What are the differences between these forms of function-like declarations ?

[Anderel Cerol]

>
> a real example is :
> ....
> import std.net.curl;
> auto http=HTTP();
> ...
> http.onReceiveStatusLine(...);
> ...
>
> the function http.onReceiveStatusLine(...) is exactly what the 
> function on(...) is above.
> The environment is dmd 2.060 Windows.
plus, what passes to the http.onReceiveStatusLine is just 
(a){a.writeln();} with different forms above.