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API in C#: The Best Practices of Design and Implementation

Learn how to design and implement API based on the best practices developed by the .NET community.
4.4 (25 ratings)
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257 students enrolled
Created by Elias Fofanov
Last updated 10/2016
English English
$10 $35 71% off
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  • 3.5 hours on-demand video
  • 2 Articles
  • 2 Supplemental Resources
  • Full lifetime access
  • Access on mobile and TV
  • Certificate of Completion
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What Will I Learn?
Design and implement a type or an API taking care of it's users.
Encapsulate types so the other programmers would not hate you.
Code in a good style making the code clearer in its intent.
Refactor the code making it much better to read and understand.
Throw and handle exceptions properly.
Decide whether to comment a particular part of the code is a good idea or not. By the way, which comments are helpful and which are not?
Dealing with Null values
View Curriculum
  • You should already be familiar with the basics of C#.
  • You should already have some practice working with Visual Studio.

Learn how to design and implement types in C# so that the other developers won't hate you when using one of the types developed by you. It means you are going to learn how to write code of the high quality: readable, understandable and reliable.

Improve your knowledge in object-oriented programming in the context of clean coding and building types of high quality.

  • Understand the characteristics of a well-designed type
  • Grasp the principles of the convenient API development
  • Write clean code, get rid of unpleasant smells
  • Learn about what exceptions are intended for and how to throw and catch them properly
  • Protect your types from the incorrect usage making them properly encapsulated.

Foundations of building object-oriented infrastructures

Despite the fact that C# is a very rich on features language, it's very common to see poorly designed and implemented types in a real world. In fact, C# is one of the richest on features language among object-oriented languages in the world nowadays. But with great power comes great responsibility. It's challenging  to use all those features in a right way.

You probably have already heard the following well-known statement: most code sucks. Well, this course is all about how to produce code which doesn't suck.

Owning skills of producing a well-designed and well-implemented types is the prerequisite for the other developers to treat you as a real professional.

Content and Overview

This course is aimed at all the C# developers, from beginners to seniors. Topics which are covered in the course are relevant for all kinds of C# developers since all developers design and implement APIs. The topics complexity is very different. There are plenty of very simple topics, and at the same time, there are topics which require from you a solid C# background. There are plenty of code examples throughout this course, so you will learn both theoretical and practical material.

Starting with characteristics and principles of a well-designed type you will go further, learning how to give names for different members, how many parameters a method should take, is it a good idea to take a Boolean as a parameter of a method and much more than that.

Then you will learn what encapsulation really means. How to encapsulate a type? There are some trade-offs we will deal with encapsulating our types. There are many experienced programmers who don't know what encapsulation is in essence. Investigating this topic together we will see how to build a consistent and reliable type.

After mastering the topic of types encapsulating you will face the great problem of exceptions handling. Yep, it's a hard nut to crack. We will start from discussing a question of why do we use exceptions as a mechanism of errors handling. And why C# team didn't invent any other mechanisms?

In the end, we will look at how to fight with null values. As you may know, Tony Hoar said that the invention of a null value was his billion-dollar mistake.

To sum up, the course covers the following topics:

  • API development principles
  • How to give better names for API members and what naming conventions exist in the .NET platform and suited for C#.
  • Common problems encountered by C# developers in the process of designing and implementing APIs: classes vs structures, abstract classes vs interfaces, creational patterns vs constructors, how to implement dispose pattern (are you sure you understand this allegedly simple case?)
  • Common implementation smells such as poor naming, excessively long methods, output parameters and so on.
  • Common Architectural Design Smells such as Primitive Obsession, Hidden Dependencies, Violation of Law of Demeter and other.
  • How to deal with errors. It is surprisingly hard to develop robust software where errors handling is based on exceptions. We will find out why this is so and how to struggle with problems of error handling.
  • How to deal with Nulls. Null Vales have always been a pain the ass. NullReferenceException is a well-known and popular guest in our software. We will look at the possible ways of diminishing the disrupting power of null-values.
Who is the target audience?
  • This course is primarily oriented on programmers who have at least basic knowledge of C# and looking for practical guidelines concentrated on the improving of code qualities.
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Curriculum For This Course
Expand All 61 Lectures Collapse All 61 Lectures 03:17:02
Introduction to API
6 Lectures 19:32

Outline of the course "API in C#: The Best Practices of Design and Implementation".

Preview 03:20

In this lecture you'll learn what characteristics of API are important.

API's Characteristics

In this lecture you'll learn the difference between public API and private API.

Public API VS Private API

In this lecture you'll learn the main development principles of API.

API Development Principles

The conclusion for the introduction into the course "API in C#: The Best Practices of Design and Implementation".

4 Lectures 20:45

The outline of the module about naming of API members.


You'll learn abour intention-revealing names, disinformative names, easily readable names, encodings, domain names, scope and length rule and other.

General Principles of Naming

Learn about standard .NET naming conventions.

Naming Conventions in .NET

Conclusion for the module about naming API members.

Designing and Implementing Types and their Members
12 Lectures 45:06

The outline of the module where you'll learn how to design and implement types and their members in C#.


