📘 SOLID Principles

Writing Maintainable, Scalable, and Professional Object-Oriented Code

🗝️ About This Course

This is not a beginner course.

This course is designed for developers who already have strong object-oriented programming knowledge and real coding experience.

By the time you reach this course, you already:

• Understand classes, objects, interfaces, and inheritance
• Have written real systems and projects
• Know how OOP works technically

Now comes the next level:

👉 Writing code that survives change

👉 Writing systems that scale without breaking

👉 Writing code that other developers respect

This course teaches SOLID principles, the backbone of professional software design.

SOLID is what separates:

• Junior developers from seniors
• Passing code from excellent architecture
• Code that works today from code that survives years

🔐 Why SOLID Principles Matter?

Most software problems are not syntax problems.

They are design problems.

Bad design causes:

• Rigid code
• Fragile systems
• Impossible-to-change features
• Fear of touching existing code

SOLID principles solve this.

They teach you how to:

🔹 Control change
🔹 Reduce coupling
🔹 Increase flexibility
🔹 Write testable code
🔹 Design systems that evolve safely

📌 This is why SOLID is taught in:

• Senior developer interviews
• University software engineering courses
• Professional system design discussions

🔐 What Makes This Course Different?

🔹 Assumes strong OOP background (no basics repeated)
🔹 Uses real, realistic C# examples
🔹 Shows violations first, then fixes them
🔹 Includes homeworks that force real thinking
🔹 Explains why each principle exists
🔹 Connects SOLID to Dependency Injection correctly
🔹 Designed for deep understanding, not memorization

This course teaches thinking in design, not rules.

📖 What You Will Learn?

By the end of this course, you will be able to:

🔹 Apply the Single Responsibility Principle (SRP) correctly
🔹 Design extensible systems using Open/Closed Principle (OCP)
🔹 Detect and fix violations of Liskov Substitution Principle (LSP)
🔹 Design clean, focused interfaces using ISP
🔹 Decouple systems using Dependency Inversion Principle (DIP)
🔹 Understand the difference between DIP and Dependency Injection
🔹 Refactor bad designs into clean architectures
🔹 Write code that is easier to maintain, test, and extend

🧱 How This Course Is Structured?

This course follows a professional design-learning flow:

1️⃣ Introduction to SOLID as a unified mindset
2️⃣ Each principle explained conceptually
3️⃣ Violating examples (realistic & common mistakes)
4️⃣ Correct implementations step by step
5️⃣ Homeworks that force design thinking
6️⃣ Full solutions and explanations
7️⃣ Clear summary tying everything together

Each principle includes:

🔹 Explanation
🔹 ❓ Quiz
🔹 Real C# examples
🔹 🧐 Homework
🔹 💡 Homework solution

📌 This is how architects and senior developers learn design.

🧑‍💻 Who This Course Is For?

✅ Developers with solid OOP experience
✅ Senior and mid-level developers
✅ University students aiming for high grades
✅ Students studying Software Engineering or OOP
✅ Developers preparing for technical interviews
✅ Anyone who wants to write professional-quality code

❌ Not for beginners
❌ Not for learners who just started OOP

⚠️ What This Course Is NOT?

❌ Not an introduction to OOP
❌ Not a syntax or language basics course
❌ Not a copy-paste tutorial
❌ Not about frameworks or tools

📌 This course is about design quality and thinking.

🎓 Certification & Learning Outcomes

🏅 Professional Certificate of Completion

Upon successful completion of this course, the learner will earn a

Certificate in SOLID Principles, verifying the ability to:

🔹 Apply SOLID principles correctly in real systems
🔹 Identify and fix poor object-oriented designs
🔹 Design maintainable and extensible software
🔹 Understand professional-level architecture decisions
🔹 Write code aligned with industry best practices

🔐 This certification confirms software design maturity, not beginner knowledge.

🎓 Final Outcome

After completing this course, you will not just “know SOLID”.

You will be able to:

🔹 See design problems before they happen
🔹 Refactor existing systems safely
🔹 Write code that welcomes change
🔹 Communicate design decisions professionally
🔹 Think like a senior developer

🧠 Clean design is not optional.
🧠 SOLID is the language of professional software design.

مهم جدا

للاستفادة من هذه الدورة يجب ان تكون قوي في

Object Oriented Programming 

وان تكون ممارس ومطبق لمشاريع حتى يتسنى لك الاستفادة الواقعية منها في حياتك العملية.

طلاب الجامعات بامكانهم اخذ هذه الدورة من اجل التحصيل الاكاديمي ولكن يجب اعادتها بعد ان يكون لديهم اساس قوي ليتسنى لهم

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