[GROOVY-2046] MethodClosure iterators could loop forever

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Won't Fix
• Affects Version/s: 1.1-beta-2
• Component/s: groovy-jdk
• Flags: Patch
• Assignee: Unassigned
• Reporter: Ken Bloom
• Created: 12/Aug/07 17:25
• Updated: 05/Apr/15 14:44
• Resolved: 01/Apr/13 07:22

Description

//generates an infinite sequence of Fibonacci numbers
def fibonacci(Closure yield){
    def a=0
    def b=1
    def temp
    while(true){
        yield(b)
        temp=a
        a=b
        b=a+temp
    }
}

//BROKEN: the groovy runtime wants to run Fibonacci to termination, loading values into an array.
//this generates an out of memory error, before ever calling the closure once.
 this.&fibonacci.find{it % 20 == 0}

The proper solution is to use the attached Generator class that can properly invert control using threads, and only generates values on demand. I've also posted this solution at http://docs.codehaus.org/display/GROOVY/Iterator+Tricks for now, but it might be better to put it into the GDK.

Issue Links

• is related to: GROOVY-54 Add generator syntax similar to Python's