The Python Apprentice

Summary

• Python object references

  • Think of Python working in terms of named references to objects rather than variables and values.

  • Assignment doesn't put a value in a box. It attaches a name tag to an object.

  • Assigning from one reference to another puts two name tags on the same object.

  • The Python garbage collector will reclaim unreachable objects - those objects with no name tag.

• Object identity and equivalence

  • The id() function returns a unique and constant identifier but should rarely, if ever, be used in production.

  • The is operator determines equality of identity. That is, whether two names refer to the same object.

  • We can test for equivalence using the double-equals operator.

• Function arguments and return values ...