day #5 concurrency, file handling

workspace/3_oops/10_exception.py

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+# Exception: An event that interrupts the normal flow of the program's execution.
+# ZeroDivisionError: Occurs when you try to divide by zero.
+# SyntaxError: Occurs when Python encounters incorrect syntax.
+# TypeError: Occurs when you try to combine two objects that are not compatible.
+# ValueError: Occurs when a built-in operation or function receives an argument that has the right type but an inappropriate value.
+#
+# 1. try:, 2. except:, 3. else:, 4. finally:
+
+try:
+    number = int(input("Enter a number: "))
+    print(1/number)
+except ZeroDivisionError:
+    print("You can't divide by zero.")
+except ValueError:
+    print("Please enter a valid number.")
+except Exception:
+    print("Something went wrong.")
+finally:
+    print("This will always run.")

workspace/3_oops/11_1_file_detection.py

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+# Python file detection
+
+import os
+
+# file_path = "workspace/3_oops/test.txt"
+file_path = "workspace/3_oops"
+
+if os.path.exists(file_path):
+    print(f"File exists in {file_path}.")
+
+    if os.path.isfile(file_path):
+        print(f"File is a regular file.")
+    elif os.path.isdir(file_path):
+        print(f"File is a directory.")
+else:
+    print(f"File does not exist in {file_path}.")

workspace/3_oops/11_2_file_writing.py

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+# Python write to files (.txt, .csv, .json)
+
+import csv
+import json
+
+
+text_data = "Hello, World!"
+
+file_path = "workspace/3_oops/output.txt"
+xfile_path = "workspace/3_oops/output_x.txt"
+employees = ["John", "Doe", "Jane", "Doe"]
+
+# w: write, a: append, r: read, x: create
+with open(file_path, "w") as file:
+    file.write(text_data)
+    print(f"Data written to {file_path}.")
+
+try:
+    with open(xfile_path, "x") as file:
+        file.write(text_data)
+        print(f"Data written to {xfile_path}.")
+except FileExistsError:
+    print(f"File already exists in {xfile_path}.")
+
+try:
+    with open(file_path, "a") as file:
+        file.write("\n" +text_data)
+        print(f"Data written to {file_path}.")
+        for employee in employees:
+            file.write("\n" +employee)
+except FileExistsError:
+    print(f"File already exists in {file_path}.")
+
+
+#JSON
+
+jfile_path = "workspace/3_oops/output.json"
+
+student = {
+    "name": "John Doe",
+    "age": 25,
+    "grade": "A"
+}
+
+try:
+    with open(jfile_path, "w") as file:
+        json.dump(student, file, indent=4)
+        print(f"JSON Data written to {jfile_path}.")
+except FileExistsError:
+    print(f"File already exists in {jfile_path}.")
+
+# CSV
+
+students = [["Name", "Age", "Grade"],
+    ["John Doe", 25, "A"],
+    ["Jane Doe", 24, "B"],
+    ["Jim Doe", 23, "C"],
+    ["Jill Doe", 22, "D"]]
+
+cfile_path = "workspace/3_oops/output.csv"
+
+try:
+    with open(cfile_path, "w", newline="") as file:
+        writer = csv.writer(file)
+        for row in students:
+            writer.writerow(row)
+        print(f"CSV Data written to {cfile_path}.")
+
+except FileExistsError:
+    print(f"File already exists in {cfile_path}.")

workspace/3_oops/11_3_file_read.py

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+# Python reading files (.txt, .csv, .json)
+
+import csv
+import json
+
+
+file_path = 'workspace/3_oops/output.txt'
+nfile_path = 'workspace/3_oops/no-exists.txt'
+
+# r= read, w= write, a= append, r+= read and write
+with open(file_path, 'r') as file:
+    content = file.read()
+    print(content)
+
+try:
+    with open(nfile_path, 'r') as file:
+        content = file.read()
+        print(content)
+except FileNotFoundError:
+    print('File not found')
+
+try:
+    with open(file_path, 'r') as file:
+        content = file.read()
+        print(content)
+except FileNotFoundError:
+    print('File not found')
+except PermissionError:
+    print('Permission denied')
+
+# JSON
+jfile_path = 'workspace/3_oops/output.json'
+
+try:
+    with open(jfile_path, 'r') as file:
+        content = json.load(file)
+        print(content)
+        print(content['name'])
+except FileNotFoundError:
+    print('File not found')
+except PermissionError:
+    print('Permission denied')
+
+
+# CSV
+cfile_path = 'workspace/3_oops/output.csv'
+
+try:
+    with open(cfile_path, 'r') as file:
+        content = csv.reader(file)
+        for line in content:
+            print(line)
+            print(line[0])
+            print(line[1])
+except FileNotFoundError:
+    print('File not found')
+except PermissionError:
+    print('Permission denied')
+

workspace/3_oops/12_datetime.py

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+# Python system datetime module
+import datetime
+
+date = datetime.date(2025, 10, 31)
+today = datetime.date.today()
+
+
+print(date) # 2025-10-31
+print(today) # 2025-01-01
+
+
+time = datetime.time(23, 59, 59)
+now = datetime.datetime.now()
+
+nowFormatted = now.strftime("%H:%M:%S %d-%m-%Y")
+
+print(time) # 23:59:59
+print(now) # 2025-01-01 16:49:18.910042
+print(nowFormatted) # 16:49:18 2025-01-01
+
+target_datetime = datetime.datetime(2025, 10, 31, 23, 59, 59)
+current_datetime = datetime.datetime.now()
+
+if target_datetime < current_datetime:
+    print("Target datetime has passed")
+else:
+    print("Target datetime has not passed")

