Parameterize Method

Several methods do similar things but with different values.

“Several methods do similar things but with different internal values, numbers, or operations.”

Make it generic.

graph LR
    A[fivePercent()] -->|Refactoring| B[raises(0.05)]
    C[tenPercent()] -->  B

When to apply (Smells)

• Duplication: raise5Percent(), raise10Percent().

Motivation

• DRY: One method to rule them all.

Mechanics (Steps)

1. Create a parameterized method.
2. Replace specific methods with calls to the parameterized one.
3. Delete specific methods.

Explanation

Problem

fivePercent(), tenPercent().

Solution

percent(arg).

Pros and Cons

Pros	Cons
Less duplication	None

Code example

Typescript

Before

After

PHP

Before

After