How to Use Dynamic Variables in Python Safely With Examples and Alternatives

 

 What Are Dynamic Variables?

Dynamic variables refer to variables whose names or values are generated at runtime, not hard-coded. Python allows this using dictionaries, setattr(), or globals()/locals().

 Warning First

Using dynamic variable names via globals() or locals() is not recommended for most use cases because:

• It's hard to debug
• Makes code harder to read and maintain
• Introduces security risks in some cases

 Instead, prefer using dictionaries or objects.

 Recommended: Use a Dictionary

variables = {}

for i in range(3):
    variables[f"var{i}"] = i * 10

print(variables["var0"])  # Output: 0
print(variables["var1"])  # Output: 10

Using setattr() on Objects or Classes

class DynamicVars:
    pass

obj = DynamicVars()

for i in range(3):
    setattr(obj, f"var{i}", i * 100)

print(obj.var0)  # Output: 0
print(obj.var1)  # Output: 100

 Not Recommended: Using globals() or locals()

for i in range(3):
    globals()[f"var{i}"] = i

print(var0)  # Output: 0
print(var1)  # Output: 1

This works, but is discouraged because it pollutes the global namespace.

 Checking If a Dynamic Variable Exists

With hasattr():

if hasattr(obj, "var1"):
    print("var1 exists")

With in for dictionary:

if "var1" in variables:
    print("var1 exists")

 Summary Table

Method	Safe?	Use Case
dict	✅✅	Best for dynamic key-value storage
setattr()	✅	When working with objects or configs
globals()/locals()	⚠️❌	Avoid unless absolutely necessary

 Real Use Cases

• Dynamic form input handling
• Generating config objects dynamically
• Template rendering engines
• Storing user sessions or settings

 Conclusion

While Python allows creating variables dynamically, the safest and cleanest way is to use dictionaries or object attributes via setattr(). Avoid globals() unless you're doing metaprogramming or debugging tools.