[elephant-devel] Storing objects in the root when don't care about the key

[Robert L. Read]

On Sun, 2007-05-27 at 16:23 -0400, Joubert Nel wrote:

> Hi -
> 
> I have a persistent class (i.e. :metaclass persistent-metaclass) defined
> and am adding a whole bunch of objects that are instances of this class
> to the root of my Elephant store.
> 
> In order to retrieve a list of them I do:
> 	(map-class fn 'my-class-name)
> 
> 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.

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.


> 
> I'm doing this to avoid overhead in generating more esoteric unique keys
> such as UUID's. 
> 
> Are there any reasons why I should NOT use OID as the key? 
> 
> Joubert
> 
> 
> 
> 
> 
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