86 lines
2.2 KiB
Markdown
86 lines
2.2 KiB
Markdown
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\[ [Index](index.md) | [Exercise 1.5](ex1_5.md) | [Exercise 2.1](ex2_1.md) \]
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# Exercise 1.6
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*Objectives:*
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- Defining modules
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- Using the import statement
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*Files Created:* None
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**Note:**
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For this exercise involving modules, it is
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critically important to make sure you are running Python in a proper
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environment. You may need to check the value of `sys.path` if you
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can't get import statements to work. Ask for assistance if everything
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seems broken.
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Before starting this exercise, first restart your Python interpreter session. If using IDLE, click on
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the shell window and look for a menu option "Shell > Restart Shell". You should get a message like this:
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```python
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>>> ##################== RESTART ##################==
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>>>
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```
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If you are using Unix, simply exit Python and restart the interpreter.
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## (a) Using the import statement
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In previous exercises, you wrote two programs `pcost.py` and
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`stock.py`. Use the `import` statement to load these
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programs and use their functionality:
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```python
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>>> import pcost
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44671.15
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>>> pcost.portfolio_cost('Data/portfolio2.dat')
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19908.75
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>>> from stock import Stock
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>>> s = Stock('GOOG', 100, 490.10)
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>>> s.name
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'GOOG'
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>>> s.cost()
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49010.0
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>>>
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```
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If you can't get the above statements to work, you might have placed
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your programs in a funny directory. Make sure you are running Python
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in the same directory as your files or that the directory is included
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on `sys.path`.
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## (b) Main Module
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In your `pcost.py` program, the last statement called a
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function and printed out the result. Modify the program so that this
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step only occurs if the program is run as the main program. Now,
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try running the program two ways:
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First, run the program as main:
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```
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bash % python3 pcost.py
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44671.25
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bash %
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```
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Next, run the program as a library import. You should not see any
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output.
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```python
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>>> import pcost
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>>>
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```
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\[ [Solution](soln1_6.md) | [Index](index.md) | [Exercise 1.5](ex1_5.md) | [Exercise 2.1](ex2_1.md) \]
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----
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`>>>` Advanced Python Mastery
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`...` A course by [dabeaz](https://www.dabeaz.com)
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`...` Copyright 2007-2023
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. This work is licensed under a [Creative Commons Attribution-ShareAlike 4.0 International License](http://creativecommons.org/licenses/by-sa/4.0/)
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