immutable singleton pattern with static opCall

[Justin Johansson]

Steven Schveighoffer wrote:
> On Mon, 28 Jun 2010 08:40:36 -0400, Justin Johansson <no at spam.com> wrote:
> 
>> Steven Schveighoffer wrote:
>>> On Mon, 28 Jun 2010 08:07:40 -0400, Justin Johansson <no at spam.com> 
>>> wrote:
>>>
>>>> Steven Schveighoffer wrote:
>>> To go one step further, if you want it to truly be a singleton type, 
>>> you should mark the constructor private.
>>>  -Steve
>>
>> Indeed.  I forgot the private constructor in this version but had it
>> in earlier versions.
>>
>> Continuing on with the saga, it's a pity that immutable
>> is not compatible with Object toString method without a cast.
>>
>> class Foo
>> {
>>     static immutable private Foo instance;
>>
>>     static this() {
>>        instance = new Foo;
>>     }
>>
>>     static immutable(Foo) opCall() {
>>       return instance;
>>     }
>>
>> immutable:
>>    private this() {}
>> }
>>
>>
>> void main()
>> {
>>     // numerous compile errors if the cast is left out
>>     stdout.writefln( "Foo() = %s", cast(Foo) Foo());
>> }
> 
> That's because toString should be a const function.
> 
> See http://d.puremagic.com/issues/show_bug.cgi?id=1824
> 
> please vote for the bug.
> 
> -Steve

That's a pretty fundamental oversight.

just signed up new account (procode == me) and voted for the bug

JJ