Script binding does not work before calling Script.run() - variables

Question

I've the following test code to figure out how variable binding works. So this is what I want to import/include;
# importee.groovy
import groovy.transform.Field
#Field top = 60
number = 44 // binding variable
int ratio = 4.5
return this
which I call it from;
# importer.groovy (version1)
import groovy.lang.GroovyClassLoader
def gcl = new GroovyClassLoader()
def clazz = gcl.parseClass(new File("importee.groovy")) )
assert clazz.name == 'importee'
def script = clazz.newInstance()
//script.run()
println("binding variable:
${script.getBinding().getVariable("number")}")
So, if I don't run the script, my test code throws "MissingPropertyException" on the last print statement. This is not happenning if I call def script = evaluate(new File("importee.groovy")) instead of using GroovyClassLoader like this;
# importer.groovy (version2)
def script = evaluate(new File("importee.groovy"))
println("binding/global variable: ${script.number}")
Since both methods return a Script instance, I got a little bit confused on why I have to call the run() method in the first case. Can someone explain where I fail to understand please?
Thanks

Answer 1

run groovyconsole (distributed with groovy)
type a simple script:
number=44
return this
select menu Script -> Inspect Ast
and in the new window Groovy AST Browser select phase = Conversion
you will see your groovy script but converted to a Script class like this:
public class script1548245785832 extends groovy.lang.Script {
public script1548245785832() {
}
public java.lang.Object run() {
number = 44
return this
}
}
this is the actual code generated for your script.
as you can see the constructor is empty, so no information about number property after you call newInstance()
but after you call run() you actually run your script.
your script could be a class like this:
class Importee {
int number=44
public Object run(){
println number
}
}
in this case it will be enough to create instance of class without calling run() method and get the value of number variable...
def clazz = gcl.parseClass( new File("Importee.groovy")) )
def script = clazz.newInstance()
println("the variable: ${script.number}")