1. A method for executing a machine code based on a dynamic language, the method comprising: creating a guard as a value stored in a data structure and representative of an expected condition for a reusable portion of the machine code, creating the guard includes allocating an object to be the guard in memory, a predetermined slot of the object is used as the guard; comparing the value representative of the expected condition to an actual value encountered later during execution of a portion of the machine code, remaining object contents are irrelevant in the comparing of the value representative of the expected condition to an actual value encountered later during execution of a portion of the machine code; executing the machine code if the actual value corresponds with the value representative of the expected condition; and invalidating the guard if the expected condition changes.