• Philip Daniels (8/8) Aug 23 2012 auto x = [1,2,3];
• Jonathan M Davis (9/20) Aug 23 2012 It's the same thing that slicing does. The result is tail-const. And sin...
• Philip Daniels (4/29) Aug 23 2012 Thanks for the explanation Jonathan. Another thing to add to me

"Philip Daniels" <foo foo.com> writes:

auto x = [1,2,3];
auto y = x.idup;
y ~= 99;   // fine!
y[0] = 99; // "Error: y[0] isn't mutable"
y.clear;   // fine!


So idup is returning an "immutable(int)[]" rather than an 
"immutable int[]".

I find this a bit surprising. Anybody else?

"Jonathan M Davis" <jmdavisProg gmx.com> writes:

On Thursday, August 23, 2012 23:55:10 Philip Daniels wrote:
 auto x = [1,2,3];
 auto y = x.idup;
 y ~= 99; // fine!
 y[0] = 99; // "Error: y[0] isn't mutable"
 y.clear; // fine!
 
 
 So idup is returning an "immutable(int)[]" rather than an
 "immutable int[]".
 
 I find this a bit surprising. Anybody else?

It's the same thing that slicing does. The result is tail-const. And since you 
can assign it to immutable int[] if you want to, it's more flexible this way. 
It just means that auto gives you a mutable array with immutable elements 
rather than an immutable array. And if you don't want to care what the type is 
but still want it to be full immutable, then just use immutable rather than 
auto:

immutable y = x.idup;

- Jonathan M Davis

"Philip Daniels" <foo foo.com> writes:

On Thursday, 23 August 2012 at 22:03:04 UTC, Jonathan M Davis 
wrote:
 On Thursday, August 23, 2012 23:55:10 Philip Daniels wrote:
 auto x = [1,2,3];
 auto y = x.idup;
 y ~= 99; // fine!
 y[0] = 99; // "Error: y[0] isn't mutable"
 y.clear; // fine!
 
 
 So idup is returning an "immutable(int)[]" rather than an
 "immutable int[]".
 
 I find this a bit surprising. Anybody else?

 It's the same thing that slicing does. The result is 
 tail-const. And since you
 can assign it to immutable int[] if you want to, it's more 
 flexible this way.
 It just means that auto gives you a mutable array with 
 immutable elements
 rather than an immutable array. And if you don't want to care 
 what the type is
 but still want it to be full immutable, then just use immutable 
 rather than
 auto:

 immutable y = x.idup;

 - Jonathan M Davis

Thanks for the explanation Jonathan. Another thing to add to me 
cheat sheet of D-isms :-)