Programming Assignment(PA) 1

• Take your time to read. I suggest printing out and taking notes.
• Readiness Quiz
• Testing and limit of 10 attempts to the autograder
• You need to test your code thoroughly before using autograder
  • you need to install pytest
  • you need to write a series of tests in test_dice.py

Modules

• script: .py file where Python program is saved. Intended to be run directly. Can have statements outside of a function.
• module: Python file for importing into a script or othe modules. It defines functions and can have variables that are intended to be used in other files that import the module
• Assume a file mymath.py
  • import mymath
  • __name__
    • "main" in mymath.py when not imported
    • "mymath" in mymapth.py when imported

• import a module, use filename without .py of module file
  • good practice: import statements at the top of the file
  • the code of the module is executed
    • if module imported >1, only executed one time
    • make us of __name__ to determine what is executed
  • use . to access contents of module

Import will execute the module

• what does that imply?
• if code outside of function in module, what happends when imported?
• if code inside of function in module, what happends when imported?
• function definitions are not executed
• statements outside of functions are executed the first time the import is performed
• unintended side effects of the import

Another way to import but different

from module_name import name1, name2 ...

• namespace is different
  • imported names are in the global namespace, that is, copies are made
• do not need the .

from math import pi
print(pi) # instead math.pi

Rename a module importing

import math as m
print(m.pi)

There is always more to learn ...

• next time

more on import and modules

• module contents are in a separte namespace
• namespace
  • internally a dictionary
  • key => object name
  • value => the object itself
  • four types of namespace
    • built-n; global; enclosing; local
• scope
  • namespace for global
  • namespace for each local
• dir()
  • list of defined names in a namespace
  • dir(object) objectt can be imported module

More about namespace

loading a module:
- a module object is created and inserted in sys.modules
- module object is a namespace that has definitions from the module
- adds module object to the global namespace
- dir() or dir(module_name)
- the code of the module is executed
- if module imported >1, only executed one
- a module object contains the definitions from the module

• packages: collection of related modules that provide some functionality. Will contain __init__ to indicate a package.
• library: bundle of code, can have 100s of modules
• Python standard library: comes with your installation of Python