Re: EOF Design Questions

Hi Francis,

Thanks for your posting.

On 08/04/2004, at 10:38 PM, Francis Labrie wrote:
> You can define an abstract superclass (i.e. ClonableGenericRecord) for 
> all your cloneable entities extending EOGenericRecord Cloneable with a 
> method that does something like this:
>
> 	public EOEnterpriseObject clone() {
> 		Enumeration keys;
> 		EOEnterpriseObject object;
> 		Object value;
> 		String key;
>
> 		object = 
> EOClassDescription.classDescriptionForEntityName(entityName()).
> 			createInstanceWithEditingContext(editingContext(), null);
>
> 		keys = allPropertyKeys().objectEnumerator();
> 		while(keys.hasMoreElements()) {
> 			key = (String)keys.nextElement();
> 			object.takeValueForKey(valueForKey(key));
> 		} // while
>
> 		return(object);
> 	} // clone

That's a clear and straight-forward way of doing it.

I was hoping, however, that there maybe a more efficient way of doing 
it (that may need to be provided by the frameworks using underlying 
data structures).

> But this clone the targeted entity only, i.e. all relationships will 
> be same for both the original and the cloned entity:
>
> 	EOA.toEOB -> clone -> EOA'.toEOB
>
> If you want to clone entities in relationships as well like this:
>
> 	EOA.toEOB -> clone -> EOA'.toEOB'
>
> Then you'll have to modify the clone() loop to build one for each 
> attributeKeys(), toOneRelationshipKeys() and toManyRelationshipKeys() 
> instead of using allPropertyKeys().

Yes, that will depend upon whether I need a shallow or deep clone.

>> 2.  How best to revert some EOs (but not all) in the EC?
>> Using the original snapshot ... but could that change (is that a 
>> problem)?
>
> You can use the editing context revert() method.  Setting up the 
> original snapshot shouldn't be a problem though.

Ok, but that will revert all objects in the editing context.

I want to revert only those objects that have been changed (and thus 
cloned).

For example, I don't want to revert the cloned objects.

Cheers,
Ashley.

--
Ashley Aitken
Perth, Western Australia
mrhatken at mac dot com