Programmers use Null as different flags. It can hint at an absence, an undefined value, en error etc. Multiple semantics lead to coupling and defects. Programmers use Null as different flags. It can hint at an absence, an undefined value, en error etc. Multiple semantics lead to coupling and defects. TL;DR: Null is schizophrenic and does not exist in real-world. Its creator regretted and programmers around the world suffer from it. Don't be a part of it. TL;DR: Null is schizophrenic and does not exist in real-world. Its creator regretted and programmers around the world suffer from it. Don't be a part of it. Problems 😔 Coupling between callers and senders.
If/Switch/Case Polluting.
Null is not polymorphic with real objects. Hence, Null Pointer Exception
Null does not exist on real-world. Thus, it violates Bijection Principle Coupling between callers and senders. If/Switch/Case Polluting. If Switch Null is not polymorphic with real objects. Hence, Null Pointer Exception Null Pointer Exception Null does not exist on real-world. Thus, it violates Bijection Principle Bijection Principle Solutions 😃 Avoid Null.
Use the NullObject pattern to avoid ifs.
Use Optionals. Avoid Null. Use the NullObject pattern to avoid ifs. NullObject pattern Use Optionals. Optionals https://hackernoon.com/null-the-billion-dollar-mistake-8t5z32d6?embedable=true https://hackernoon.com/null-the-billion-dollar-mistake-8t5z32d6?embedable=true Refactorings ⚙️ https://hackernoon.com/code-refactoring-tips-no-015-remove-null?embedable=true https://hackernoon.com/code-refactoring-tips-no-015-remove-null?embedable=true https://hackernoon.com/refactoring-029-how-to-replace-null-with-collection?embedable=true https://hackernoon.com/refactoring-029-how-to-replace-null-with-collection?embedable=true https://hackernoon.com/refactoring-014-how-to-remove-if?embedable=true https://hackernoon.com/refactoring-014-how-to-remove-if?embedable=true Context 💬 When you use null, you encode multiple meanings into a single value. Sometimes you want to represent an absence. Sometimes you mean you have not loaded your objects yet. Sometimes you mean error. Callers must guess your intent and add conditionals to protect themselves. You spread knowledge about internal states across your codebase. Sample Code 📖 Wrong 🚫 class CartItem {
    constructor(price) {
        this.price = price;
    }
}

class DiscountCoupon {
    constructor(rate) {
        this.rate = rate;
    }
}

class Cart {
    constructor(selecteditems, discountCoupon) {
        this.items = selecteditems;
        this.discountCoupon = discountCoupon;
    }

    subtotal() {
        return this.items.reduce((previous, current) => 
            previous + current.price, 0);
    }

    total() {
        if (this.discountCoupon == null)
            return this.subtotal();
        else
            return this.subtotal() * (1 - this.discountCoupon.rate);
    }
}

cart = new Cart([
    new CartItem(1),
    new CartItem(2),
    new CartItem(7)
    ], new DiscountCoupon(0.15)]);
// 10 - 1.5 = 8.5

cart = new Cart([
    new CartItem(1),
    new CartItem(2),
    new CartItem(7)
    ], null);
// 10 - null  = 10 class CartItem {
    constructor(price) {
        this.price = price;
    }
}

class DiscountCoupon {
    constructor(rate) {
        this.rate = rate;
    }
}

class Cart {
    constructor(selecteditems, discountCoupon) {
        this.items = selecteditems;
        this.discountCoupon = discountCoupon;
    }

    subtotal() {
        return this.items.reduce((previous, current) => 
            previous + current.price, 0);
    }

    total() {
        if (this.discountCoupon == null)
            return this.subtotal();
        else
            return this.subtotal() * (1 - this.discountCoupon.rate);
    }
}

cart = new Cart([
    new CartItem(1),
    new CartItem(2),
    new CartItem(7)
    ], new DiscountCoupon(0.15)]);
// 10 - 1.5 = 8.5

cart = new Cart([
    new CartItem(1),
    new CartItem(2),
    new CartItem(7)
    ], null);
// 10 - null  = 10 Right 👉 class CartItem {
    constructor(price) {
        this.price = price;
    }
}

class DiscountCoupon {
    constructor(rate) {
        this.rate = rate;
    }

    discount(subtotal) {
        return subtotal * (1 - this.rate);
    }
}

class NullCoupon {
    discount(subtotal) {
        return subtotal;
    }
}

class Cart {
    constructor(selecteditems, discountCoupon) {
        this.items = selecteditems;
        this.discountCoupon = discountCoupon;
    }

    subtotal() {
        return this.items.reduce(
            (previous, current) => previous + current.price, 0);
    }

    total() {
        return this.discountCoupon.discount(this.subtotal());
    }
}

cart = new Cart([
    new CartItem(1),
    new CartItem(2),
    new CartItem(7)
    ], new DiscountCoupon(0.15));
// 10 - 1.5 = 8.5