You'll learn the difference between class and structure in C#.

Preview 04:01

You'll learn the difference between an abstract class and an interface in C#.

Abstract Class VS Interface

You'll learn the caveats of abstract classes implementation in C#.

Implementing Abstract Classes

You'll learn how to choose between property and method in C#.

Property VS Method

You'll learn the caveats of constructors implementation in C#.

Implementing Constructors

You'll learn when to prefer a creational pattern over a constructor in C#.

Creational Patterns VS Constructors

You'll learn about the "Tester-Doer" pattern in C#.

Tester-Doer Pattern

You'll learn how to choose between implementing either a conversion operator or casting operator in C#.

Conversion VS Casting Operator

You'll learn about the caveats of implementing method's parameters in C#.

Implementing Parameters

You'll learn about the caveats of implementing the "Dispose" pattern in C#.

Implementing "Dispose" Pattern

The conclusion for the module where you learned how to design and implement types (API) and their members in C#.

Implementation Smells
11 Lectures 28:26

The outline of the module where you'll learn the typical implementation smells of API in C#.


You'll learn about mysterious, meaningless, shortened, ambiguous names and other naming smells.

Poor Naming

You'll learn about the violation of naming conventions. How to impose the rules of naming by harnessing the power of modern tools.

Violating Naming Conventions

You'll learn about the smell of declaring variable on top of methods.

Variable Declarations on the Top

You'll learn about the smell of magic numbers. You'll see how to refactor them.

Magic Numbers

You'll learn abou the technique "Extract Till You Drop" which was introduced by Robert Martin (aka Uncle Bob). You'll learn the pros and cons of that technique.

Too Long Method

You'll learn about the right using of ternary operators and how to avoid abusing them.

Poor Conditional Clauses

You'll learn about the smell of out-parameters and how refactor them out.

Preview 03:00

You'll learn about the smell of silly comments.


You'll learn about the smell of double negative if-statements.

Prefer Positive if-statements

The conclusion for the module where you learned the common smells of API implementation in C#.

Common Architectural Smells
7 Lectures 24:04

The outline of the module where you'll learn about common architectural smells in C#.


You'll learn about the primitives obsession, when developers inappropriately use primitive types for representing higher-level concepts.

Primitives Obsession

You'll learn about hidden dependencies by the example of inappropriate use of the Service Locator pattern.

Hidden Dependencies

You'll learn the Law of Demeter and you'll see the example of the violation of that law in C#.

Preview 06:49

You'll learn about the smell of temporal coupling and how to avoid it.

Temporal Coupling

You'll learn about the pros and cons of using switch-statements. You'll see how to refactor them into an object-oriented form.

Switch Statements

The conclusion for the module where you learned common architectural smells in C#.

Dealing with Errors
12 Lectures 36:15

The outline of the module where you'll learn about the approaches to errors handling. How to handle exceptions in C# and how to avoid them.


Learn the meaning of the "error" term. What categories of errors exist in C#.

Preview 03:31

Learn deeply what the problems accompany exceptions in C#.

Problems with Exceptions

Look at the common misconceptions concerning exceptions handling in C#.

Common Misconceptions

Learn what strategies of exceptions handling exist in C#.

Exception Handling Strategies

Learn about the Command-Query Separation principle.

CQS Principle

Learns about the interconnection between errors and functional programming.

Errors and Functional Programming

Learn what is pipelining and how to implement it via methods chaining in C#.

Pipelining by Method Chaining

A sub-conclusion about exceptions handling in C#.

Conclusion on Exceptions Handling

Learn about the built-in exception types in C#. Use them properly!

BCL Exceptions Types

Learn the rules of implementing custom exceptions types in C#.

Custom Exception Types

The conclusion for the module where you learned all nitty-gritty abour errors and exceptions handling C#.

Dealing with Nulls
9 Lectures 22:54

The outline of the module where you'll learn the approaches to dealing with nulls in C#.


You'll learn what the problems accompany null values.

Preview 02:34

Learn the Null Object pattern in C#.

Preview 02:51

Learn what is the Maybe monad and how to implement it in C#.

Maybe monad in C#

Learn how to automate null checks using the NullGuard.Fody.

Automating Null Checks

Learn how the static analysis can help to struggle with nulls.

Static Analysis

Learn about the special case (regarding null values) of returning null values.

Returning IEnumerables

The conclusion for the module where you learned the approaches to dealing with null values in C#.


Final Test
25 questions

About the Instructor
4.2 Average rating
429 Reviews
3,226 Students
4 Courses
Software Engineer

I'm thankful enough for that I love what I do.

I began my career as a postgraduate student participating in Microsoft ImagineCup contest.

I've been working with .NET platform since 2003. I've been professionally architecting and implementing software for nearly 7 years, primarily based on .NET platform. I'm passionate about building rich and powerful applications using modern technologies. I'm a certified specialist in Windows Applications and Service Communication Applications by Microsoft.

"If it's work, we try to do less. If it's art, we try to do more." - Seth Godin.

What I can say is that software is my art.

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