--- marp: true theme: default html: true --- # Modules Python functions and events · Functions --- ## Today **We are learning to** keep related functions together in a file you can import, like a toolbox. - I can import functions from a module and use them. - I can explain why one shared module is easier to fix than copies of the same code. - I can move related functions into a module of my own. --- ## Why it matters > Every Python program you will ever use imports other people's modules. Now you will build your own. --- 💬 Discussion ## Predict ```python from turtle import * from shapes import square, triangle square(80) triangle(80) ``` This program never defines `square` or `triangle`. What does it draw? Where do you think they come from? --- ✍️ Activity ## Run it {{embed: https://studio.learningwaypoints.com/tutorials/_playground/index.html?code=from+turtle+import+*%0Afrom+shapes+import+square%2C+triangle%0A%0Asquare%2880%29%0Atriangle%2880%29%0A}} _If it does not load:_ [open this step in the tutorial](https://studio.learningwaypoints.com/tutorials/code/python-functions/turtle-modules/?full=step-2#step-2) --- ✅ Check ## Every line to change **The walls do not close: the turn inside wall is wrong. Click every line you would have to change.**
**program_a.py** ``` 1 from turtle import * 2 3 4 def wall(size): 5 for i in range(4): 6 forward(size) 7 right(80) 8 9 10 wall(60) ```
**program_b.py** ``` 1 from turtle import * 2 3 4 def wall(size): 5 for i in range(4): 6 forward(size) 7 right(80) 8 9 10 wall(100) ```
* Answer: line program_a.py:7 and program_b.py:7 --- ✅ Check ## Count the fixes **You fix the bug in program_a.py. What happens to program_b.py?** - It still has the bug, so you fix it separately - It stops working - Python warns you - It is fixed too * Answer: It still has the bug, so you fix it separately --- 💬 Discussion ## Investigate: where does it come from? ```python from turtle import * from shapes import square, triangle square(80) triangle(80) ``` --- ✅ Check ## Find the def
```python from turtle import * from shapes import square, triangle square(80) triangle(80) ```
**Where is square defined?** - Nowhere - In shapes.py, which this program imports - In this program - Inside the turtle module * Answer: In shapes.py, which this program imports
--- ✅ Check ## Same name twice ```python # file: shapes.py from turtle import * def square(size): for i in range(4): forward(size) right(90) # file: main.py from turtle import * from shapes import square def square(size): circle(size / 2) square(80) ``` **main.py imports square, then defines its own square. What does square(80) draw?** - A square and a circle - A square, from shapes.py - A circle, from main.py - Nothing: Python stops with an error * Answer: A circle, from main.py --- ✍️ Activity ## Modify These three functions are all in one file, and the wall does not close. Click **+ module**, move them into it, and import `house` back into `main.py`. Then fix the turn in `wall`, once, in the module. Work it out from the shape, as you did with variables: `360 / 4`, not a guessed number. --- ✍️ Activity ## Live: Modify {{embed: https://studio.learningwaypoints.com/tutorials/_playground/index.html?code=from+turtle+import+*%0A%0A%0Adef+wall%28size%29%3A%0A++++for+i+in+range%284%29%3A%0A++++++++forward%28size%29%0A++++++++right%2880%29%0A%0A%0Adef+roof%28size%29%3A%0A++++left%2860%29%0A++++forward%28size%29%0A++++right%28120%29%0A++++forward%28size%29%0A++++right%28120%29%0A++++forward%28size%29%0A++++right%28180%29%0A%0A%0Adef+house%28size%29%3A%0A++++wall%28size%29%0A++++roof%28size%29%0A%0A%0Ahouse%2860%29%0A}} _If it does not load:_ [open this step in the tutorial](https://studio.learningwaypoints.com/tutorials/code/python-functions/turtle-modules/?full=step-5#step-5) --- ✅ Check ## Mix it up **How far does the turtle draw in total, counting only the lines (not the turns)?** * Answer: 320 --- ✍️ Activity ## Make Create a module of your own with at least three related functions. Import it and use it to draw a small scene. --- ✍️ Activity ## Live: Make {{embed: https://studio.learningwaypoints.com/tutorials/_playground/index.html?code=from+turtle+import+*%0A%0A%23+Create+a+module+of+your+own+with+several+functions%2C+then+import+it+here+and+use+it.%0A}} _If it does not load:_ [open this step in the tutorial](https://studio.learningwaypoints.com/tutorials/code/python-functions/turtle-modules/?full=step-7#step-7) --- ✍️ Activity ## Extend a street A street is a few buildings repeated, and each building comes from a module. Run it. Add a roof colour, a taller house, or a gap in the street. You are changing the plan without rewriting any of the shapes. --- ✍️ Activity ## Live: Extend a street {{embed: https://studio.learningwaypoints.com/tutorials/_playground/index.html?code=from+turtle+import+*%0Afrom+shapes+import+square%2C+triangle%0A%0Afor+i+in+range%284%29%3A%0A++++square%2860%29%0A++++triangle%2860%29%0A++++penup%28%29%0A++++forward%2880%29%0A++++pendown%28%29%0A}} _If it does not load:_ [open this step in the tutorial](https://studio.learningwaypoints.com/tutorials/code/python-functions/turtle-modules/?full=step-8#step-8) --- ✅ Check ## Exit ticket **Two programs each have their own copy of a draw_tree function with a bug. Why would putting draw_tree in a module be better?** * Both programs would import the one function, so fixing it once in the module fixes it for both.