[Zope3-dev] zwiki: performance of findChildren()

[Jeremy Hylton]

On Sat, 2003-04-26 at 14:36, Max M wrote:
> Why put the relation in the object? Isn't it better to have a container 
> with different relations?

It clutters up the API.  The fact that there is a relations object with
strange methods makes for more typing.  In the example, a many-to-many
relation is just a set and a Python set now has a standard API.  The 
descriptor also eliminates the need to indirect through a family of
accessor methods.

Under the covers, we can implement the relation however we like.  I
chose to hang the attributes directly on the object, but Shane would
probably want to put them in a separate table.

> # a relation object (a graph) exists "self.relations.developers_projects"
> 
> class SoftwareProject(object):
> 
>     def __init__(self, name):
>         self.name = name
> 
>     def __repr__(self):
>         return "%s(%r)" % (self.__class__.__name__, self.name)
> 
>     def developers(self):
>         return self.relations.developers_projects.get(self)
> 
>     def add_developer(self, developer):
>         return self.relations.developers_projects.relate(self, developer)

Note that you haven't assigned to self.relations anywhere.

Jeremy