How could I access the object from its property in an OOP

Hello,

I Have define two object. On handle object,and another object is beeng passed to the handle object as its properties. Assume like a handle object of Field, which includes some Robot-objects bounded to it as its property. Now, in a method inside the Robot Class I want to access some property of the field, like its dimension. Is there any way which does not includes definning a global variable?

Thank you,

Hadi Hajieghrary