# Code Smell 237 - Attribute Definitions

> TL;DR: Never focus on implementation. Focus on behavior instead.

# Problems

- Coupling to implementation

- Lack of Separation between the ['What' and the 'How'](https://maximilianocontieri.com/code-smell-123-mixed-what-and-how)

- Encapsulation and Information Hiding violations

- Lack of Abstraction

- Unclear separation of Interfaces/Protocol

- Coupled Testability

- Debugging using inspectors instead of sending messages to objects.

# Solutions

1. Redesign your favorite programming language

2. Ignore the (accidental) implementation and study the available protocol

# Context

For historical reasons, most class-based programming languages declare the attributes first and the public protocol after.

This is a problem if you need to understand what a class does at first sight.

Some languages implemented [Header files](https://simple.wikipedia.org/wiki/Header_file) (often denoted by the .h extension).

They contain declarations of functions, classes, variables, and other constructs without providing the full implementation.

These files serve as a way to share information about the structure and interface of a program or library across multiple source code files.

# Sample Code

## Wrong

[Gist Url]: # (https://gist.github.com/mcsee/4e5896ea95b0115f6f3dfb3571dc827a)
```java
public class ShoppingCart {
  
    // This is Accidental
    private List<Item> items;

    // This is Also Accidental
    // And irrelevant to cart usage
    public ShoppingCart() {
        this.items = new ArrayList<>();
    }
 
    public void addItem(Item item) {
        items.add(item); 
    }
 
    public void removeItem(Item item) {
        // Error handling is irrelevant for the example
        items.remove(item);
    }
 
    public double calculateTotal() {
        double total = 0.0;
        for (Item item : items) {
            total += item.getPrice();
        }
        return total;
    }
}
```

## Right

[Gist Url]: # (https://gist.github.com/mcsee/e4aec099dfea90daba8ce073baf626db)
```java
public class ShoppingCart {
     
    // Focus on public behavior only    
    // This is invalid in Java :(
    public ShoppingCart() { } 
    public void addItem(Item item) { }  
    public void removeItem(Item item) { }     
    public double calculateTotal() {}
}
```

# Detection

[X] Manual

This is language smell. You cannot detect it.

# Exceptions

- This smell applies only to languages requiring explicit attribute definitions like Java, C#, PHP, etc.

Dynamically-typed languages like Python or JavaScript do not require explicit attribute definition. 

In these languages, you can create attributes on the fly without declaring them in the class definition. 

# Tags

- Hierarchies

# Level

[X] Beginner 

# AI Assistants

Most AI Assistants generate code with this smell.

Try prompting: 'Generate a class representing a House in Java'

# Conclusion

You cannot change the language you use, still, according to The [Sapir-Whorf hypothesis](https://learning.oreilly.com/library/view/clean-code-cookbook/9781098144715/) the structure and vocabulary of a language can shape or influence how its speakers perceive and think about the real world using the [MAPPER](https://maximilianocontieri.com/what-is-wrong-with-software).

# Relations

%[https://maximilianocontieri.com/code-smell-123-mixed-what-and-how]

# More Info

%[https://simple.wikipedia.org/wiki/Header_file]

%[https://en.wikipedia.org/wiki/Linguistic_relativity]

# Disclaimer

Code Smells are my [opinion](https://maximilianocontieri.com/i-wrote-more-than-90-articles-on-2021-here-is-what-i-learned).

# Credits

Photo by [K8](https://unsplash.com/@_k8_) on [Unsplash](https://unsplash.com/photos/silver-framed-eyeglasses-on-white-table-r87zX1RWECQ)
    
* * *

> Tests should be coupled to the behavior of code and decoupled from the structure of code

_Kent Beck_
 
%[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]