Complete exercises for Module Tools/Sprint 5/Prep - step 7 'Type-guided refactorings'

Author: Geraldine-Edwards

prep-exercises/g_type_guided_refactorings.py

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+from dataclasses import dataclass
+from typing import List
+
+# @dataclass(frozen=True)
+# class Person:
+#     name: str
+#     age: int
+#     preferred_operating_system: str
+
+
+# @dataclass(frozen=True)
+# class Laptop:
+#     id: int
+#     manufacturer: str
+#     model: str
+#     screen_size_in_inches: float
+#     operating_system: str
+
+
+# def find_possible_laptops(laptops: List[Laptop], person: Person) -> List[Laptop]:
+#     possible_laptops = []
+#     for laptop in laptops:
+#         if laptop.operating_system == person.preferred_operating_system:
+#             possible_laptops.append(laptop)
+#     return possible_laptops
+
+
+# people = [
+#     Person(name="Imran", age=22, preferred_operating_system="Ubuntu"),
+#     Person(name="Eliza", age=34, preferred_operating_system="Arch Linux"),
+# ]
+
+# laptops = [
+#     Laptop(id=1, manufacturer="Dell", model="XPS", screen_size_in_inches=13, operating_system="Arch Linux"),
+#     Laptop(id=2, manufacturer="Dell", model="XPS", screen_size_in_inches=15, operating_system="Ubuntu"),
+#     Laptop(id=3, manufacturer="Dell", model="XPS", screen_size_in_inches=15, operating_system="ubuntu"),
+#     Laptop(id=4, manufacturer="Apple", model="macBook", screen_size_in_inches=13, operating_system="macOS"),
+# ]
+
+# for person in people:
+#     possible_laptops = find_possible_laptops(laptops, person)
+#     print(f"Possible laptops for {person.name}: {possible_laptops}")
+
+
+# ------------------------
+# Exercise 1
+# ------------------------
+# Try changing the type annotation of Person.preferred_operating_system from str to List[str].
+# Run mypy on the code.
+# It tells us different places that our code is now wrong, because we’re passing values of the wrong type.
+# We probably also want to rename our field - lists are plural. Rename the field to preferred_operating_systems.
+# Run mypy again.
+# Fix all of the places that mypy tells you need changing. Make sure the program works as you’d expect.
+
+@dataclass(frozen=True)
+class Person:
+    name: str
+    age: int
+    preferred_operating_systems: List[str]
+
+
+@dataclass(frozen=True)
+class Laptop:
+    id: int
+    manufacturer: str
+    model: str
+    screen_size_in_inches: float
+    operating_system: str
+
+# avoid variable shadowing my changing the internal variable names so that they don't confuse the reader
+def find_possible_laptops(available_laptops: List[Laptop], current_person: Person) -> List[Laptop]:
+    matching_laptops = []
+    for laptop in available_laptops:
+        if laptop.operating_system in current_person.preferred_operating_systems:
+            matching_laptops.append(laptop)
+    return matching_laptops
+
+
+people = [
+    Person(name="Imran", age=22, preferred_operating_systems=["Ubuntu"]),
+    Person(name="Eliza", age=34, preferred_operating_systems=["Arch Linux"]),
+]
+
+laptops = [
+    Laptop(id=1, manufacturer="Dell", model="XPS", screen_size_in_inches=13, operating_system="Arch Linux"),
+    Laptop(id=2, manufacturer="Dell", model="XPS", screen_size_in_inches=15, operating_system="Ubuntu"),
+    Laptop(id=3, manufacturer="Dell", model="XPS", screen_size_in_inches=15, operating_system="ubuntu"),
+    Laptop(id=4, manufacturer="Apple", model="macBook", screen_size_in_inches=13, operating_system="macOS"),
+]
+
+for person in people:
+    possible_laptops = find_possible_laptops(laptops, person)
+    print(f"Possible laptops for {person.name}: {possible_laptops}")