From: Dave Thomas <dave@...>
Date: 2003-05-02T04:38:06+09:00
Subject: Re: [OO interface design] Pass-by reference VS encapsulation ?

Simon Vandemoortele wrote:

> Wouldn't I still need an object that keeps track of all the instantiated
> contacts. How else am I going to generate a sorted list of contact names
> for the UI ?
Surely all the Contacts that you search are the persisted ones: you 
don't want folks looking at possibly inconsistent reified ones.

 > Who is going to answer sophisticated search queries (give
 > me all contacts born between 1977 and 1987.) I could achieve this using
 > the ObjectsSpace in my client but is that really good design ?
 > Especially since many clients are probably going to want that query
 > functionality ...

Why not Contact itself? For example, in my web application, class User 
has class methods

   User.user_with_name(name)      -> aUser
   User.user_with_email(email)    -> aUser
   User.list_matching(criteria)   -> Array[user...]

where 'criteria' is an object representing search criteria, tied 
indirectly in to my persistence layer.

Anyway, a suggestion. Code your application. Code it many different 
ways. And see what you think of each. In some versions make a point of 
relaxing what you believe to be good design practices in favor of doing 
what seems natural. In others, design the snot out of it. And in the 
end, see which application feels 'right.'

And please let us know.


Cheers


Dave