[Dev] Action items from collections code/design review

[Ted Leung]

On Sep 19, 2005, at 2:08 PM, Phillip J. Eby wrote:

> At 01:31 PM 9/19/2005 -0700, Alec Flett wrote:
>
>> Ted Leung wrote:
>>
>>> One of the items is to move away from use of onValueChanged and  
>>> go  back to using constructors for creating various collection  
>>> kinds.   Unfortunately, this
>>> means that we wouldn't be able to use update to change existing   
>>> instances in the repository.
>>>
>>
>> As I recall, the issue around this was that if we marked an  
>> attribute as "readonly" then there wasn't an obvious way to  
>> actually initialize that attribute. If Andi can give us a way to  
>> initialize the attribute, and tell Phillip about it so he can make  
>> the schema stuff initialize correctly, then can't we make  
>> 'sources' be readonly?
>>
>> Also, I just today noticed InclusionExclusionCollection's 'setup'  
>> method. I'm curious why some of this stuff can't be just set in  
>> the constructor? I think this is kind of tied up in this  
>> onValueChanged/readonly sources issue, which is why I bring it up.  
>> I'm hoping maybe pje will have some brilliant idea how to get rid  
>> of 'setup' because it kind of breaks our model of just using  
>> 'update' to initialize and create items.
>>
>
> I've been kind of thinking that allowing attributes' defaultValue  
> and initialValue to be functions instead of values would solve this  
> and eliminate other kinds of constructor fiddling that currently  
> exist.  Beyond that, this specific problem really needs a sort of  
> "derived attribute", which would be a useful feature to have in  
> general.
>
> Anyway, I don't have any ideas that are more than half-baked on  
> this at the moment, so I'm inclined to say we should stick with  
> what already works for the time being.  The TDD folks like to say  
> they want "clean code that works", but they also point out that you  
> have to start with the code that works, and *then* you clean it.   
> It doesn't work so well the other way around.  :)

+1