[Etoys] EllipseMorph and sibling instance

K. K. Subramaniam subbukk at gmail.com
Sun Apr 13 23:08:46 EDT 2008

On Monday 14 Apr 2008 2:47:12 am Scott Wallace wrote:
> When using siblings, what's really happening underneath is that there  
> is a custom Player "Class" is created to bear the shared code, and the  
> siblings are individual "Instances" of that class.  "Class" and  
> "Instance" are among the most fundamental concepts of object-oriented  
> programming, but we don't much use the terms "class" and "instance" in  
> the etoys UI, nor in any documentation I'm aware of.
The viewer category "an Object" contains a class tile. An EToy is initially 
in "UnscriptedPlayer" class. When the first script is created, the class gets 
reassigned to a unique Player<n> value. This value stays even if all the 
scripts in the Player are deleted. Should it revert to UnscriptedPlayer in 
this case?

> (A notorious   
> exception is the "all instances" checkbox in the all-scripts tool.)  
> We refer to "siblings" but don't have a formal term for the "class".  
> Hmm...  maybe the checkbox should read "all siblings" rather than "all  
> instances"...
and also in the "make a sibling instance ..." in the siblings menu item of red 
halo button.

The copy tile in miscellaneous category uses the term "clone" for sibling.

This mixing of metaphors (drama, family, genetics) is confuses children. So, I 
use the analogy of chorus dancers to explain this part of EToys. Each dancer 
in the group may wear a different costume, have different heights or 
locations on stage, but they all perform to the same script. One eight-year 
applied the concept to animate falling snow for a winter scene.


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