# Code Smell 95 - Premature Classification

*We are over generalizers. We shouldn't create abstractions until we see enough concretions.*

> TL;DR: Don't guess what the future will bring you.

# Context

Aristotelian Classification is a big problem in computer science. 
We tend to classify and name things **before** gathering enough knowledge and context.

# Problems

- Futurology

- Bad designs

# Solutions

1. Wait for concretions

2. Refactor late

# Sample Code

## Wrong

[Gist Url]: # (https://gist.github.com/mcsee/e6ca123df9f10f291a92e863bf168cc0)
```java
class Rectangle 
 { 
       int length; 
       int breadth; 
       
       int area() 
       {
         return length * breadth;
       } 
 } 
//We are creating a premature abstraction 
//And misusing is-a relation since a Square "is a" Rectangle

class Square extends Rectangle
 { 
       int length;  
       
       int area() 
       {  
         return length * length; 
       } 
 } 
```

## Right

[Gist Url]: # (https://gist.github.com/mcsee/d3232090ebc0c1360c85dd1079aebe14)
```java
class Rectangle 
 { 
       int length; 
       int breadth; 
       
       int area() 
       {
         return length * breadth;
       } 
 }  

class Square 
{ 
       int length;  
       
       int area() 
       {  
         return length * length; 
       } 
 } 
//Square might-be a Rectangle
//But it does not follow behaves-like relation so we won't go ahead
//and create a strong relation between them
//Maybe they are shapes. We don't have enough examples and protocol yet
//We will not guess until further knowledge

```

# Detection

An abstract class with just one subclass is an indicator of premature classification

# Tags

- Bad Design 

- Classification

# Conclusion

When working with classes, we name abstractions as soon as they *appear*. 

Our rule is to choose [good names](https://maximilianocontieri.com/what-exactly-is-a-name-part-i-the-quest) after the behaviour.

We should not name our abstractions until we name our concrete subclasses.

# Relations

%[https://maximilianocontieri.com/code-smell-11-subclassification-for-code-reuse]

# More Info

- [What is in a name](https://maximilianocontieri.com/what-exactly-is-a-name-part-i-the-quest)

# Credits

Photo by <a href="https://unsplash.com/@fcornish">Faye Cornish</a> on <a href="https://unsplash.com/s/photos/tree">Unsplash</a>
  
* * *

> Let us change our traditional attitude to the construction of programs: Instead of imagining that our main task is to instruct a computer what to do, let us concentrate rather on explaining to human beings what we want a computer to do.

_Donald E. Knuth_
 
%[https://maximilianocontieri.com/software-engineering-great-quotes]

* * *

This article is part of the CodeSmell Series.

%[https://maximilianocontieri.com/how-to-find-the-stinky-parts-of-your-code]