Practical Maximum number of fields on a card

[Richard Gaskin]

Richard MacLemale wrote:

> I'm making a gradebook.
> 
> Figure it this way - with a maximum of 50 students in a class, and a maximum
> number of 50 assignments per quarter, that's 2,500 possible individual
> grades.  My idea is to have those fields grouped and then add scrollbars to
> scroll the group.  I've done a prototype and this approach works fine - even
> with a grade entered in all 2,500 fields, and with 2,500 fields on each of
> 50 cards!  Scroll speed is good and it seems stable.  This is under OS X.
> Essentially what I'm doing is an imitation spreadsheet with each cell being
> a field.
> 
> I agree that this is an extreme number of fields for a card, which is why I
> wanted to see if there were some magical number of fields per card that
> should not be exceeded.
> 
> I looked at other approaches to this and I haven't thought of anything
> better.  You can simulate a spreadsheet with a locked field with the lines
> showing, but I wanted users to be able to easily and instantly click on any
> "cell" and edit the info there.  That feature is mandatory.
> 
> Another approach would be to only show 5 or 10 columns of the "spreadsheet",
> and have the user view the assignments that way, using the "page" metaphor
> (this page has 10 columns, turn the page, the next page has 10 columns,
> etc.)  The data could then be stored on separate cards, or in a separate
> stack, or in a text file, or even right there in the fields, but then the
> user has to "page" through their gradebook.  I really wanted to stick to the
> idea of being able to see and scroll through a whole quarter in one
> scrollable field.  Other gradebooks can do it and it is expected.
> 
> Like I said, the prototype is working fine under OS X.  I have launched it
> under Classic, and it runs fine there, too, but I can't tell how much RAM
> it's using until I try it out on an actual OS 9 Mac.
> 
> If MetaCard had a spreadsheet object, I'd just use that.  But using a field
> to pretend it's a spreadsheet is not the same because you can't interact
> with it in the exact same way.  This prototype is working fine, but I wanted
> to know if there were theoretical maximums I was ignoring...

Traditional spreadsheets use one list field for display, and create an
editable text field on the fly when the user clicks a cell.   Suck an
approch reduces your object count to 2 -- just hide the editable field on
closeField, and when you need it again calculate its rect and show it over
the cell the user clicked on.

Then again, if your current layout is working well, there may be no need to
change it. 

-- 
 Richard Gaskin 
 Fourth World Media Corporation
 Custom Software and Web Development for All Major Platforms
 Developer of WebMerge 2.0: Publish any Database on Any Site
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