[OLPC-Philippines] CACM article: Scratch: Programming for All

[Cherry Withers]

Hi Ray and all,

Here are some things that I found on Squeakland regarding Scratch and Etoys
comparison. There are pros and cons to both:

What is special about Etoys? Put your ideas here or send an email to
squeakland at squeakland.org.

   - The integration of "etoyish apps"
      - Graphs: With Ned Konz' "NetMorphs" you could produce things like
      petrinets <http://scg.unibe.ch/download/petitpetri/>
      - Kedama
      - Dr. Geo (to be coming)
   - Real subroutines (as opposed to Scratch)
   - Unframed interactive environment for wider and deeper experience. Well,
   one may say it is a disadvantage because of the white page syndrome it
   induces...


   - Clean open source license now (opposed to the source restrictions in
   scratch)

from Bert Fruedenberg's mail (answer to Bill Kerr)

The power of Scratch lies in its limited scope - several years of
development and refinement went into it to find the smallest set of features
that make it easily teachable while still broadly applicable.

There are others who could describe the Squeak/Etoys philosophy better than
me, but one of its core ideas is "no limits".

Where Scratch is a closed environment, Etoys provides just a thin layer of
visual scripting on top of a much larger system. There are literally
hundreds of objects that can be used as building blocks, from basic ones
like rectangles, ellipses, polygons, or text, to complex ones like a book or
a MIDI sequencer or video player or a working chess game (in Scratch there
are only bitmap-sprites). In Etoys you can change coordinate systems, or
embed objects into each other creating hierarchical animations, or connect
objects with arrows to create diagrams that are fully scriptable, etc. In
Scratch, every Sprite is separate, and they can communicate with others only
by broadcasting - this is more limited but much easier to learn, and less
prone to errors.

And if all that is not enough (there are always things the designers can't
anticipate) Etoys lets you escape to the full Squeak environment. While
Scratch is implemented in Squeak too, you cannot access it. Again that
limitation was a conscious trade-off (for example it enables "players" for
Scratch projects to be implemented in other languages).

Here are a few examples of my own projects in the Squeak showcase that I
think would be hard to recreate in Scratch.

Collision Physics
http://squeakland.org/showcase/project.jsp?id=7052
(objects with collision sensors adding their forces to influence motion,
this one is pure Etoys)

OLPC-XO-Display
http://squeakland.org/showcase/project.jsp?id=7050
(adds a new Squeak class to simulate the pixel pattern of the XO's display)

Euros
http://squeakland.org/showcase/project.jsp?id=7055
(connects to a web service to get currency conversion rate using a few lines
of Squeak scripting)

One of the fundamental Etoys ideas is that "authoring is always on", hence
there are no designated screen areas reserved for authoring tools. In fact,
the tools cannot be used just on the user-created content, but on the tools
themselves. This is a powerful idea in our opinion, it helps in demystifying
the tools.

You can have both tile scripts and textual scripts in Etoys, too. The
difference is that there is no real need to use the textual scripting for
the same stuff you can do with tiles. It's to access the advanced features,
but you will have to know Squeak first to even know what to look for.

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Cheers,

Cherry


On Wed, Nov 25, 2009 at 10:59 PM, <rayb at apc.edu.ph> wrote:

> Hi, all,
>
> The cover story of the November issue of Communications of the ACM is about
> the Scratch visual programming environment:
> http://cacm.acm.org/magazines/2009/11/48421-scratch-programming-for-all/fulltext
>
> Scratch is one of the activities installed on the XO.  A related package is
> Etoys --mentioned in the article but not discussed further.  About all I
> know of these packages is that both are implemented in Squeak Smalltalk and
> both enable multimedia authoring.  So I ask those in the know: which would
> be better for introducing programming to middle school or high school kids?
>
> Best,
>
> Ray
> _______________________________________________
> OLPC-Philippines mailing list
> OLPC-Philippines at lists.laptop.org
> http://lists.laptop.org/listinfo/olpc-philippines
>
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