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Re: What happens to 'def' attributes in scripts?

by Edward Sumerfield-2 :: Rate this Message:

Woo, I can answer this one.

When groovyc compiles this script it has to convert into java byte code. So, the n=1 become Test instance attributes, the def n=1 become main method local variables.

The case without def results in java looking something like this:

    class Test
    {
        Object n = 1
        Object m = 2

        public static void main(String args[])
        {
            add(m)
        }

        void add(Object another)
        {
            another += n
        }
    }

this works because there are no defs and the scoping of n and m remain accessible by the add method

However, add the def and they become local variables in the main method and now are not accessible by add.

    class Test
    {
        public static void main(String args[])
        {
          Object n = 1
          Object m = 2

            add(m)
        }

        void add(Object another)
        {
            another += n
        }
    }

On Tue, Jun 30, 2009 at 4:21 PM, Niels B Nielsen <niels.b.nielsen@...> wrote:

Hi,

When I have my users define their own script, they produce something similar to this:

Test.groovy

--------------

n=1

m=2

def add(another) {

int x = n+another

println "x is ${x}"

}

add(m)

-------------------------

The def method is added to Test.class, and the variables are added to the Binding. That much I have verified, but when the users sometimes write

def n=1

def m=2

The script fails to recognize n in the add method. (no such property: n for class: Test)

Clearly, neither n nor m is a field of class Test, nor are they present in the binding. However, m is still accessible to be an argument to the add method.

I can easily tell the user not to specify def in front of variables, only in front of methods, but I cannot fully explain why.

Where is the variable stored? In the main method? or just inline replaced during parsing? Hope you can help me with an answer.

Regards,

/Niels

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« Return to Thread: What happens to 'def' attributes in scripts?