Skip to content

Commit

Permalink
Add a "scripting" reading exercise
Browse files Browse the repository at this point in the history
  • Loading branch information
MaybeJustJames committed Sep 11, 2024
1 parent b7255f5 commit d95da36
Show file tree
Hide file tree
Showing 2 changed files with 63 additions and 0 deletions.
14 changes: 14 additions & 0 deletions dodona/reading-exercises/scripts/config.json
Original file line number Diff line number Diff line change
@@ -0,0 +1,14 @@
{
"description": {
"names": {
"en": "Scripting"
}
},
"labels": [
"real-world programming"
],
"internals": {
"token": "X5rVj9e4R7tbj4SxX78RXrS93eTq5CkKfT6HWTJrer2I-N33yqry9dj-nSRfzHct",
"_info": "These fields are used for internal bookkeeping in Dodona, please do not change them."
}
}
49 changes: 49 additions & 0 deletions dodona/reading-exercises/scripts/description/description.en.md
Original file line number Diff line number Diff line change
@@ -0,0 +1,49 @@
When you write a program for yourself (or download a Python program from the internet), you will
probably want to run it sooner or later.

This is quite straightforward. You can simply follow these steps:
* Open the terminal program you use (on Windows this might be called "Power Shell" or "CMD"),
* Navigate to the folder where the program is stored,
* Run the program by typing `python my_cool_program.py` (also known as running a "script").

There is an important problem when building programs that you should be aware of: any top-level code
always runs when you run the script **BUT ALSO** at _import_ time. That's right! You can `import`
your program too.

This is a problem because, you probably don't expect to be running Python code just because you
`import`ed something. To avoid this you can use a trick to check if your code is being run as a script
or if it's being imported.

There is a special variable that Python gives you called `__name__` which is the name of the current
module. Try this in your own programming environment if you like: create 2 files.

A file "a.py" should contain:
```python
print("__name__ is: ", __name__)
```

A file "b.py" should contain:
```python
import a
print("I'm in b")
```

Now run `python a.py` (Use a.py as a script, not importing it). This should be printed to the console:
```
__name__ is: __main__
```

And if you run `python b.py` (Import a.py). This should print:
```
__name__ is: a
I'm in b
```

Notice that the special variable `__name__` contains `"__main__"` when you run the file as a script.
So when you define code to run when using your program as a script you should use this construction:
```python
if __name__ == "__main__":
# code to run when using my program as a script.

```

0 comments on commit d95da36

Please sign in to comment.