TryElseExpression DIP

[pineapple via Digitalmars-d]

I was writing some code and realized D doesn't have an equivalent 
to Python's `else` for error handling, and I think we should 
change that

https://github.com/dlang/DIPs/pull/43/files



In Python, the try/catch/finally syntax is augmented with an 
additional clause,
termed else. It is a fantastically useful addition to the 
conventional syntax.
It works like this:

     try:
         do_something()
     except Exception as e:
         pass # Runs when an error inheriting from Exception was 
raised
     else:
         pass # Runs when no error was raised
     finally:
         pass # Runs unconditionally, evaluates last

Imitating this functionality in D,

     try{
         do_a_thing();
     }catch(Exception exception){
         handle_error();
     }else{
         depends_on_success_of_thing();
     }finally{
         do_this_always();
     }

Would be equivalent to

     bool success = false;
     try{
         do_a_thing();
         success = true;
     }catch(Exception exception){
         handle_error();
     }finally{
         try{
             if(success){
                 depends_on_success_of_thing();
             }
         }finally{
             do_this_always();
         }
     }