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digitalmars.dip.ideas - `__CONTEXT__` special token

the special token sequence acts like other but is lowered to 
`mixin("context")`

```d
int context=0;
int counter(ref int i=__CONTEXT__)=>++i;

unittest{
   assert(counter==1);
   assert(counter==2);
}

unittest{
   float context;
   //assert(counter==3);//Error counter(float) doesnt exist. using 
existing type safety contexts wouldnt get confused
}

unittest{
   int i;
   assert(counter(i)==1);//by overwriting the default argument it 
trivially replaceable by being explict
   assert(counter(i)==2);
}
```

https://forum.dlang.org/thread/rpqppcvebeblghmrcyjj forum.dlang.org
Dec 22 2025