workspace/3_oops/6_class_method.py

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+# Class method: Allowing access to the class from the instance
+#   Take (cls/self) as the first argument, which represents the class itself
+#
+# Instance method: Best for operations on instance of the class (object)
+# Static method: Best for utility functions, which do not require access to the class or instance
+# Class method: Best for class-level operations, which require access to the class, but not the instance
+
+class Employee:
+
+    num_of_emps = 0
+    total_pay = 0
+
+    def __init__(self, name, pay):
+        self.name = name
+        self.pay = pay
+        self.email = name + '@company.com'
+        Employee.num_of_emps += 1
+        Employee.total_pay += pay
+
+    # Instance method
+    def get_info(self):
+        return (f"{self.name}: {self.pay}")
+
+    @classmethod
+    def get_num_of_emps(cls):
+        return (f"Total # of employees: {cls.num_of_emps}")
+
+    @classmethod
+    def get_avg_pay(cls):
+        if cls.num_of_emps == 0:
+            return 0
+
+        return f"Average pay: {cls.total_pay / cls.num_of_emps:0.2f}"
+
+emp1 = Employee('Doe', 6000)
+emp2 = Employee('John', 5000)
+emp3 = Employee('Jane', 7000)
+
+print(Employee.get_num_of_emps())
+print(Employee.get_avg_pay())

workspace/3_oops/7_magic(dunder)_method.py

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+# Magic methods: dunder/double underscore methods
+# __init__, __str__, __eq__
+# These methods are called automatically when certain operations are performed on objects.
+# Allow developers to define custom behavior for objects.
+
+class Book:
+
+    def __init__(self, title, author, pages):
+        self.title = title
+        self.author = author
+        self.pages = pages
+
+    def __str__(self):
+        return (f"'{self.title}' by {self.author}")
+
+    def __eq__(self, other):
+        return self.title == other.title and self.author == other.author
+
+    def __lt__(self, other):
+        return self.pages < other.pages
+
+    def __gt__(self, other):
+        return self.pages > other.pages
+
+    def __add__(self, other):
+        return f"{self.pages + other.pages} pages"
+
+    def __contains__(self, keyword):
+        return keyword in self.title or keyword in self.author
+
+    def __getitem__(self, key):
+        if key == 'title':
+            return self.title
+        elif key == 'author':
+            return self.author
+        elif key == 'pages':
+            return self.pages
+        else:
+            return f"Invalid key: {key}"
+
+book1 = Book('Python', 'John Doe', 210)
+book2 = Book('Python', 'John Doe', 210)
+# book2 = Book('Java', 'Jane Doe', 330)
+book3 = Book('PHP', 'Hacker', 192)
+
+# __str__ method is called automatically when we print the object instead memory address is printed.
+print(book1)
+print(book2)
+print(book3)
+
+# __eq__ method is called automatically when we compare two objects.
+print(book1 == book2)
+print(book2 < book3)
+print(book2 > book3)
+print(book2 + book3)
+
+print("PHP" in book3)
+print("John" in book1)
+
+print(book1['title'])
+print(book1['audio'])

workspace/3_oops/8_@property.py

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+# @property
+# @property is a built-in decorator in Python which is helpful in defining the properties effortlessly without calling the property() function explicitly.
+# Decorator used to dfine a method as a property. (it can be accessed as an attribute instead of a method)
+# Benefits:
+# - Add additional logic when read, write or delete a property
+# - gives you getter, setter, deleter methods
+
+class Reactangle:
+    def __init__(self, width, height):
+        # _width and _height are private variables, they are not accessible from outside the class
+        self._width = width
+        self._height = height
+
+    # Getter
+    @property
+    def width(self):
+        return f"{self._width:.1f}cm"
+
+    @property
+    def height(self):
+        return f"{self._height:.1f}cm"
+
+    # Setter
+    @width.setter
+    def width(self, new_width):
+        if new_width > 0:
+            self._width = new_width
+        else:
+            print("Width must be greater than 0")
+
+    @height.setter
+    def height(self, new_height):
+        if new_height > 0:
+            self._height = new_height
+        else:
+            print("Height must be greater than 0")
+
+
+    # Deleter
+    @width.deleter
+    def width(self):
+        del self._width
+        print("Width has been deleted")
+
+    @height.deleter
+    def height(self):
+        del self._height
+        print("Height has been deleted")
+
+rectangle = Reactangle(10, 20)
+
+rectangle.width = 40
+rectangle.height = 70
+
+del rectangle.width
+del rectangle.height
+
+# print(rectangle.width)
+# print(rectangle.height)

workspace/3_oops/9_decorator.py

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+# Decorator: A function that takes another function as an argument and adds some kind of functionality and returns another function
+# without altering the source code of the original function that is passed as an argument.
+# Pass the base function as an argument to the decorator function and return the modified function.
+#
+#   @add_sprinkles
+#   get_icecream("Vanilla")
+
+def add_sprinkles(func):
+    # wrapper function is needed to avoid calling the function directly
+    def wrapper(*args, **kwargs):
+        print(f"*Adding sprinkles 🎉*")
+        func(*args, **kwargs)
+    return wrapper
+
+def add_fudge(func):
+    def wrapper(*args, **kwargs):
+        print(f"*Adding fudge 🍫*")
+        func(*args, **kwargs)
+    return wrapper
+
+@add_sprinkles
+@add_fudge
+def get_icecream(flavor):
+    print(f"Here is your {flavor} icecream 🍦")
+
+get_icecream("Vanilla")