What is a parameter in etoys?

On 28.03.2011, at 14:17, Christine Murakami wrote:

Do you have some documentation on how parameters work in Etoys and what they can accomplish? I looked it up in your Floss manual but it was unclear to me where to find that information.

Many tiles in Etoys have a parameter. It is a value that influences the behavior of that tile.

For example, the "forward by" tile has a parameter that specifies how far the object should move. The "make sound" parameter specifies which sound to make. Etc.

You can also make your own tiles. When you create a new script, a tile for it is placed in an object's "scripts" viewer category. That tile can be used in another script.

The "add parameter" menu entry lets you add a parameter to your own tile. If you use that new tile in another script, you can set a specific value for the parameter just like with any other tile. 

Inside the script for your tile, that parameter is shown in the title bar. It is called "number" (unless you change the parameter type). You drag this "number" tile and use it like any variable tile in that script.

E.g. in this script, I used the "number" tile four times:

Every time you use your new tile, you can give it another "concrete" value. That's why in the script itself, you only have the "abstract" value called "number". (Computer scientists call the concrete values "arguments" and the abstract values "parameters", but even programmers get confused about the distinction)

Note that after adding a parameter, you can not set your script to "ticking" anymore, because it now needs a parameter. It only gets a concrete value for the parameter from another script where your tile is used. Additionally, you can set a value in the viewer, and hit the yellow button to run your script with that value:

- Bert -

_______________________________________________
squeakland mailing list
[hidden email]
http://lists.squeakland.org/mailman/listinfo/squeakland

Ok, I'll do it tonight :)

On Mon, Mar 28, 2011 at 1:51 PM, Bert Freudenberg <[hidden email]> wrote:

On 28.03.2011, at 15:58, Ricardo Moran wrote:

Great explanation! I didn't know the difference between "arguments" and "parameters" :)

http://en.wikipedia.org/wiki/Parameter_(computer_programming)#Parameters_and_arguments

BTW, is this written somewhere? It would be cool to add it to the manual...

Go ahead and add it :)

- Bert -

On Mon, Mar 28, 2011 at 10:02 AM, Bert Freudenberg <[hidden email]> wrote:

On 28.03.2011, at 14:17, Christine Murakami wrote:

Do you have some documentation on how parameters work in Etoys and what they can accomplish? I looked it up in your Floss manual but it was unclear to me where to find that information.

Many tiles in Etoys have a parameter. It is a value that influences the behavior of that tile.

For example, the "forward by" tile has a parameter that specifies how far the object should move. The "make sound" parameter specifies which sound to make. Etc.

You can also make your own tiles. When you create a new script, a tile for it is placed in an object's "scripts" viewer category. That tile can be used in another script.

The "add parameter" menu entry lets you add a parameter to your own tile. If you use that new tile in another script, you can set a specific value for the parameter just like with any other tile. 

Inside the script for your tile, that parameter is shown in the title bar. It is called "number" (unless you change the parameter type). You drag this "number" tile and use it like any variable tile in that script.

E.g. in this script, I used the "number" tile four times:

<PastedGraphic-1.png>

Every time you use your new tile, you can give it another "concrete" value. That's why in the script itself, you only have the "abstract" value called "number". (Computer scientists call the concrete values "arguments" and the abstract values "parameters", but even programmers get confused about the distinction)

<PastedGraphic-3.png>

Note that after adding a parameter, you can not set your script to "ticking" anymore, because it now needs a parameter. It only gets a concrete value for the parameter from another script where your tile is used. Additionally, you can set a value in the viewer, and hit the yellow button to run your script with that value:

<PastedGraphic-6.png>

- Bert -

_______________________________________________
squeakland mailing list
[hidden email]
http://lists.squeakland.org/mailman/listinfo/squeakland

_______________________________________________
squeakland mailing list
[hidden email]
http://lists.squeakland.org/mailman/listinfo/squeakland