Question regarding D v.0110

[Steven Schveighoffer]

On 7/13/20 3:45 AM, Remi wrote:
> Thanks for the suggestions regarding the cyclic dependency, I figured 
> out a way to remove the cycles. It was mostly doing this in each class:
> 
>> class Foo
>> {
>>     static Rand rand;
>>     public static this()
>>     {
>>         rand = new Rand;
>>     }
>>     public static void setRandSeed(long n)
>>     {
>>         rand.setSeed(n);
>>     }
>> }
> 
> which I replaced with
> 
>> class Foo
>> {
>>     static Rand rand;
>>     public static void setRandSeed(long n)
>>     {
>>         if (!rand)
>>         {
>>             rand = new Rand;
>>         }
>>         rand.setSeed(n);
>>     }
>> }
> 
> Simple and it works!

This is slightly different. In the first case, rand is initialized even 
if you don't call setRandSeed. A more correct approach:

public static Rand rand()
{
    static Rand result;
    if(result is null)
        result = new Rand;
    return result;
}

Though it depends on usage -- perhaps a Rand is useless without a seed set?

As I suspected, the static ctor could easily be marked standalone (as 
in, it can't be part of a cycle, because it doesn't depend on any other 
module to run). This is quite frequently one of the biggest problems 
with D's static ctors.

-Steve