immutable and static this()

[Jonathan M Davis]

> On Mon, 21 Mar 2011 22:27:17 +0100, teo <teo.ubuntu at yahoo.com> wrote:
> > I cannot initialize immutable class members inside a static this()
> > constructor. Is there any reason for that?
> > 
> > Example:
> > class Test
> > {
> > 
> >     public immutable(int) x;
> >     static this()
> >     {
> >     
> >         x = 1; // Error: variable Test.x can only initialize const x
> > 
> > inside constructor
> > 
> >     }
> > 
> > }
> 
> Non-static class members require a this pointer, and thus cannot be
> initialized in a static constructor. However, if that is the error
> message you get, it is clearly misleading.

No. Error message is essentially correct, just confusing. In this case, x is a 
member variable, _not_ a class/static variable. So, it must either be directly 
initialized

public immutable int x = 1;

or in a constructor (and in this case the constructor would have to be 
immutable).

public immutable int x;

this() immutable
{
    int x = 1;
}

static this() in a class is for initializing class/static variables only, so 
if you did

public static immutable int x;

static this()
{
    int x = 1;
}

that would work. The fact that it is immutable has nothing to do with whether 
it is a member variable or a class/static variable, so it has no effect on 
whether a normal or static constructor is used.

- Jonathan M Davis