Glasgow | 26-Jul-SDC | Shreef Ibrahim | Sprint 5 | Prep Exercises

sprint5-prep-exercises/LimiOfTypeCheck.py

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+def double(number):
+    # return number * 3
+    return number * 2
+
+print(double(10))
+# The bug is that the double function multiplies the number by 3 instead of 2.
+#  Since the function is called double, it should multiply the number by 2. 

sprint5-prep-exercises/PredictInheritance.py

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+# Parent class stores a person's first name and last name
+class Parent:
+    def __init__(self, first_name: str, last_name: str):
+        self.first_name = first_name
+        self.last_name = last_name
+    # Returns the person's first and last name together
+    def get_name(self) -> str:
+        return f"{self.first_name} {self.last_name}"
+
+# Child inherits the fields and methods from Parent
+# It also allows the person to change their last name
+class Child(Parent):
+    def __init__(self, first_name: str, last_name: str):
+        super().__init__(first_name, last_name)
+        self.previous_last_names = []
+    # Changes the last name and saves the old name
+    def change_last_name(self, last_name) -> None:
+        self.previous_last_names.append(self.last_name)
+        self.last_name = last_name
+   # Returns the current name and the original last name
+    def get_full_name(self) -> str:
+        suffix = ""
+        if len(self.previous_last_names) > 0:
+            suffix = f" (née {self.previous_last_names[0]})"
+        return f"{self.first_name} {self.last_name}{suffix}"
+# Create child object
+person1 = Child("Elizaveta", "Alekseeva")
+# Child inherits get_name() from Parent
+# Output: Elizaveta Alekseeva
+print(person1.get_name())
+# Child has its own get_full_name() method
+# Output: Elizaveta Alekseeva
+print(person1.get_full_name())
+# Change the last name 
+person1.change_last_name("Tyurina")
+# The current last name is now Tyurina
+# Output: Elizaveta Tyurina
+print(person1.get_name())
+# Shows the new name and the previous last name
+# Output: Elizaveta Tyurina (née Alekseeva)
+print(person1.get_full_name())
+# Create a Parent object
+person2 = Parent("Elizaveta", "Alekseeva")
+# Parent has get_name(), so this works
+# Output: Elizaveta Alekseeva
+print(person2.get_name())
+# This causes an AttributeError because Parent
+# does not have a get_full_name() method
+print(person2.get_full_name())
+# This also causes an AttributeError because Parent
+# does not have a change_last_name() method
+person2.change_last_name("Tyurina")
+# get_name() still works because it belongs to Parent
+# Output: Elizaveta Alekseeva
+print(person2.get_name())
+# This would cause another AttributeError
+# because get_full_name() only exists in Child
+print(person2.get_full_name())

sprint5-prep-exercises/accessNotExiProp.py

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+class Person:
+    def __init__(self, name: str):
+        self.name = name
+
+def get_name(person: Person) -> str:
+    return person.name
+
+def get_age(person: Person) -> int:
+    return person.age
+# As I expected, mypy prints an error saying that Person has no attribute name,
+#  because the age property does not exist in the Person class.

sprint5-prep-exercises/classesAndObjects.py

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+class Person:
+    def __init__(self, name: str, age: int, preferred_operating_system: str):
+        self.name = name
+        self.age = age
+        self.preferred_operating_system = preferred_operating_system
+
+imran = Person("Imran", 22, "Ubuntu")
+print(imran.name)
+print(imran.address)
+
+eliza = Person("Eliza", 34, "Arch Linux")
+print(eliza.name)
+print(eliza.address)
+
+
+# The error means that address doesn't exist in the Person class. We can only 
+# access attributes that were defined in the class, such as name, age, and preferred_operating_system.

