Long Method

Also Known As

TL;DR

Explanation

Long methods are one of the most common code smells. A method doing many things is hard to name accurately, hard to test in isolation, and hard to reuse. As a rough guide: if you cannot see the entire method without scrolling, it's worth examining. The refactoring is Extract Method — identify a coherent block of lines that does one thing, give it a descriptive name, and move it to a private helper. Good method names make the original method read like a table of contents.

Common Misconception

Why It Matters

Common Mistakes

• Adding logic inline instead of extracting a named method — 'it's only a few lines' compounds over time.
• Methods that handle multiple abstraction levels: high-level orchestration mixed with low-level detail.
• Not using early return to reduce nesting — deep nesting is a long-method symptom.
• Test methods that are as long as the code they test — long tests indicate long production code.

Code Examples

public function checkout(Cart $cart): Receipt {
    // validate items (20 lines)
    // calculate discounts (15 lines)
    // charge card (10 lines)
    // send email (15 lines)
    // update inventory (10 lines)
    // log audit (5 lines)
    // 75 lines total
}

public function checkout(Cart $cart): Receipt {
    $this->validateItems($cart);
    $total   = $this->calculateTotal($cart);
    $charge  = $this->chargeCard($cart->customer, $total);
    $receipt = Receipt::create($charge);
    $this->mailer->sendReceipt($receipt);
    $this->inventory->deduct($cart);
    $this->audit->log('checkout', $receipt);
    return $receipt;
}

References

• ↗ https://refactoring.guru/smells/long-method

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