• bearophile (13/13) Jan 13 2014 Code like this doesn't compile, the swap doesn't work:
• Jesse Phillips (4/17) Jan 13 2014 I thought it was to provide an index number during a foreach
• bearophile (5/9) Jan 13 2014 But "source" is immutable, so its elements aren't assignable.

"bearophile" <bearophileHUGS lycos.com> writes:

Code like this doesn't compile, the swap doesn't work:


import std.range: indexed;
import std.algorithm: swap;
void main() {
     immutable source = [10, 20, 30];
     auto ind = indexed(source, [0, 1, 2]);
     swap(ind[0], ind[1]);
}


But isn't an important usage case of indexed() to shuffle and 
sort a view of an immutable array, like sorting a 
immutable(int)*[] ?

Bye,
bearophile

"Jesse Phillips" <Jesse.K.Phillips+D gmail.com> writes:

On Tuesday, 14 January 2014 at 01:14:41 UTC, bearophile wrote:
 Code like this doesn't compile, the swap doesn't work:


 import std.range: indexed;
 import std.algorithm: swap;
 void main() {
     immutable source = [10, 20, 30];
     auto ind = indexed(source, [0, 1, 2]);
     swap(ind[0], ind[1]);
 }


 But isn't an important usage case of indexed() to shuffle and 
 sort a view of an immutable array, like sorting a 
 immutable(int)*[] ?

 Bye,
 bearophile

I thought it was to provide an index number during a foreach 
iteration. If you have an randomAccess range with assignable 
elements, why use indexed?

"bearophile" <bearophileHUGS lycos.com> writes:

Jesse Phillips:

 I thought it was to provide an index number during a foreach 
 iteration.

That's the enumerate() range, that is still missing in Phobos.


 If you have an randomAccess range with assignable elements, why 
 use indexed?

But "source" is immutable, so its elements aren't assignable.

Bye,
bearophile