Code Quality
Global Variables in Python: Why They Cause Bugs
Global variables create hidden dependencies that make code hard to test and reason about. When any function can modify a global, the program's state becomes unpredictable.
❌ Problematic Global State
user_count = 0
def register_user(name):
global user_count
user_count += 1
print(f'Registered {name}, total: {user_count}')
def reset():
global user_count
user_count = 0 # Silent side effect!✅ Refactored as Class
class UserRegistry:
def __init__(self):
self._count = 0
def register(self, name):
self._count += 1
print(f'Registered {name}, total: {self._count}')
def reset(self):
self._count = 0💡
Pro tip: Encapsulate state in a class or pass it as function parameters. This makes dependencies visible, testable, and replaceable.
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