Const foreach

[Pelle Månsson]

On 11/22/2010 04:12 PM, Simen kjaeraas wrote:
> spir <denis.spir at gmail.com> wrote:
>
>> On Sun, 21 Nov 2010 20:21:14 -0500
>> bearophile <bearophileHUGS at lycos.com> wrote:
>>
>>> If in a D2 program I have an array of mutable items I may want to
>>> iterate on them but not modify them, so I'd like the iteration
>>> variable to be const. This is possible, but it seems I lose type
>>> inference:
>>>
>>>
>>> void main() {
>>> int[3] array; // not const
>>> // foreach (const x; array) {} // Error
>>> // foreach (const auto x; array) {} // Error
>>> // foreach (const(int) x; array) {} // OK
>>> foreach (const(typeof(array[0])) x; array) {} // OK
>>> }
>>>
>>>
>>> Is something wrong in that code? Is this a known limitation, an
>>> inevitable one? Is this an enhancement request worth adding to Bugzilla?
>>>
>>> Bye and thank you,
>>> bearophile
>>
>> Maybe you'll find it weird, but I would expect
>> foreach (const(auto) x; array) {};
>> to be the logical idiom for this. "auto" beeing a kind of placeholder
>> for a type name.
>
> 'auto' is not a placeholder for a type, but the default storage class.
> IOW, 'int n;' == 'auto int n;'. This does however not compile,
> complaining that it has no effect.
>
> Specifying just the storage class signals the compiler to use type
> inference. Try it:
>
> const x = 4;
> immutable y = 4;
>

I'm not sure you are correct:

     const static auto x = 4;