# Parallel Inheritance Hierarchies

> Two or more class hierarchies that grow in parallel.

- **Category**: Code Smells
- **Subcategory**: change-preventers
- **Canonical URL**: https://designpattern.fyi/code_smells/parallel-hierarchies/

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## Description
'**Intent**: Identify when you have to make changes to multiple inheritance hierarchies simultaneously.

**Context**: Creating a subclass in one hierarchy requires creating a corresponding subclass in another hierarchy.

**Solution**: Merge the hierarchies or eliminate the dependency between them using composition.'



## Use Cases
Use when adding a class to one hierarchy requires changes to another.









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**Reference**: [Original Source](https://refactoring.guru/smells/parallel-inheritance-hierarchies)