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Lesson 5 - Writing Reusable and Self-explanatory Programs

Ch2 Shortcut Assignments

• Swapping x, y = y, x
• Augmented assignment operators
  • +=, -=, *=, /=, //=, %=, **=

Ch4 Refactoring

• Break down program into smaller, manageable, and reusable chunks
• Chunks should be independent
• Function naming
  • Verb phrases
    • Indicates return value (bools)
      • has_something
      • is_something
• Top down approach to designing the program
• One function should focus on one thing

Ch5 Advanced Function Features

• Default arguments, so that users don't have to explicitly provide a value for everything
  • Non-default followed by default
• Keyword arguments, specify which default value to override
• Multiple returns
  • Returns a Tuple object
    • Made up of more than one basic object

Ch6 Function Scope

• Any variables created inside a function is local to the function
  • Can't be seen or used outside the function definition
• Global scope
  • When the program is ran
    • Python gives you a box named global (officially named stack frames)
    • Every name (including functions) will be put into the box
    • List of names in each box is called the namespace
• Local scope
  • When python identifies a function
    • A new local box is created
      • Local to the function
    • Global will be made as the new box's parent
      • Since the function is defined in the global namespace
• Finding variables
  • If a name is not found in the local namespace
    • Python will go to the global namespace to fetch the name

Ch7 Styling

• lowercase_with_underscores()
• Use verbs / verb phrases for names
• No spaces before parenthesis
• No spaces around =
• Surround top-level function definition with 2 blank lines
• Indentation
  • Align with opening bracket
  • Next line, one tab over
• Returns
  • Function must return an expression or never return an expression
• Docstrings
  • Google style

    """Summary line.

    Extended description of function.

    Args:
        arg1 (int): Description of arg1
        arg2 (str): Description of arg2

    Returns:
        bool: Description of return value
    """

Ch8 Git Branch

• A branch is a pointer to the last commit
• Can have multiple branches in one repo
  • Each with its own name
• The head indicates which branch you are on
• To create a branch
  • git branch branch_name
• To rename a branch from master to main
  • git branch -m master main
• Always default to main
  • git config --global init.defaultBranch main
• Switching branches
  • git checkout branch_name
• Visual branches
  • git log --oneline --all --graph
• Merge branches
  • Checkout to the branch to be merged into
    • git checkout main
  • Merge
    • git merge branch_name -m "message"

Ch10 Assert Statement

• Makes sure condition is true
  • Stop the program with an error message
• Defensive programming