cart = new Cart([
    new CartItem(1),
    new CartItem(2),
    new CartItem(7)
    ], new NullCoupon());
// 10 - nullObject = 10 class CartItem {
    constructor(price) {
        this.price = price;
    }
}

class DiscountCoupon {
    constructor(rate) {
        this.rate = rate;
    }

    discount(subtotal) {
        return subtotal * (1 - this.rate);
    }
}

class NullCoupon {
    discount(subtotal) {
        return subtotal;
    }
}

class Cart {
    constructor(selecteditems, discountCoupon) {
        this.items = selecteditems;
        this.discountCoupon = discountCoupon;
    }

    subtotal() {
        return this.items.reduce(
            (previous, current) => previous + current.price, 0);
    }

    total() {
        return this.discountCoupon.discount(this.subtotal());
    }
}

cart = new Cart([
    new CartItem(1),
    new CartItem(2),
    new CartItem(7)
    ], new DiscountCoupon(0.15));
// 10 - 1.5 = 8.5

cart = new Cart([
    new CartItem(1),
    new CartItem(2),
    new CartItem(7)
    ], new NullCoupon());
// 10 - nullObject = 10 Detection 🔍 Most Linters can flag null usages and warn you. Exceptions 🛑 You sometimes need to deal with null when you integrate with databases, legacy APIs, or external protocols. You must contain null at the boundaries and convert it immediately into meaningful objects. Tags 🏷️ Null Null Level 🔋 [x] Intermediate Why the Bijection Is Important 🗺️ When you use null, you break the bijection between your code and the MAPPER. bijection MAPPER Nothing in the mapper behaves like null. Absence, emptiness, and failure mean different things. When you collapse them into null, you force your program to guess reality and you invite defects. AI Generation 🤖 AI generators often introduce this smell. They default to null when they lack context or want to keep examples short and also because it is widespread (but harmful) industry default. AI Detection 🧲 You can instruct AI to remove nulls with simple rules. When you ask for explicit domain objects and forbid nullable returns, generators usually fix the smell correctly. Try Them! 🛠 Remember: AI Assistants make lots of mistakes Remember: AI Assistants make lots of mistakes Suggested Prompt: Rewrite this code to remove all null returns. Model absence explicitly using domain objects or collections. Do not add conditionals Suggested Prompt: Rewrite this code to remove all null returns. Model absence explicitly using domain objects or collections. Do not add conditionals Without Proper Instructions 📵 ChatGPT
Claude
Perplexity
Copilot
You
Gemini
DeepSeek
Meta AI
Grok
Qwen ChatGPT ChatGPT Claude Claude Perplexity Perplexity Copilot Copilot You You Gemini Gemini DeepSeek DeepSeek Meta AI Meta AI Grok Grok Qwen Qwen With Specific Instructions 👩‍🏫 ChatGPT
Claude
Perplexity
Copilot
You
Gemini
DeepSeek
Meta AI
Grok
Qwen ChatGPT ChatGPT Claude Claude Perplexity Perplexity Copilot Copilot You You Gemini Gemini DeepSeek DeepSeek Meta AI Meta AI Grok Grok Qwen Qwen Conclusion 🏁 Null is the billion-dollar mistake. Yet, most program languages support them and libraries suggest its usage. Null is the billion-dollar mistake. Yet, most program languages support them and libraries suggest its usage. Relations 👩‍❤️‍💋‍👨 https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xviii https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xviii https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xxxii https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xxxii https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xix https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xix https://hackernoon.com/how-to-get-rid-of-annoying-ifs-forever-zuh3zlo https://hackernoon.com/how-to-get-rid-of-annoying-ifs-forever-zuh3zlo https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-viii-8mn3352 https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-viii-8mn3352 https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xxx https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xxx https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xliii https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xliii https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xxxix https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xxxix https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xxvi https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xxvi https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xlii https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xlii https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xxxii https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xxxii https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xx-we-have-reached-100 https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xx-we-have-reached-100 https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-ix-7rr33ol https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-ix-7rr33ol https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-v-evj3zs9 https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-v-evj3zs9 More Information 📕 https://hackernoon.com/null-the-billion-dollar-mistake-8t5z32d6?embedable=true https://hackernoon.com/null-the-billion-dollar-mistake-8t5z32d6?embedable=true Credits 🙏 Photo by Kurt Cotoaga on Unsplash Kurt Cotoaga Unsplash I couldn't resist the temptation to put in a null reference, simply because it was so easy to implement. This has led to innumerable errors, vulnerabilities, and system crashes, which have probably caused a billion dollars of pain and damage in the last forty years. I couldn't resist the temptation to put in a null reference, simply because it was so easy to implement. This has led to innumerable errors, vulnerabilities, and system crashes, which have probably caused a billion dollars of pain and damage in the last forty years. Tony Hoare Tony Hoare https://hackernoon.com/400-thought-provoking-software-engineering-quotes?embedable=true https://hackernoon.com/400-thought-provoking-software-engineering-quotes?embedable=true This article is part of the CodeSmell Series. https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-i-xqz3evd?embedable=true https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-i-xqz3evd?embedable=true

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