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Exercises/ex9_2.md

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+\[ [Index](index.md) | [Exercise 9.1](ex9_1.md) | [Exercise 9.3](ex9_3.md) \]
+
+# Exercise 9.2
+
+*Objectives:*
+
+- Learn how to create a Python package
+
+**Note**
+
+This exercise mostly just involves copying files on the file system.
+There shouldn't be a lot of coding.
+
+## (a) Making a Package
+
+In previous exercises, you created the following files that were related to
+type-checked structures, reading data, and making tables:
+
+- `structure.py`
+- `validate.py`
+- `reader.py`
+- `tableformat.py`
+
+Your task is to take all of these files and move them into a package called `structly`.
+To do that, follow these steps:
+
+- Make a directory called `structly`
+- Make an empty file `__init__.py` and put it in the `structly` directory
+- Move the files `structure.py`, `validate.py`, `reader.py`, and `tableformat.py` into the `structly` directory.
+- Fix any import statements between modules (specifically, the `structure` module depends on `validate`).
+
+Once you've done that, modify the `stock.py` program so that it looks exactly like this
+and that it works:
+
+```python
+# stock.py
+
+from structly.structure import Structure
+
+class Stock(Structure):
+    name = String()
+    shares = PositiveInteger()
+    price = PositiveFloat()
+    
+    @property
+    def cost(self):
+        return self.shares * self.price
+
+    def sell(self, nshares: PositiveInteger):
+        self.shares -= nshares
+
+if __name__ == '__main__':
+    from structly.reader import read_csv_as_instances
+    from structly.tableformat import create_formatter, print_table
+    portfolio = read_csv_as_instances('Data/portfolio.csv', Stock)
+    formatter = create_formatter('text')
+    print_table(portfolio, ['name','shares','price'], formatter)
+```
+
+\[ [Solution](soln9_2.md) | [Index](index.md) | [Exercise 9.1](ex9_1.md) | [Exercise 9.3](ex9_3.md) \]
+
+----
+`>>>` Advanced Python Mastery  
+`...` A course by [dabeaz](https://www.dabeaz.com)  
+`...` Copyright 2007-2023  
+
+![](https://i.creativecommons.org/l/by-sa/4.0/88x31.png). This work is licensed under a [Creative Commons Attribution-ShareAlike 4.0 International License](http://creativecommons.org/licenses/by-sa/4.0/)