License: The Etoys Manual will be dual-licensed under GPL (standard for FLOSS Manuals) and MIT (standard for Etoys). By contributing, you agree that your edits can be used under both the GPL and MIT licenses.
About Siblings (by Karl)
If you hold down shift while copying with the green halo handle you make a copy.
Almost... What you now have are two sibling players, each of which is a "Player" or "Object" in its own right. (Also copies made by the Player Copy tile are siblings.) Each players wears its own separate Morph as its costume. The siblings are related in that they share certain things in common, in particular: scripts and variable definitions. So if you add a variable to one sibling, all siblings will have their own instance of that variable with the same name. The same name, but the values can be different. For example if I add a variable called "speed" to one sibling, all siblings will have a variable with that name. But I can have one sibling with speed=5 and another with speed=10. Same variable name different values.
Also if I add a script to one sibling, all siblings will have the same script (and same scripting tiles, if I change it in any sibling at anytime). But although siblings share a script, each sibling has its own private "status" for that script, i.e.remembers separately whether the script as used by this instance is "normal", "paused,", or "ticking", or set to trigger on mouse-up, etc.; and what the tick-rate is.
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
So why would you use siblings? Well besides teaching one of the most fundamental concepts of object oriented programming, you could use siblings in a game to make characters that have similar behaviors (aka scripts) but different looks (you can change the looks by either re-drawing the sketch or by setting the Sketch's graphic (if the object is a Sketch or image you copied in) or changing its size and colors. You could also have ships in a game that keep track of how many times they were hit (using a variable to count the # of hits). That way you can program a basic ship once and make multiple siblings. Then if you decide to change the behavior (ex: modify a script, or add a new variable), you can change it once and all the siblings are changed.
Siblings could also be used to try to simulate or model real world behavior. For example deer population or some other animal. You could create an Object that simulates the behavior of a deer: searches for food, ages, breeds (at a certain age), etc. and make sibling copies of that one object. Then each Sibling (aka individual instance of the Class Deer which you have defined) could age, search for food (and find it or not which could affect its life expectancy), etc at its own rate. You could also create predators and food that grows. Then run multiple simulations varying the amount of food, starting number of dear, # of predators, etc.
#NOTE: Need to point to some good examples in Etoys and lesson plans from Internet
If the "all instances" box is not checked in AllPlayers, you'll see the scripts for only one player of each sibling group. This will give you "control" over the scripts of only one of the players. If you want to be able to "control" scripts for both of the siblings, make sure the "all
instances" checkbox is checked.
#DEVELOPER NOTE: We refer to "siblings" but don't have a formal term for the "class". We don't much use the terms "class" and "instance" in the etoys UI, nor in any documentation I'm aware of. (A notorious exception is the "all instances" checkbox in the all-scripts tool.)
Hmm... maybe the checkbox should read "all siblings" rather than "all instances"...
#DEVELOPER REQUEST: AFAIK, it's fine to have an all-scripts tool open as you create, delete, rename, and otherwise manipulate objects and scripts; I'm not aware of situations where it "misses" anything, but if you can describe a sequence of steps leading to such a situation, it would be helpful.
There has been error in communication with Booktype server. Not sure right now where is the problem.
You should refresh this page.