> For the complete documentation index, see [llms.txt](https://xiaoyang-liu.gitbook.io/programming-notes/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://xiaoyang-liu.gitbook.io/programming-notes/software-engineering/refactoring/code-smells/dispensables.md).

# Dispensables

A dispensable is something pointless and unneeded whose absence would make the code cleaner, more efficient and easier to understand.

## Comments

A method is filled with explanatory comments. If you feel that a code fragment can’t be understood without comments, try to change the code structure in a way that makes comments unnecessary. **The best comment is a good name for a method or class.**

However, comments can be useful when explaining why something is being implemented in a particular way or complex algorithms.

### Treatment

* Extract Variable
* Extract Method
* Rename Method
* Introduce Assertion

## Duplicate Code

Two code fragments look almost identical.

### Treatment

* Extract Variable
* Extract Method

## Lazy Class

Understanding and maintaining classes always costs time and money. So if a class doesn’t do enough to earn your attention, it should be deleted.

### Treatment

* Inline Class
* Collapse Hierarchy

## Data Class

A data class refers to a class that contains only fields and crude methods for accessing them (getters and setters). These are simply containers for data used by other classes.

## Dead Code

A variable, parameter, field, method or class is no longer used (usually because it’s obsolete).

### Treatment

* Delete unused code and unneeded files.
* Inline Class or Collapse Hierarchy can be applied if a subclass or superclass is used.
* To remove unneeded parameters, use Remove Parameter.

## Speculative Generality

There’s an unused class, method, field or parameter.