On 31-Jan-08, at 3:17 PM, Eric Williams wrote:
>
> On Jan 31, 2008, at 1:39 PM, Lars Jensen wrote:
>
>>> True enough - but this seems like extra work to me. Why not just
>>> keep
>>> track of everything as you create it? That way you'll always know
>>> what's going on instead of having to repeatedly cycle through all
>>> the
>>> windows to find the one you want.
>>
>> "Keeping track of" is another way of saying "caching information
>> about". Caching is an optimization. Premature optimization is bad
>> because it increases complexity and therefore risk of bugs.
>> Therefore,
>> unless you have a need to keep track of something (e.g. for
>> performance reasons), it's generally better practice to ask the
>> system
>> for current information.
>>
>> Put another way: always ask the system, and if the system needs to
>> cache the info, it can. That way, the benefit of caching is spread
>> while the complexity remains contained.
>
> Yikes! So I shouldn't keep track of document windows when they are
> created? It's not as if a document window is going spontaneously
> materialize behind my application's back - document windows only come
> into existence when my app creates or opens a document. And when I go
> to shut down my application, I can cycle through each document object
> and tell it to close its window (instead of cycling through all the
> windows in memory, figuring out if they are document windows, and
> sending them a close command). This seems to me to be the very
> underpinnings of object orientation.
Just that the system already keeps a list of open Windows for you
Why duplicate that ?
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