Terminology: “reference” versus “pointer”
random832 at fastmail.com
Sat Sep 12 06:42:04 CEST 2015
Ben Finney <ben+python at benfinney.id.au> writes:
> With the significant difference that “pointer” implies that it has its
> own value accessible directly by the running program, such as a pointer
> in C.
Its own value *is* what you're accessing when you assign or return
it. You just can't do math on it, but there are lots of things you can't
do math on.
> That's different from a “reference”, which to my understanding implies
> the running program does *not* normally have direct access to it as a
> distinct value. The only way you can use a reference is to get at the
> object to which it refers.
In C++, references cannot be reassigned. I consider *that* the
fundamental difference - a pointer is a variable that you can reassign
and return; a reference always refers to the same object once created.
> That's the distinction I've been reying on for years, anyway: Python's
> names are references, collections are collections of references, etc.
> They aren't pointers because you can't get them as a distinct value; you
> can only use them to refer to the object at the other end.
Anyway, maybe we do need a term to distinguish Python/C#/Java pointers
from C/C++ pointers - maybe call it a "non-arithmetic" pointer, since
the key thing about it is you can't do pointer arithmetic on them to get
the object "next to" the one it points at.
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