Sniff, was Re: [ZODB-Dev] Copying instances between multiple storages

[Toby Dickenson]

On Tue, 21 May 2002 08:55:01 -0300, Christian Reis <kiko@async.com.br>
wrote:

>On Tue, May 21, 2002 at 11:02:03AM +0100, Toby Dickenson wrote:
>> On Mon, 20 May 2002 18:50:36 -0300, Christian Reis <kiko@async.com.br>
>> wrote:
>>=20
>> >> Fair enough. So what do I have to do? Instance another object and =
copy
>> >> it's data over (ugh)?
>>=20
>> Thats what I would do, if your object is of small finite size.
>
>Really? There is no clone functionality in the ZODB?

Sure, there is the export/import I mentioned later in my post. I still
wouldnt use it if my objects were small.

> I've noticed that
>something has been mentioned called Mount*Storage; I'd suppose it'd do
>something like that, but I haven't seen it yet.

No, it works very differently. It integrates two different object
database at the zope application layer, not at object layer.

>So you suggest I just create a new instance, and iterate through the
>attributes, copying them over.

Thats what I would do if the objects are small.

>>>> import copy
>>>> p =3D get_catalog("Products").dump()[0]
>>>> copy.copy(p)
>Traceback (most recent call last):
>  File "<stdin>", line 1, in ?
>  File "/usr/local/lib/python2.1/copy.py", line 78, in copy
>    raise error, \
>copy.Error: un(shallow)copyable object of type <extension class
>Domain.Product.Product at 83ccba8>

Aha, yes. it doesnt know how to automatically copy extension classes.

You might want to try hacking the copy module so that it uses the
_copy_int function for extension class instances as well as ordinary
functions.  I dont see why that shouldnt work (but Ive been known to
be wrong in making statements like that ;-)

>And deepcopy provides me the same error, so I probably have to define
>__*copy__ if it is to work, right?

Yes.=20

>Yes, addressing is another problem, but it doesn't invalidate the
>problems with cloning objects, since I have to support disconnected
>operation (that's the gist of it, actually - I need to copy objects
>between databases).

have you considered a solution at a lower layer; rsync Data.fs ?

Toby Dickenson
tdickenson@geminidataloggers.com