TL;DR: Don't make generalizations beyond real knowledge.

Problems

• Overgeneralization

• Bijection violation

Solutions

1. Think before making structural generalizations

Context

Refactoring is not just looking at structural code.

We need to refactor behavior and check if it needs an abstraction.

Sample Code

Wrong

fn validate_size(value: i32) {
         validate_integer(value);
}

fn validate_years(value: i32) {
         validate_integer(value);
}

fn validate_integer(value: i32) {
         validate_type(value, :integer);
         validate_min_integer(value, 0);
}

Right

fn validate_size(value: i32) {
        validate_type(value, Type::Integer);
        validate_min_integer(value, 0);
}

fn validate_years(value: i32) {
        validate_type(value, Type::Integer);
        validate_min_integer(value, 0);
}

// Duplication is accidental, therefore we should not abstract it

Detection

[X] Manual

This is a semantic smell.

Tags

• Duplication

Conclusion

Software development is a thinking activity.

We have automated tools to help and assist us. We need to be in charge.

Relations

More Info

• DRY—The Evils of Duplication

Disclaimer

Code Smells are just my opinion.

Credits

Photo by Matthew Henry on Unsplash

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Duplication is far cheaper than the wrong abstraction.

Sandi Metz

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This article is part of the CodeSmell Series.