What are the best practices for using mutable data in Ruby?

What are the best practices for using mutable data in Ruby?

When using mutable data in Ruby, it's important to be cautious to avoid unintended side effects. Here are some best practices:

1. Use freeze: Call freeze on objects that should not be modified.
2. Duplication: Use dup or clone to create copies of mutable objects when passing them around.
3. Immutability: Prefer immutable data structures when possible, like using Struct or OpenStruct for fixed data.
4. Clear documentation: Document methods that modify data to inform users of potential side effects.

Can you explain why using freeze is important?

Using freeze is important because it prevents an object from being modified. This is crucial in maintaining the integrity of data, especially when passing objects around in your code. If an object is frozen, any attempt to modify it will raise a FrozenError, helping you catch bugs early.

What are some common pitfalls when working with mutable data?

Common pitfalls include:

1. Unintended modifications: Passing mutable objects to methods can lead to unexpected changes.
2. Shared state: Multiple references to the same mutable object can cause issues if one reference modifies it.
3. Performance issues: Excessive duplication of large mutable objects can lead to performance degradation.

How can I ensure my methods are safe to use with mutable data?

To ensure your methods are safe with mutable data, you can:

1. Use defensive copying: Always work with copies of mutable objects.
2. Document side effects: Clearly state in your method documentation if the method modifies its arguments.
3. Limit scope: Keep mutable data within a limited scope to reduce the risk of unintended changes.