Class 30 — April 3

Moving on

Working Together – On a cautionary tale – New understandings

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Look both ways

• Back or ahead

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Zoom

• Link

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Nuance downloads (PDF, slide show)

• Program cautionary.py

• Module tale.py

• Program wipe.py

• Module zero.py

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Homework downloads

• Module aid.py

• Tester abet.py

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Agenda

• Consider module development

• Problem solve

• Consider parameter passing nuances

• Show if ( __name__ == '__main__' ) statement for aiding testing

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To do

• Examine parameter passing nuances

• Complete homework 26

• Complete homework 27

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Test 2

• Will be April 20. The final will be optional. The grading percentages will be updated to

• Homework: 20%

• Test 1: 35%

• Test 2: 35%

• Test 3: 10%

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Module self-testing downloads

• Module im_a_module.py

• Tester im_a_tester_program.py

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Tester statement if ( __name__ == '__main__' )

• Along with some built-in functions, Python provides each Python file with a built-in variable __name__.

• For a Python file being imported by another Python file, the variable is set to the name of imported file.

• For a Python file being run as a program, the variable is set to '__main__'

• With this if statement, a module can provide self-testing if run as a program.

• Why do you care about this functionality?

• Such testing will also be part of the modules for ongoing homework and fture tests

• Homework aid.py uses the if ( __name__ == '__main__' ) statement to support testing using abet.py.

if ( __name__ == '__main__' ): # __name__ is a built in python variable.

  import abet # it is set to __main__ if you are running

  # that module as a program

  # it is set to the name of the module

  # if it is being imported

  abet.test_rotate()

  abet.test_rotate_k_times()

  abet.test_common()

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Module of the day aid.py

• Examine and think about algorithms for the problems. However, do not write any code before class.

• Downloads

• Module aid.py

• Tester program abet.py

• Complete the implementation of three functions. None of your functions should get input or print output.

Function rotate( x )

• Updates list x by moving the last element of list x (if any) to the beginning of list x. This type of list transformation is often called a circular shift.

• In carrying out its action, the function modifies the contents of the list x in place (e.g., by list-modification methods like pop(), append(), and insert(), or by directly modifying individual elements of list x.

• The function returns None.

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Function rotate_k_times( x, k )

• Updates list x by performing k circular shifts.

• In carrying out its action, the function modifies the contents of the list x in place.

• The function returns None

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Function common( x, y )

• Returns a new list whose elements are those elements in x that are also in y. The ordering of elements in the return list should reflect their ordering in x.

• The function does not modify parameters x and y in any way.

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Slide show

 

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© 2020 Jim Cohoon

Resources from previous semesters are available.