What is the priority of "error-event" and "catch"?
How can I implement an analog for such pseudocode?:
Working so that if body rises error or user throws something, "finish-sequence" is evaluated either, but upper function calling this block will still think that user throw or system error is raised in a "body".
Imitating this with (if (not (catch ...)) ... (throw ...)) will affect error-code, I think. And I also want to distinguish between errors and regular throws...
Really, I can live successful without that now. Just a question about programming... :-)
Use the second syntax of catch described in the manual and read also about program flow and error catching here:
http://newlisp.org/DesignPatterns.html#program_flow
and here :
http://newlisp.org/DesignPatterns.html#error_handling
Note, that error-event had some limitations in versions previous to 8.6.7 when using in commandline invoked scripts.
You can nest multiple 'catch'. 'error-event' works only the top level when specifying the error version of 'catch' after 'error-event' then 'cath' will take priority.
Lutz
Oh! Thanks! I forgot about "Design Patterns" :-)
Now it's more clear.
With the second syntax of 'catch' you can easilyt write a (try body else) yourself:
(define-macro (try body else)
(if (not (catch (eval body) 'result))
(eval alternative)
result)
)
; now try this
(try (+ 3 4) (error-text)) => 7
(try (xyz) (error-text))
=> "invalid function in function eval : (xyz)"
In the body expression you could use 'throw-error' for exceptions you define your self, and 'else' could contain a more elaborate function to treat an error condition.
Lutz