[ sisc-Bugs-807474 ] parameterize and call/cc can cause NullPointerException

Bugs item #807474, was opened at 2003-09-16 22:49
Message generated for change (Tracker Item Submitted) made by Item Submitter
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=379534&aid=807474&group_id=23735

Category: None
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: Chris Double (doublec)
Assigned to: Nobody/Anonymous (nobody)
Summary: parameterize and call/cc can cause NullPointerException

Initial Comment:
The following code demonstrates how to reproduce a

java.lang.NullPointerException when using a

continuation to call back into a parameterize block:



(define *a* #f)

(define *b* (make-parameter #f))



(define (test)

  (parameterize ((*b* 10))

		(begin

		  (call/cc

		   (lambda (k)

		     (set! *a* k)))

		  (display (*b*)) 

		  (newline))))



(test)

(*a* 20)



Gives:

java.lang.NullPointerException

	at

sisc.env.LexicalEnvironment.lookup(LexicalEnvironment.java:34)

	at

sisc.exprs.LexicalReferenceExp.getValue(LexicalReferenceExp.java:24)

	at sisc.exprs.AppExp.eval(AppExp.java:28)

...



After this the Sisc REPL exits.

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