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();
        }
    }