sprint5-prep-exercises/enums.py

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+from dataclasses import dataclass
+from enum import Enum
+import sys
+
+
+class OperatingSystem(Enum):
+    MACOS = "macOS"
+    ARCH = "Arch Linux"
+    UBUNTU = "Ubuntu"
+
+
+@dataclass(frozen=True)
+class Person:
+    name: str
+    age: int
+    preferred_operating_system: OperatingSystem
+
+
+@dataclass(frozen=True)
+class Laptop:
+    id: int
+    manufacturer: str
+    model: str
+    screen_size_in_inches: float
+    operating_system: OperatingSystem
+
+
+laptops = [
+    Laptop(1, "Dell", "XPS", 13, OperatingSystem.ARCH),
+    Laptop(2, "Dell", "XPS", 15, OperatingSystem.UBUNTU),
+    Laptop(3, "Dell", "XPS", 15, OperatingSystem.UBUNTU),
+    Laptop(4, "Apple", "MacBook", 13, OperatingSystem.MACOS),
+]
+
+
+# Get the person's name
+name = input("What is your name? ")
+
+
+# Get and convert age
+try:
+    age = int(input("What is your age? "))
+except ValueError:
+    print("Age must be a number.", file=sys.stderr)
+    sys.exit(1)
+
+
+# Get and convert operating system
+try:
+    os_input = input("What is your preferred operating system? ")
+    operating_system = OperatingSystem(os_input)
+except ValueError:
+    print("Invalid operating system.", file=sys.stderr)
+    sys.exit(1)
+
+
+person = Person(
+    name=name,
+    age=age,
+    preferred_operating_system=operating_system,
+)
+
+
+# Count laptops with the person's preferred OS
+number_available = sum(
+    laptop.operating_system == person.preferred_operating_system
+    for laptop in laptops
+)
+
+
+print(
+    f"We have {number_available} laptop(s) with "
+    f"{person.preferred_operating_system.value}."
+)
+
+
+# Find the operating system with the most laptops
+counts = {}
+
+for os in OperatingSystem:
+    counts[os] = sum(
+        laptop.operating_system == os
+        for laptop in laptops
+    )
+
+
+most_available_os = max(counts, key=counts.get)
+
+
+if most_available_os != person.preferred_operating_system:
+    if counts[most_available_os] > number_available:
+        print(
+            f"If you are willing to use {most_available_os.value}, "
+            f"you are more likely to get a laptop because we have "
+            f"{counts[most_available_os]} available."
+        )

sprint5-prep-exercises/methods.py

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+import datetime as dt
+from dataclasses import dataclass
+
+
+@dataclass
+class Person:
+    name: str
+    birthdate: dt.date
+    preferred_operating_system: str
+
+    def is_adult(self) -> bool:
+        today = dt.date.today()
+        age = today.year - self.birthdate.year
+
+        if (today.month, today.day) < (self.birthdate.month, self.birthdate.day):
+            age -= 1
+
+        return age >= 18
+
+
+imran = Person("Imran", dt.date(2000, 8, 6), "Ubuntu")
+
+print(imran.is_adult())

sprint5-prep-exercises/predictDouble.py

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+def half(value):
+    return value / 2 
+
+def double(value):
+    return value * 2 
+
+def second(value):
+    return value[1]
+
+
+print(double("22"))
+# I predicted that it would return an error, but it actually returned 2222.
+#  I didn't expect this because I thought double() was supposed to work only with numbers.

sprint5-prep-exercises/prefOperatingSys.py

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+from dataclasses import dataclass
+from typing import List
+
+@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
+
+
+def find_possible_laptops(laptops: List[Laptop], person: Person) -> List[Laptop]:
+    possible_laptops = []
+    for laptop in laptops:
+        if laptop.operating_system == person.preferred_operating_systems:
+            possible_laptops.append(laptop)
+    return possible_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}")
+
+
+
+    # Yes, at first, when I changed str to list[str],
+    #  mypy showed errors as I expected because I was still passing strings instead of lists
+    # Then I changed the field name to the plural form `preferred_operating_systems` to match the fact that it is now a list.

sprint5-prep-exercises/typeAnnotations.py

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+
+def open_account(balances: dict[str, int], name: str, amount: int):
+    balances[name] = amount
+
+
+def sum_balances(accounts: dict[str, int]) -> int:
+    total = 0
+    for name, pence in accounts.items():
+        print(f"{name} had balance {pence}")
+        total += pence
+    return total
+
+
+def format_pence_as_string(total_pence: int) -> str:
+    if total_pence < 100:
+        return f"{total_pence}p"
+    pounds = int(total_pence / 100)
+    pence = total_pence % 100
+    return f"£{pounds}.{pence:02d}"
+
+
+balances: dict[str, int] = {
+    "Sima": 700,
+    "Linn": 545,
+    "Georg": 831,
+}
+
+
+open_account(balances, "Tobi", 913)
+open_account(balances, "Olya", 713)
+
+total_pence = sum_balances(balances)
+total_string = format_pence_as_string(total_pence)
+
+print(f"The bank accounts total {total_string}")
+def is_adult(person: Person) -> bool:
+    return person.age >= 18
+
+print(is_adult(imran))