[elephant-devel] Storing objects in the root when don't care about the key / add same key to root more than once

[Joubert Nel]

On Sun, 2007-05-27 at 23:46, Robert L. Read wrote:
> On Sun, 2007-05-27 at 16:23 -0400, Joubert Nel wrote: 

<snip>

> > My question is:
> > Currently I'm using the OID of the object as its key when I
> > (add-to-root) because this is the only slot in my class that is
> > guaranteed to be unique. (from a use-case point of view I don't care
> > what the key is).
> I'm afraid this may betray a lack of clarity in the documentation.  If
> you are using a persistent-metclass,
> you probably DON'T want to call add-to-root on it.

Thanks for your note, Robert.

You're right; the examples in the documentation seem to imply that it is
usual to (add-to-root), even for persistent classes (e.g. example code
on p.41).

> 
> In general, if you are using Ian's persistent classes, there is no
> reason to explicitly call add-to-root----
> I think you will find that "map-class" above let's you get to every
> class instance quite easily without
> calling add-to-root.
> 
> The act calling "make-instance" on such a class is sufficient to place
> the instance in the DB, I think.

Thanks for confirming - I suspected as much and am now no longer doing
an add-to-root of persistent objects.

On another note:
In my experimentation I added several objects to the root, all with the
same key. 
All these objects get added but there is the following curiosity:
- I can do a map-class to get them all, BUT
- map-root will only return one key/value pair for a given key (even
when there are multiple objects stored against the same key)

I'm wondering whether a design decision was  made to allow addition of
the same key more than once? 

Thanks for a great library.

Joubert