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Principles

Extract Method: Breaking Up Long Functions

Extract Method moves a block of a long function into its own function with a name that says what it does, until the original reads like a list of steps. Long methods hide where each job starts and ends, so changes land in the wrong place. These lessons split a grocery checkout into named steps, one extraction at a time.

Pick your language

Clean code: extract until it reads in Java, step 2: A discount in the wrong placeJava · ~4 minExtract Method in JavaClean code: extract until it reads in C#, step 2: A discount in the wrong placeC# · ~4 minExtract Method in C#Clean code: extract until it reads in Python, step 2: A discount in the wrong placePython · ~4 minExtract Method in PythonClean code: extract until it reads in PHP, step 2: A discount in the wrong placePHP · ~4 minExtract Method in PHPClean code: extract until it reads in TypeScript, step 2: A discount in the wrong placeTypeScript · ~4 minExtract Method in TypeScript

When to use it

Use it when

You have to read a whole method to find the part you need to change.

Skip it when

The lines already say what they do, and a method named after them would only repeat them.

Spot it by

Long methods, comments that label each section, and one variable that means different things as it goes.