Greeter.py

import ast

class Greeter:
        def __init__(self):

                #m = "Hello world!"

                assignment = ast.Module(body=[ ast.Assign(targets = [
                        ast.Name(id = 'm', ctx = ast.Store())],
                        value = ast.Str(s="Hello world!"))
                        ])
                ast.fix_missing_locations(assignment)

                co = compile(assignment, "<ast>", "exec")
                exec(co)

                self.message = m