f-script-talk

[F-Script-talk] Problem with variables defined in block

[<kmo...@sp...>]

Hi,

I'm new to fscript, and stumbled upon something that really puzzles me. =20=

When I define a block directly from the prompt within the =20
fscript-application, and define a variable within that block, the =20
variable will be visible outside the block, too (after the block has =20
been sent 'value'). This is as I expected it. See this session for =20
example:

---------------------------------------------------------------------
 > blockFromPrompt :=3D [ otherString :=3D 'this works!'. ]

 > blockFromPrompt value

 > otherString
'this works!'
---------------------------------------------------------------------

However, when I load a block from a file, any variable defined in this =20=

block will NOT be visible outside. Compare this:

---------------------------------------------------------------------
 > codeFromFile :=3D NSString alloc initWithContentsOfFile: =20
'/Users/dunk/Desktop/testScript.fscript'

 > blockFromFile :=3D codeFromFile asBlock

 > blockFromFile
[
     someString :=3D 'test me!'.
]

 > blockFromFile value

 > someString

error: undefined identifier "someString"
---------------------------------------------------------------------

Why is the 'someString' variable not visible, just as the 'otherString' =20=

variable? Is this a bug or a feature? If it is a feature, I don't =20
really get it. Someone please enlighten me! =3D8-)

Apart from that, I think that fscript is very cool! I plan to use it in =20=

a game project of mine.

Cheers,
Knud

PS: I use version 1.2.4

------------------------------------------------------------------------=20=

-------
Knud M=F6ller - Institut f=FCr Sprachliche Informationsverarbeitung,
Universit=E4t zu K=F6ln
(Department of Linguistic Data Processing, University of Cologne, =20
Germany)
http://www.spinfo.uni-koeln.de/~kmoeller

[F-Script-talk] Re: Problem with variables defined in block

[Philippe M. <pm...@ac...>]

Dear Knud,

You get the expected behavior.

However, note that, actually, it is not the fact that you load the =20
source code of the block from a file that gets you this behavior but =20
the use of the "asBlock" method on a string. As stated in the manual: =20=

"... each block created by this method is in charge of its own =20
top-level workspace". In other words, the block created by this method =20=

has no knowledge of your F-Script session's workspace. Instead, it runs =20=

in its own workspace.

This may seems surprising at first. To better understand the rational =20=

of this behavior, ask yourself: how could the NSString asked to create =20=

a block (with the 'asBlock' method) know about your F-Script session? =20=

The answer is: it can't. Your NSString is an Objective-C object, like =20=

every object manipulated with F-Script. When it receives the 'asBlock' =20=

message, it doesn't know that this message comes from an F-Script =20
interpreter. Indeed, you can also directly send this message from an =20
Objective-C program as well.

What you need in order to achieve what you want is a way to ask the =20
current F-Script interpreter to create a block configured to use the =20
current workspace. By chance, the pre-defined identifier 'sys' refers =20=

to an object (of class System) which represent the current F-Script =20
interpreter, and provides the method you want (i.e., blockFromString:). =20=

Thus, if you write "sys blockFromString:codeFromFile", a new block will =20=

be created which will be configured to use the workspace of the =20
interpreter represented by the receiver (i.e., the current F-Script =20
interpreter).

Finally, I should add that you can directly save and load blocks =20
to/from files. See section 9 in the manual.

Hope this clarify things.

BTW, feel free to let us know about your game and how you use F-Script =20=

in this project.

Best,

Phil


Le lundi, 15 sep 2003, =E0 19:37 Europe/Paris, Knud M=F6ller a =E9crit :

> Hi,
>
> I'm new to fscript, and stumbled upon something that really puzzles =20=

> me. When I define a block directly from the prompt within the =20
> fscript-application, and define a variable within that block, the =20
> variable will be visible outside the block, too (after the block has =20=

