Implementing typestate

[Freddy via Digitalmars-d]

On Tuesday, 15 September 2015 at 17:45:45 UTC, Freddy wrote:
> ...

I just thought of some corner cases and how to solve them.
---
Disallow global variable with typestate (there might be a better 
solution down the line).
The evaluated typestate of variables after going through  
branches (if,for,etc...) must be the same.
Example
---
void func(){
     File f;
     if(someVar){
         f.openWrite("a.txt");
     }
     //error here one branch where f is none, another branch where 
f is open
}
---