Mailing List Archive: 49091 messages
  • Home
  • Script library
  • AltME Archive
  • Mailing list
  • Articles Index
  • Site search
 

[REBOL] Re: Beginner's questions on REBOL/Core and REBOL/View

From: joel:neely:fedex at: 11-Sep-2002 9:09

Hi, Andreas, Welcome to REBOL and the list! ----- Original Message -----
> REBOL/Core > - error messages do not locate where the problem occurred > but present a very vage description of their orgin only > How can I retrieve the number of the faulty line? >
The short answer is "you can't". One feature of REBOL this differs from most other programming languages is that the distinction between "code" and "data" is not relevant. REBOL can evaluate anything, including blocks that were constructed as the result of evaluating other expressions. So, in general, the concept of "source line" simply isn't meaningful. For example: a: [b:] c: [2 + 2] d: append a c insert d first [print] do d (I'm composing at the keyboard on a borrowed machine, so forgive me if I make a typo...) Evaluating the above expressions constructs a new block and then evaluates that block. If an error had occurred during evaluating the last expression (the last value of D), how would we have any concept of "which line" was involved? Let me emphasize that I'm not criticizing the question, just trying to show how it depends on assumptions that may be true of other programming languages, but not of REBOL. Good luck with your learning, and please feel free to use this list any time you have questions. I've found it very open and helpful during my time with REBOL! -jn-