Modify Object Pointer during Initialzation

[Jeroen Bollen]

This topic is somewhat related to this question I asked yesterday 
on StackOverflow: http://stackoverflow.com/q/22921395/2558778

Basically, why is this its own variable? Why doesn't D simply use 
the variable it was called with?

https://gist.github.com/Binero/10128826

I don't see why this needs to be a new variable and cannot simply 
be 'passed-by-reference'.