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My delphi application runs scripts using JvInterpreter (from the Jedi project).

A feature I use is runtime evaluation of expressions.
Script Example:

[...]
ShowMessage(X_SomeName);
[...]

JvInterpreter doesn't know X_SomeName. When X_SomeName's value is required the scripter calls its OnGetValue-callback. This points to a function I handle. There I lookup X_SomeName's value and return it. Then JvInterpreter calls ShowMessage with the value I provided.

Now I consider switching to DelphiWebScript since it has a proper debug-interface and should also be faster than JvInterpreter.

Problem: I didn't find any obvious way to implement what JvInterpreter does with its OnGetValue/OnSetValue functions, though.

X_SomeName should be considered (and actually is, most of the time) a variable which is handled by the host application.

Any Ideas?

Thanks!

Folkert Hasenlust
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  • Have you considered making this variable a function that calls back to your application? Sure you lose the "Set" behavior but at least half of the job is done. – Nedko Feb 21 '13 at 16:29
  • I have - wouldn't work, though. The "SomeName"-Part of X_SomeName may be anything, so I can't declare it up front. That's why I need run-time evaluation. – Folkert Hasenlust Mar 06 '13 at 09:21

1 Answers1

1

You can do that through the language extension mechanism, which has a FindUnknownName method that allows to register symbols on the spot.

It is used in the asm lib module demo, and you can also check the new "AutoExternalValues" test case in ULanguageExtensionTests, which should be closer to what you're after.

Eric Grange
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