Performance penalty for using ranges

[monarch_dodra]

On Sunday, 25 August 2013 at 18:13:39 UTC, Joseph Rushton 
Wakeling wrote:
> On 25/08/13 20:07, Paul Jurczak wrote:
>> What is the purpose of "immutable _;" above? Why not "i;"?
>
> It's never used, so notating it like this means you'll never 
> clash with another variable name by accident (e.g. if somewhere 
> else in the function you declare an int i).
>
> Had never thought of that before but it's a handy trick, I'll 
> have to make use of it in my own code ...

It never clashes untill you nest two foreach, and then you have 
to use __ ...

foreach( _ ; 0 .. M)
     foreach( __ ; 0 .. N)
         ...

I have an enhancement request to simply allow anonymous iteration:
foreach( ; 0 .. N)

http://d.puremagic.com/issues/show_bug.cgi?id=9009