groovy

MethodClosure iterators could loop forever

Details

  • Type: Bug Bug
  • Status: Closed Closed
  • Priority: Minor Minor
  • Resolution: Won't Fix
  • Affects Version/s: 1.1-beta-2
  • Fix Version/s: None
  • Component/s: groovy-jdk
  • Labels:
    None
  • Patch Submitted:
    Yes
  • Number of attachments :
    1

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

Wish - General wishlist item GROOVY-54 Add generator syntax similar to Python's

  • Major - Major loss of function.
  • Closed - The issue is considered finished, the resolution is correct. Issues which are not closed can be reopened.

Activity

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Ken Bloom added a comment -

Updated version of Generator.java, always garbage collects correctly every time.

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Ken Bloom added a comment - Updated version of Generator.java, always garbage collects correctly every time.
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Guillaume Laforge added a comment -

I haven't really looked into either the problem or the solution, but as a first remark, Groovy is coded in JDK 1.4 only, so no patches with generics will be applied to groovy-core.

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Guillaume Laforge added a comment - I haven't really looked into either the problem or the solution, but as a first remark, Groovy is coded in JDK 1.4 only, so no patches with generics will be applied to groovy-core.
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Ken Bloom added a comment -

Here's a Java 1.4 compatible version of Generator.java

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Ken Bloom added a comment - Here's a Java 1.4 compatible version of Generator.java
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Andres Almiray added a comment -

If I remember correctly generators will be added post 1.6, won't they?

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Andres Almiray added a comment - If I remember correctly generators will be added post 1.6, won't they?
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Pascal Schumacher added a comment -

I guess it was decided not to add generators to the gdk for now. There is also Groovy Stream now. Therefore I'm closing this issue.

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Pascal Schumacher added a comment - I guess it was decided not to add generators to the gdk for now. There is also Groovy Stream now. Therefore I'm closing this issue.

People

  • Assignee:
    Unassigned
    Reporter:
    Ken Bloom
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Dates

  • Created:
    Updated:
    Resolved: