Variables: Naming Values

• Naming Guidelines:
  • Must start with a letter or underscore (_) and can contain letters, numbers, and underscores.
  • Use snake_case for readability (e.g., max_retries).
• Purpose: Store data like file paths, server counts, status messages, API keys, configurations.
• Typing: Python uses dynamic typing, which means we don't need to explicitly declare the variable type, and we can assign values with different types to the same variable (not recommended!)

var1 = "hello"

item = 101
print(type(item))

# Never do that! Don't assign a value of a different type to the same variable!
item = "Code 101"
print(type(item))

Comments

Python code may be readable, but comments and docstrings explain intent, rationale, and usage. Comments (#) are ignored by the interpreter; docstrings ("""...""") are accessible via __doc__ (we'll come back to docstrings later, when we discuss functions).

Single-Line Comments (#)

Use # to comment single lines or inline code. Best for explaining why, adding TODO/FIXME markers, or temporarily disabling code.

# Example of a single-line comment
error_code = 0

# TODO: handle case when argument is None 

Multi-Line / Block Comments

Prefix each line with # to comment out blocks of code. Useful for disabling sections or annotating complex logic. It's also possible to wrap multiline comments between triple single-quotes ('''...''') or between triple double-quotes ("""..."""), but this is not their original intended usage.

# if True:
#     print("I will execute")