Slides are based on "Effective C#. 2nd edition. Bill Wagner" book.

1. EFFECTIVE C# PART1
yuriyseniuk.blogspot.com Yuriy Seniuk

2. Part1. Agenda
 Item 1: Use Properties Instead of
Accessible Data Members
 Item 2: Prefer readonly to const
 Item 3: Prefer the is or as Operators to
Casts
 Item 4: Use Conditional Attributes Instead
of #if
 Item 5: Always Provide ToString()

3. 1. Properties
 Properties have the same performance as
fields;
 Properties can be bound, Fields – not;
 Properties are useful during thread
synchronization;
 Properties can be virtual;
 Properties can be used in interfaces;
 Properties can have different access levels;
 Property syntax used to create indexers;
 Indexers can be multidimensional;

4. 1. Properties
 Indexers can use non integer parameters;
 Class can contains several indexers;
 Fields can not be substituted by properties due
it’s binary incompatibility.

5. 2. Prefer readonly to const
 Readonly – runtime constants;
 Const – compile time constants;
 --------------------------------------
 Compile time constants is slightly faster;
 Const can be used only with value types;
 Const must be used when in future releases it
never be changed.

6. 3. Prefer is/as operator to Cast
 is/as does not perform any user conversions;
 as can be applied only to reference types;
 is can be used for verification of types
capabilities;
 foreach uses non generic IEnumerable
interface and cast;
 .Cast<T>();
 .OfType<T>();
 Microsoft asks to avoid user defined casts;

7. 4. Use Conditional Attr insted of
#if
 #if/#endif used to produce different builds;
 Using Conditional attr you fully isolates your code;
Log() --- this method creates empty code invocation.
{
#if DEBUG
//some code
#endif
}
[Conditional(“DEBUG”)]
Log()
{
//some code
}

8. 4. Use Conditional Attr insted of
#if
 Conditional attributes can be combined:
[Conditional(“DEBUG”), Conditional(“TRACE”)]
 It is possible to combine attributes on old way:
#if(DEBUG && TRACE)
#define BOTH
#endif
 Conditional attributes can be used in methods
that returns void;

9. 4. Use Conditional Attr insted of
#if
 Do not use parameters in conditional methods
[Conditional(“DEBUG”)]
log(string mess)
{
}
to avoid this one
string mess = string.Empty;
log(mess = GetMessage()); //method will never be executed in DEBUG build.
Console.WriteLine(mess);

10. 5. Always provide ToString()
 Override ToString() to create a reasonable
human-readable class representation;
 In anonymous types ToString() displays the
value of each property;
 Use IFormatable for complicated types;
 Support “G”, String.Empty and null in
IFormatable;
 Use IFormatProvider to enhance closed
libraries.
 IFormatProvider can be used with types that is
not inherited from IFormatable