Script objects

From GNUstepWiki

Script object looks like ordinary object. However, it's behaviour is described by small scripts - methods written in some scripting language.

They can be used for:

  • Custom application objects
  • Event and notiication handlers
  • Objects in servers with customisable behaviour
  • ...

NOTE: See TODO list at the end of this page.


Contents

Using script objects

Just send it a message as to any other object:

[object sayHi];

Creating script objetcs

object = [STScriptObject scriptObject];
[object setEnvironment:someScriptingEnvironment];

Adding methods

Create a source:

source = @"sayHi Transcript showLine: 'Hi.'. ^self".

or

source = [NSString stringWithContentsOfFile:@"SomeFile"];

Get the the proper engine for a language used in the source:

engine = [STEngine engineForLanguageWithName:@"Smalltalk"];

create a method:

method = [engine methodFromSource:source
                      forReceiver:object
                    inEnvironment:Environment];

and finally add the method to the object:

   [object addMethod:method];

Methods with arguments

Well, no difference to any other methods. If you have source:

source = @"sayHiTo:someone Transcript showLine: ('Hi ', someone). ^self";

you can do:

[object sayHiTo:@"World"];

Script object interface

Script object understands following:

  • addMethod:aMethod
  • removeMethod:aMethod
  • removeMethodWithName:aString
  • methodWithName:aString
  • methodNames
  • respondsToSelector:aSelector

TODO

Here are unimplemented features of the Script Objects. Feel free to add them, if you have a bit of time. Please consult with the author of StepTalk and on the gnustep lists.

  • object variables (this is high priority)
  • inheritance of variables and methods (traits like in Self?)
  • object archiving
  • object cloning (copying)
  • script object builder application (it should be something simple)

See also: StepTalk, Scripting