similar with
> 
> 0 .. 10
> 
> That's actually much more different than e.g.
> 
> a = b * c;
> 
> versus
> 
> b * c;

They aren't so much different if you consider "case 'a':" and "case 
'z':" as two items joined by a "..", which I believe is the expected 
way to read it. In the first case "case 'a':" and "case 'z':" joined by 
a ".." means an inclusive range, in the second case "0" and "10" joined 
by a ".." means an exclusive one.

With "b * c", the meaning is completly different depending on whether b 
is a type or not. If "b" is a type, you can't reasonabily expect "b * 
c" to do a multiplication and you'll get an error about it if that's 
what you're trying to do. Wheras with "case 'a': .. case 'b':" you can 
reasonably expect an exclusive range if you aren't too familiar with 
the syntax (and that's a resonable expectation if you know about 
ranges), and you won't get an error of you mix things up; thus, clarity 
of the syntax becomes more important.

I still think that having that syntax is better than nothing, but I do 
believe it's an inconsistency and that it may looks ambiguous to 
someone unfamiliar with it.

But my worse grief about that new feature is the restriction about 256 
values which is pretty limitating if you're writing a parser dealing 
with ranges of unicode characters. I guess I'll have to continue using 
ifs for that.


-- 
Michel Fortin
michel.fortin at michelf.com
http://michelf.com/