Maxi Contieri

Posted on Mar 22, 2022 • Originally published at maximilianocontieri.com

Code Smell 123 - Mixed 'What' and 'How'

We love looking at the internal gears of the clock, but we need to start focusing on the hands.

TL;DR: Don't mess with implementation details. Be declarative. Not imperative.

Problems

Accidental Coupling
Coupling
Lack of design for change
Comments distinguish the 'how' and the 'what'.

Solutions

Separate 'What' and 'How' concerns.

Context

Separating concerns is very difficult in the software industry.

Functional software survives ages.

Implementative software brings coupling and is harder to change.

Choosing wise declarative names is a daily challenge.

Sample Code

Wrong

class Workflow {
    moveToNextTransition() {
        // We couple the business rule with the accidental implementation
        if (this.stepWork.hasPendingTasks) {
            throw new Exception('Preconditions are not met yet..');
        } else {
            this.moveToNextStep();
        }
    }
}

Right

class Workflow {
    moveToNextTransition() {
        if (!this.canWeMoveOn()) {
            throw new Exception('Preconditions are not met yet..');
        } else {
            this.moveToNextStep();
        }
    }

    canWeMoveOn() {
        // We hide accidental implementation 'the how'
        // under the 'what'
        return !this.stepWork.hasPendingTasks();
    }
}

Detection

[X] Manual

This is a semantic and naming smell.

Conclusion

We need to choose good names and add indirection layers when necessary.

Of course, premature optimizators will fight us, telling us we are wasting computational resources and they need to know the insights we are hiding from them.

Relations

Code Smell 92 - Isolated Subclasses Names

Maxi Contieri ・ Oct 11 '21

#poo #webdev #python #javascript

Code Smell 05 - Comment Abusers

Maxi Contieri ・ Oct 24 '20

#codenewbie #tutorial #beginners

More Info

Credits

Photo by Josh Redd on Unsplash

The idea of this smell is here:

Code Smell 118 - Return False's comment

and here

We are constantly interfacing with other people's code that might not live up to our high standards and dealing with inputs that may or may not be valid. So we are taught to code defensively. We use assertions to detect bad data and check for consistency.

Andrew Hunt

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

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