How do "pure" member functions work?

[Sean Eskapp]

== Quote from David Nadlinger (see at klickverbot.at)'s article
> On 8/20/11 5:13 PM, Sean Eskapp wrote:
> > Does marking a member function as pure mean that it will return the same
> > result given the same parameters, or that it will give the same result, given
> > the same parameters and given the same class/struct members?
> The second one, the implicit this parameter is just considered a normal
> argument as far as purity is concerned.
> David

Wait, references and pointers are now valid for pure function arguments?