[squeakland] What are the differences between a Holder and a
scott.wallace at squeakland.org
Tue Dec 8 00:14:48 EST 2009
On Dec 7, 2009, at 6:57 PM, Steve Thomas wrote:
> Here are the functional differences I have found so far:
> • A holder automatically orders things for you visually
> • A holder will "resize" to fit its contents (once something is put in)
> What other differences are there?
> Venn Diagram please . . .
A "Holder" is simply a "Playfield" which has had some of its "playfield options" set a particular way that has been found suitable for a number of purposes, particularly for classic "holder-based animations".
The three playfield-option settings that distinguish what we commonly call a Holder are:
"auto-line-layout" is set to true (so that elements don't overlap)
"indicate cursor" is set to true (so that the "selected" element is shown with a black border)
"resize to fit" is set to true
So any "playfield" can be made to behave entirely, or partially, like a "holder", simply by adjusting its playfield options; the Holder in the Supplies flap is offered only as a convenience -- it's simply a plain Playfield with the three options set.
(For example, try this: Get a "Playfield" from Supplies. From its halo menu get the "playfield options" submenu, and "pin" it up. Now click the "behave like a holder" checkbox, and notice which three other options get changed.)
> They both have collection and playfield, um what's the right term(s)?
> • Categories?
> • Behaviors and Attributes?
> • Predicates and Objects?
> • Nouns and Verbs?
> • Heeelllllppppp? (no definitely no, help, that's why we are writing the manual ;)
AFAIK "viewer category" is the term in common use.
Holders and Playfields have identical viewer categories, with identical items in them, because (to repeat...) a Holder *is* nothing more than a Playfield with a few options set a particular way.
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