access global variable in static scope - groovy

Question

Is there a way to access global variable, declared in the script, from the static method of the class, declared in the same script?
For example
def s = "12345"
class MyClass {
static def method() {
println s
}
}
Because that way it fails with the error
You attempted to reference a variable in the binding or an instance variable from a static context
which is expected though.

Answer 1

There is a related discussion at this question:
Groovy scope - how to access script variable in a method
Related in that both questions refer to using a global variable within a class, but this question differs somewhat in that you are seeking to use a static method which alters how you pass the script instance or binding (2 choices).
Passing the Script's Instance
import groovy.transform.Field
#Field def s = "12345"
class MyClass {
static def method(si) {
return si.s
}
}
assert MyClass.method(this) == "12345"
Passing the Script's binding
s = "12345" // NOTE: no 'def'
class MyClass {
static def method(b) {
return b.s
}
}
assert MyClass.method(binding) == "12345"

Answer 2

Well, the problem is that in Groovy there is no such thing as a global variable. What is loosely considered a global variable is actually a static property within some class.
For example, if you remove the println line so that the code compiles, you get something like this out of the compiler:
public class script1455567284805 extends groovy.lang.Script {
...
public java.lang.Object run() {
return java.lang.Object s = '12345'
}
...
}
public class MyClass implements groovy.lang.GroovyObject extends java.lang.Object {
...
public static java.lang.Object method() {
// This is where the println would have been.
return null
}
...
}
As you can see, an additional class is created and the the s variable is declared within the method run() of that class. This makes the variable inaccessible to your other class.
Note: Removing the def will not address this issue.
Solution
Your best bet is to place your "global variables" into a class, possibly as static properties, like this:
class Global {
static Object S = "12345"
}
class MyClass {
static def method() {
println Global.S
}
}

Answer 3

You included a variable type with the s variable (by using the def type). In a Groovy script, this is treated as a local variable - and local to the run() method that is generated - which is kind of like a main() class. As a result, the variable is not available in other methods or classes.
If you remove the def you will be able to make use of the s variable.
Here is the Groovy documentation that explains this further.