15 Jan
2010
15 Jan
'10
2:42 p.m.
Hi Anca,
On Jan 13, 2010, at 1:42 PM, Anca Luca wrote:
Hi devs,
Short story:
1/ add the CLASS, OBJECT, PROPERTY EntityTypes in the model
+1
2/ serialization for referencing a property of an object
a) wiki:Space.Page^className[objectNumber]#property
b) wiki:Space.Page^className#objectNumber$property
+0.75 for b)
Long story:
1/ I would need to extend the EntityReference to be able to target a
property in an object in a document.
For this, I will need to add
/**
* Represents a Class Entity
*/
CLASS,
/**
* Represents an Object Entity.
*/
OBJECT,
/**
* Represents a Property Entity
*/
PROPERTY,
in the EntityType. Although I would prefer an extensible framework that
would allow to extend the possible entity types without changing an enum
in the platform (for any API user to be able to define its own
references), I think this is fairly extensible (these are key concepts
in the xwiki model and I don't think they would be changed that soon,
and their interpretation is flexible, they could be combined with any
parent to generate either references to class definitions or instances).
here's my +1 for this.
+1 in general but this raises the question of choosing how we name these entities in the
new model. For example in sandbox I have the following right now:
- Object
- ObjectDefinition
- ObjectDefinitionProperty
2/ I would also need a 'standard' string
serialization for these. Now,
there's also the option to do it in my own module (annotations) because
only I need it ftm, but I prefer to have a platform wide approach. Opinions?
There are 2 choices, with a potentially different combination of separators:
a/ wiki:Space.Page^className[objectNumber]#property
pros: it's a suggestive way to access objects by number ([] is the
standard syntax for array indexed access and the objects are accessed by
index), [] is supported by JCR so maybe we should support it too
cons: [] is somewhat inconsistent with all other separators which are
just one separator, to the left (right) of the entity, harder to
implement the [] separators on the current framework
b/ wiki:Space.Page^className#objectNumber$property
pros: inline with the separator usage we already have (and easier to
implement for this reason), could be easier refactored to contain an
object name instead of the number
cons: $ separator can collide with velocity syntax (can potentially
cause trouble when used in velocity -- an alternative could be the pipe
|), could be harder to drop the object number part of the reference to
refer a property in a class (if wanted, in the future)
I have no other argument between a) and b) but the implementation speed
one, so I'd go for a b)-like approach, in the spirit of the current
separators.
Well from a technical pov both a/ and b/ require supporting multivalues. This means
changing several classes. For exemple we'd need to have both EntityReference and some
kind of IndexedEntityReference that would add get/setPosition() methods.
We'd need to rethink quite a few things probably since otherwise we'd need to use
a cast to get access to it, which isn't good.
Alternatively we'd need to add get/setPosition() in EntityReference but they
wouldn't have much meaning (we'd consider they always return 0 for ex) for
non-multivalued references.
Now in term of serialization I find the [] option (ie option a) more natural for a user
and more readable. It's slightly more complex to implement but that shouldn't be
our deciding factor IMO.
Re the separator chars, they look ok to me.
Thanks
-Vincent