[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