Code Smell 103 - Double Encapsulation

Calling our own accessor methods might seem a good encapsulation idea. But it is not.

TL;DR: Don't use setters and getters, even for private use

Problems

Setters
Getters
Exposing private attributes

Solutions

Remove setters
Remove getters
Protect your attributes

Context

Using double encapsulation was a standard procedure in the 90s.

We wanted to hide implementation details even for private use.

This was hiding another smell when too many functions relies on data structure and accidental implementation.

For example, we can change an object internal representation and rely on its external protocol.

Cost/benefit is not worth it.

Sample Code

Wrong

contract MessageContract {
    string message = "Let's trade";

    function getMessage() public constant returns(string) {
        return message;
    }

    function setMessage(string newMessage) public {
        message = newMessage;
    }

    function sendMessage() public constant {
        this.send(this.getMessage());
        //We can access property but make a self call instead
    }
}

Right

contract MessageContract {
    string message = "Let's trade";

    function sendMessage() public constant {
        this.send(message);
    }
}

Detection

[X] Semiautomatic

We can infer getters and setters and check if they are invoked from the same object.

Conclusion

Double encapsulation was a trendy idea to protect accidental implementation, but it exposed more than protected.

Relations

Code Smell 37 - Protected Attributes

Maxi Contieri ・ Nov 29 '20

#oop #webdev #tutorial #codenewbie

Code Smell 28 - Setters

Maxi Contieri ・ Nov 19 '20

#oop #codenewbie #programming #webdev

Code Smell 68 - Getters

Maxi Contieri ・ Apr 29 '21

#codenewbie #tutorial #oop #programming

More Info

Credits

Photo by Ray Hennessy on Unsplash

Encapsulate the concept that varies.

Erich Gamma

Software Engineering Great Quotes

Maxi Contieri ・ Dec 28 '20

#codenewbie #programming #quotes #software

This article is part of the CodeSmell Series.

How to Find the Stinky parts of your Code

Maxi Contieri ・ May 21 '21

#codenewbie #tutorial #codequality #beginners