> been sent 'value'). This is as I expected it. See this session for =20
> example:
>
> ---------------------------------------------------------------------
> > blockFromPrompt :=3D [ otherString :=3D 'this works!'. ]
>
> > blockFromPrompt value
>
> > otherString
> 'this works!'
> ---------------------------------------------------------------------
>
> However, when I load a block from a file, any variable defined in this =
=20
> block will NOT be visible outside. Compare this:
>
> ---------------------------------------------------------------------
> > codeFromFile :=3D NSString alloc initWithContentsOfFile: =20
> '/Users/dunk/Desktop/testScript.fscript'
>
> > blockFromFile :=3D codeFromFile asBlock
>
> > blockFromFile
> [
>     someString :=3D 'test me!'.
> ]
>
> > blockFromFile value
>
> > someString
>
> error: undefined identifier "someString"
> ---------------------------------------------------------------------
>
> Why is the 'someString' variable not visible, just as the =20
> 'otherString' variable? Is this a bug or a feature? If it is a =20
> feature, I don't really get it. Someone please enlighten me! =3D8-)
>
> Apart from that, I think that fscript is very cool! I plan to use it =20=

> in a game project of mine.
>
> Cheers,
> Knud
>
> PS: I use version 1.2.4
>
> =
-----------------------------------------------------------------------=20=

> --------
> Knud M=F6ller - Institut f=FCr Sprachliche Informationsverarbeitung,
> Universit=E4t zu K=F6ln
> (Department of Linguistic Data Processing, University of Cologne, =20
> Germany)
> http://www.spinfo.uni-koeln.de/~kmoeller

Re: [F-Script-talk] Re: Problem with variables defined in block

[<kmo...@sp...>]

Hi,

thanks for the quick and detailed answer. It really helped me to =20
understand what is going on behind the scenes a little bit better and =20=

solves my problem.
Am Montag, 15.09.03, um 23:20 Uhr (Europe/Berlin) schrieb Philippe =20
Mougin:

> Finally, I should add that you can directly save and load blocks =20
> to/from files. See section 9 in the manual.

Yes, I had seen that. but [Block save/load] will serialize/deserialize =20=

the Block-object, and not save a text representation, correct? And =20
since I want to be able to generate and manipulate my scripts in a text =20=

editor, I think a cannot use this method.

> BTW, feel free to let us know about your game and how you use F-Script =
=20
> in this project.

Well, it's nothing professional, but a project I want to submit to a =20
Macintosh game programming contest called uDevGames (see =20
http://www.idevgames.com/content/contest.php?id=3D10). The game ("Retro =20=

Maze") is an oldfashioned role playing game with a very simple, tile =20
based 3d-engine. The game's basic framework is done i Cocoa/ObjC. Now I =20=

plan to use fscript to glue everything together. More important, I want =20=

to attach scripts to various game objects (tiles, monster, walls, ...). =20=

These scripts will be executed whenever some condition is met (e.g. a =20=

tile's script is executed when the player walks over it) and provide =20
the game with the actual action.
I guess I could have used just about any scripting language to do that. =20=

However, fscript caught my eye through the articles on the =20
O'Reilly-network. It looked different, but very interesting and elegant =20=

- I was really fascinated by the fact that control structures are =20
implemented using blocks and messages! Since portability to other =20
platforms is not a concern for me, it doesn't matter that fscript is =20
only available on OSX at the moment.

Merci bien,

Knud
------------------------------------------------------------------------=20=

----------------
Knud M=F6ller -  Institut f=FCr Sprachliche Informationsverarbeitung,
Universit=E4t zu K=F6ln
(Department of Linguistic Data Processing,
University of Cologne, Germany)
http://www.spinfo.uni-koeln.de/~kmoeller

------------------------------------------------------------------------=20=

----------------

[F-Script-talk] Re: Problem with variables defined in block

[Philippe M. <pm...@ac...>]

Le mardi, 16 sep 2003, =E0 10:56 Europe/Paris, Knud M=F6ller a =E9crit :

>> Finally, I should add that you can directly save and load blocks=20
>> to/from files. See section 9 in the manual.
>
> Yes, I had seen that. but [Block save/load] will serialize/deserialize=20=

> the Block-object, and not save a text representation, correct?

Yes you're right.

I hope your game will do well!

Best,

Phil=