How does variable binding actually work in groovysh?

Question

Here's the crux of what I don't understand:

% groovysh
Groovy Shell (1.8.6, JVM: 1.6.0_21)
Type 'help' or '\h' for help.
------------------------------------------------------
groovy:000> class vars {
groovy:001> static int x = 1;
groovy:002> }
===> true
groovy:000> println new vars().x
1
===> null
groovy:000> println vars.x
ERROR groovy.lang.MissingPropertyException:
No such property: vars for class: groovysh_evaluate
Possible solutions: class
        at groovysh_evaluate.run (groovysh_evaluate:2)
        ...

If vars resolves to something in the expression new vars().x, why not also in the expression vars.x? It's like a phantom identifier that only actually exists for purposes of instantiation.

Answer 1

Your code doesn't work because you are using the wrong naming conventions. You should write the class with a capital V. This way the Groovy shell knows you are referring to a class, instead of a variable, in case the Groovy cannot determine it.

This is what you really want:

groovy:000> class Vars {
groovy:001>     static int x = 1
groovy:002> }
===> true
groovy:000> Vars.x
===> 1

Hope that helps!

Answer 2

Your problem is that vars is a class, not an object, and x is not declared as a static property. The best practice is to always name your classes with an upper case letter to prevent this kind of confusion.