My notes on "Clean Code" by Robert C. Martin

These are my notes on the book "Clean Code" by Robert C. Martin from Prentice Hall.

I am in agreement with almost everything that this book says; the following notes are either quotes from the book which I found especially interesting and/or especially well written, or they point out issues that I disagree with, or errata which objectively need correction. If some point from the book is not mentioned below, then I agree with it.

C# Blooper №14: Weird / annoying interface method visibility rules.

Before reading any further, please read the disclaimer.

As it turns out, an explicit interface method implementation in C# must be tied to the base-most interface to which it belongs; it cannot be tied to a descendant interface.

namespace Test14
{
    class Test
    {
        interface A
        {
            void F();
        }

        interface B: A
        {
        }

        class C: B
        {
            void A.F() //OK
            {
            }

            void B.F() //error CS0539: 'B.F' in explicit interface declaration is not a member of interface
            {
            }
        }
    }
}

Well, sorry, but... it is.

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C# Blooper №13: Stack and Queue do not implement ICollection

Before reading any further, please read the disclaimer.

This is a blooper of the Common Language Runtime (CLR), not of the language itself: Stack<T> and Queue<T> derive from ICollection, but not from ICollection<T>, so they do not support the Remove( T ) method! Why, oh why?

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C# Blooper №12: 'Where' constraints not included in method signatures

Before reading any further, please read the disclaimer.

When writing generic methods in C#, it is possible to use the 'where' keyword to specify constraints to the types that the generic parameters can take. Unfortunately, these constraints cannot be used for resolving overloaded methods. Case in point:

namespace Test12
{
    class Test
    {
        public static bool Equals<T>( T a, T b ) where T: class
        {
            return object.Equals( a, b );
        }

        public static bool Equals<T>( T a, T b ) where T: struct //error CS0111: Type 'Test' already defines a member called 'Equals' with the same parameter types
        {
            return a.Equals( b );
        }
    }
}

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C# Blooper №11: Zero to Enum conversion weirdness

Before reading any further, please read the disclaimer.

When you assign an enum to int, you have to cast it. That's good. When you assign an int to enum, you also have to cast it. That's also good. But if you assign zero to an enum, you don't have to cast it! Go figure.

namespace Test11
{
    class Test
    {
        public enum myenum
        {
            a, b, c
        }

        void test_myenum( myenum f, int i )
        {
            i = (int)myenum.a; //need to cast; that's good.
            f = (myenum)5; //need to cast; that's still good.
            f = 0; //wtf? no need to cast?
        }
    }
}

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C# Blooper №10: Switch statements are not properly formatted.

Before reading any further, please read the disclaimer.

This is rather a Microsoft Visual Studio blooper than a Microsoft C# blooper: When formatting source code, Visual Studio offers an "indent case contents" option, but you will only find it useful if you happen to have a crooked notion as to how switch statements should be formatted. The one and only normal form of formatting switch statements is not supported.

namespace Test10
{
    class Test
    {
        void statement() { }

        void test( int a )
        {
            /* with "indent case contents" option selected: */
            switch( a )
            {
                case 42:
                    /* this is not properly indented */
                    {
                        statement();
                        break;
                    }
                default:
                    /* this is properly indented */
                    statement();
                    break;
            }

            /* with "indent case contents" option deselected: */
            switch( a )
            {
                case 42:
                /* this is properly indented */
                {
                    statement();
                    break;
                }
                default:
                /* this is not properly indented */
                statement();
                break;
            }

            /* the normal way of indenting cannot be achieved: */
            switch( a )
            {
                case 42:
                {
                    statement();
                    break;
                }
                default:
                    statement();
                    break;
            }
        }
    }
}

I know, you might disagree that my way of formatting switch statements is in any way 'normal'. So, in your case, let us agree on this: my way of formatting switch statements, whether you like it or not, is in perfect accordance to the way I format the rest of my code; and since Visual Studio allows me to precisely describe my coding style, it should also allow for a switch statement style that matches the rest of my code.

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C# Blooper №9: Annoying case statement fall-through rules.

Before reading any further, please read the disclaimer.

Overall, C# takes an approach which is far more friendly to novice programmers than its predecessors, C and C++ were. For example, in the case of switch statements, C# does not allow the old, error-prone style of C and C++ where you could simply fall through from one case statement to the following one; instead, at the end of each case statement C# requires either a break statement, or a goto statement to explicitly jump to another label. That's all very nice and dandy, except for one thing: C# requires a break or goto even at the last case statement of a switch statement!

namespace Test9
{
    class Test
    {
        void statement() { }

        void wtf_is_it_with_falling_through_the_last_case_label( int a )
        {
            switch( a )
            {
                case 42:
                    statement();
                    break;
                default:
                    statement();
                    break; //Need this 'break' or else: CS0163: Control cannot fall through from one case label ('default:') to another
            }
        }
    }
}

I mean, seriously, WTF?

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C# Blooper №8: No warnings for conditions that are always true/false

Before reading any further, please read the disclaimer.

The Microsoft C# compiler does not issue 'condition is always true' and 'condition is always false' warnings. Perhaps these warnings are not particularly meaningful in Java, which lacks conditional compilation directives, and therefore if( true ) and if( false ) are the only means of achieving conditional compilation; but in C#, which has special conditional compilation directives, conditions which are always true or always false are invariably so by mistake; therefore, these warnings would indeed be meaningful, and useful.

namespace Test8
{
    class Test
    {
        void statement() { }

        void test()
        {
            if( true ) //no warning about 'condition is always true'.
                statement();

            while( false ) //no warning about 'condition is always false', even though the compiler obviously knows what's going on, since the following warning is issued:
                statement(); //warning CS0162: Unreachable code detected 
        }
    } 
}

For more information see Why the Microsoft C# compiler lacks many useful warnings.

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C# Blooper №7: No warnings about unused private methods.

Before reading any further, please read the disclaimer.

If you have a private method which is never used, you will not be given a warning about it by the Microsoft C# compiler. This means that your app will likely get shipped with unnecessary chunks of code in it, some of them possibly containing string litterals that were never meant to make it out of the development environment, or even requiring libraries to be linked which were never meant to be required on the field.

namespace Test7
{
    class Test
    {
        private void unused() //no warning about unused private method.
        {
        }
    }
}

For more information see Why the Microsoft C# compiler lacks many useful warnings.

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C# Blooper №6: No warnings about unused parameters.

Before reading any further, please read the disclaimer.

One common mistake that programmers make is to forget to make use of a parameter to a method. This can lead to quite subtle bugs that are hard to track down and correct.

Now, other language compilers are kind enough to warn the programmer that a parameter is unused, and they also allow temporary suppression of the warning for the rare case when such lack of use is legitimate. But not so in Visual C#. If you forget to use a parameter in Visual C#, you will not know unless you run the "Code Analysis" tool on it.

namespace Test6
{
    class Test
    {
        void moo( int a ) //no warning about unused parameter 'a'.
        {
        }
    }
}

For more information see Why the Microsoft C# compiler lacks many useful warnings.

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