What are the limitations of using defaultdict in Python?

What are the limitations of using defaultdict in Python?

While defaultdict is very useful, it has some limitations. For instance, it can lead to unexpected behavior if you're not careful with the default factory.

Can you give an example of unexpected behavior?

Sure! If you use a list as the default factory, accessing a key that doesn't exist will create an empty list, which might not be what you intended.

Are there performance issues with defaultdict?

Generally, defaultdict is efficient, but if you're using a complex factory function, it might introduce overhead compared to a regular dictionary.

When should I avoid using defaultdict?

You might want to avoid defaultdict when you need strict control over key initialization or when using it could lead to confusion in your code.