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Re: Creating pointer in structure [message #27729 is a reply to message #27713]

Thu, 01 November 2001 14:49

John-David T. Smith is currently offline

John-David T. Smith
Messages: 384
Registered: January 2000

Senior Member

"Pavel A. Romashkin" wrote:
>
> JD Smith wrote:
>>
>> One other case where having true null pointers is useful: when saving
>> objects or structures, it's sometimes useful to kull out useless bits
>> (like widget states and id's), which aren't really appropriate for
>> keeping on disk.
>
> Let's see... A widget ID costs us 4 bytes. To fill up one kilobyte on
> your 80 Gb disk, it'll take... wait... 250 widgets. I have never been
> able to make even that many. My screen isn't big enough. If I stored a
> droplist widget with its value array, 100 characters wide by 1000
> entries long (which is crazy by itself), that would take up 100 Kb,
> roughly, right?
>
> The time needed to weed out GUI elements before saving seems to be worth
> more than the space savings. I just re-fill my restored, useless GUI IDs
> with new IDs when I restore older legacy structures, and for the newer
> code, I drop GUI altogether for saving, creting it from scratch on
> restore by the Restore method.
>
> I can appreciate it though if the reason not to store widget hierarchies
> is not so much storage space driven as it contradicts JD's aestetic code
> of IDL programming :-)
>

A more useful reason (for non-aesthetes) to avoid saving unnecessary
data: it may contain implicit definitions of structures or object
classes which you don't want to maintain as an external type, but keep
malleable and flexible. See the copious postings on the pitfalls of
restoring saved objects for more info on this subtle but important
problem.

JD

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[Message index]

		Re: Creating pointer in structure By: hcp on Fri, 02 November 2001 08:31
		Re: Creating pointer in structure By: Ron Syml on Fri, 02 November 2001 08:02
		Re: Creating pointer in structure By: K. Bowman on Fri, 02 November 2001 07:21
		Re: Creating pointer in structure By: John-David T. Smith on Thu, 01 November 2001 14:49
		Re: Creating pointer in structure By: Pavel A. Romashkin on Thu, 01 November 2001 14:19
		Re: Creating pointer in structure By: John-David T. Smith on Thu, 01 November 2001 12:57
		Re: Creating pointer in structure By: Pavel A. Romashkin on Thu, 01 November 2001 08:56
		Re: Creating pointer in structure By: Paul van Delst on Thu, 01 November 2001 07:07
		Re: Creating pointer in structure By: David Fanning on Thu, 01 November 2001 07:01

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