Update

lectures/3/3.md

@@ -15,16 +15,16 @@ _class: titlepage
 
 ###### Pasquale Claudio Africa, Dario Coscia
 
-###### 14 Feb 2025
+###### 18 Feb 2025
 
 ---
 
 # Outline
 
 1. Scientific data types
 2. The role of Python in modern scientific computing
-3. Dependency management
-4. Error handling
+3. Error handling
+4. Dependency management
 5. Docker
 6. Continuous Integration/Continuous Deployment
 
@@ -484,6 +484,107 @@ _class: titlepage
 _class: titlepage
 -->
 
+# Error handling
+
+---
+
+# Exceptions
+
+If something goes wrong, we don't want our code to crash - we want it to **fail gracefully**. In Python, this can be accomplished using `try`/`except`. Here is a basic example:
+
+```python
+this_variable_does_not_exist
+print("Another line") # Code fails before getting to this line.
+```
+> NameError: name 'this_variable_does_not_exist' is not defined
+
+---
+
+# `try-except`
+
+```python
+try:
+    this_variable_does_not_exist
+except:
+    pass # Do nothing.
+    print("You did something bad! But I won't raise an error.")
+print("Another line")
+```
+
+    You did something bad! But I won't raise an error.
+    Another line
+
+
+Python tries to execute the code in the `try` block. If an error is encountered, we *catch* this in the `except` block (also called `try`/`catch` in other languages). There are many different error types, or **exceptions** - we saw `NameError` above. 
+
+```python
+5 / 0
+```
+> ZeroDivisionError: division by zero
+
+---
+
+# A complete example
+
+```python
+x = 2
+y = 0
+
+try:
+    result = x / y
+except ZeroDivisionError:
+    print("Sorry! You are dividing by zero.")
+else:
+    print("Yeah! Your answer is: ", result)
+finally:
+    # This block is always executed
+    # regardless of exception generation.
+    print('This is always executed')
+```
+
+---
+
+# More exception types
+
+```python
+my_list = [1, 2, 3]
+my_list[5]
+```
+> IndexError: list index out of range
+
+```python
+my_tuple = (1,2,3)
+my_tuple[0] = 0
+```
+> TypeError: 'tuple' object does not support item assignment
+
+---
+
+# Raise exceptions
+
+We can also write code that raises an exception on purpose, using `raise`:
+
+```python
+def add_one(x):
+    if not isinstance(x, float) and not isinstance(x, int):
+        raise TypeError(f"Sorry, x must be numeric, you entered a {type(x)}.")
+        
+    return x + 1
+
+add_one("blah")
+```
+> TypeError: Sorry, x must be numeric, you entered a <class 'str'>.
+
+This is useful when your function is complicated and would fail in a complicated way, with a weird error message. You can make the cause of the error much clearer to the *user* of the function.
+
+Finally, we can even define our own exception types by inheriting from the `Exception` class!
+
+---
+
+<!--
+_class: titlepage
+-->
+
 # Dependency management
 
 ---
@@ -648,107 +749,6 @@ dependencies:
 _class: titlepage
 -->
 
-# Error handling
-
----
-
-# Exceptions
-
-If something goes wrong, we don't want our code to crash - we want it to **fail gracefully**. In Python, this can be accomplished using `try`/`except`. Here is a basic example:
-
-```python
-this_variable_does_not_exist
-print("Another line") # Code fails before getting to this line.
-```
-> NameError: name 'this_variable_does_not_exist' is not defined
-
----
-
-# `try-except`
-
-```python
-try:
-    this_variable_does_not_exist
-except:
-    pass # Do nothing.
-    print("You did something bad! But I won't raise an error.")
-print("Another line")
-```
-
-    You did something bad! But I won't raise an error.
-    Another line
-
-
-Python tries to execute the code in the `try` block. If an error is encountered, we *catch* this in the `except` block (also called `try`/`catch` in other languages). There are many different error types, or **exceptions** - we saw `NameError` above. 
-
-```python
-5 / 0
-```
-> ZeroDivisionError: division by zero
-
----
-
-# A complete example
-
-```python
-x = 2
-y = 0
-
-try:
-    result = x / y
-except ZeroDivisionError:
-    print("Sorry! You are dividing by zero.")
-else:
-    print("Yeah! Your answer is: ", result)
-finally:
-    # This block is always executed
-    # regardless of exception generation.
-    print('This is always executed')
-```
-
----
-
-# More exception types
-
-```python
-my_list = [1, 2, 3]
-my_list[5]
-```
-> IndexError: list index out of range
-
-```python
-my_tuple = (1,2,3)
-my_tuple[0] = 0
-```
-> TypeError: 'tuple' object does not support item assignment
-
----
-
-# Raise exceptions
-
-We can also write code that raises an exception on purpose, using `raise`:
-
-```python
-def add_one(x):
-    if not isinstance(x, float) and not isinstance(x, int):
-        raise TypeError(f"Sorry, x must be numeric, you entered a {type(x)}.")
-        
-    return x + 1
-
-add_one("blah")
-```
-> TypeError: Sorry, x must be numeric, you entered a <class 'str'>.
-
-This is useful when your function is complicated and would fail in a complicated way, with a weird error message. You can make the cause of the error much clearer to the *user* of the function.
-
-Finally, we can even define our own exception types by inheriting from the `Exception` class!
-
----
-
-<!--
-_class: titlepage
--->
-
 # Introduction to Docker
 
 ---
@@ -982,7 +982,7 @@ jobs:
 
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v2
+      uses: actions/checkout@v3
 
     - name: Set up Python environment
       run: |
@@ -1013,7 +1013,7 @@ jobs:
         sphinx-build -b html . _build/html
 
     - name: Upload documentation
-      uses: actions/upload-artifact@v2
+      uses: actions/upload-artifact@v3
       with:
         name: documentation
         path: docs/_build/html/