"Alf P. Steinbach" <al...@start.no> wrote: > A copyable reference is a pointer. That is, a "pointer", in e.g. the > Java sense, > and in the general language independent sense, means a copyable > reference -- as illustrated e.g. in the Stanford computer science > 101 course page I > referred you to earlier, with C versus Java pointers illustrated in > the concrete.
The fact that C style pointers are used internally is an detail of the CPython implementation. In CPython objects once created remain in the same memory location (and their id is their address). Compare that to IronPython where the objects themselves can move around in memory so they have no fixed address. Try comparing the IronPython implementation to C pointers and you'll cause a lot of confusion. e.g. someone might think the id() value is in some way related to an address. Ruby implements integers without using any pointers at all: there's nothing in the Python specification which prevents a Python implementation doing the same for small integers, in fact I believe it has been tried but wasn't found to improve performance. The terminology of 'objects', 'names', 'references' describes an abstract machine. The Python runtime can implement it in any way it chooses so long as those semantics are preserved. One implementation involves 'pointers', but that word implies other baggage which is not a required part of the model. -- Duncan Booth http://kupuguy.blogspot.com -- http://mail.python.org/mailman/listinfo/python-list
