This is an introductory presentation on the topic of C# Reflection.

1. Smoke and Mirrors
- Reflection in C#
Wekoslav
Stefanovski

2. What is reflection
Definition - to look back to itself
• Fields Run Time Type Information
• Methods Discovering class information
solely at run time
• Properties
.net Reflection
Assembly Access based on
metadata

3. System.Type
• Base of all reflection classes and properties -
primary way to access metadata
– Represents all kinds of types (class, interface,
enumeration…)
• GetType() is a Method of System.Object
• typeof() operator returns Type object
• A Type is unique per type
• Only one instance of Type per type per
application domain

4. MemberInfo class
• Provides access to member metadata.
• MemberType propery is useful to
determine the tipe of a member
• Ancestor to all other XXXInfo classes
• Actually an ancestor to Type

5. Other XXXInfo Classes
• PropertyInfo
– GetGetMethod; GetSetMethod
• FieldInfo
– GetValue; SetValue
• MethodInfo
– Invoke
• ConstructorInfo
• EventInfo

6. Attributes
• An information which marks the
elements of code.
• A class that derives from
System.Attribute
• Multiple points of consumption –
compiler, CLR, debugger, user code
• Can use both positional and named
parameters

7. Using Custom Attributes
• Type.GetCustomAttributes
• Attribute.GetCustomAttribute
• Only way to get information about
attributes applied to an object in user
code

8. System.Activator
• A generalized way for creating objects
at runtime
• CreateInstance method – generic and
regular
• Other Uses

9. Reflection and Generics
• Difference between regular types,
generic types, and specialized types
• Type.IsGenericType
• Type.IsGenericTypeDefinition
• Type.MakeGenericType
• MethodInfo.IsGenericMethod
• MethodInfo.IsGenericMethodDefinition

10. Reflection.Emit
• Creating, modifying and running of
code in runtime
• Does not use C#, uses MSIL
• Very complex, very powerfull

11. Speed of Reflecting
• As expected, direct access is much
faster than reflection
• Performance hit – anywhere from 5 to
150 times slower
• Avoid using lots of reflection in tight
loops
• We should weight if the usefulness in
the scenario justifies the slowdown.

12. References
• Generics Terminology in .NET Framework -
http://blogs.msdn.com/parthopdas/archive/2005/10/21/483463.aspx
• Hello World.Emit -
http://blogs.msdn.com/joelpob/archive/2004/01/21/61411.aspx
• Programming C#: Attributes and Reflection -
http://www.ondotnet.com/pub/a/dotnet/excerpt/prog_csharp_ch18/index.html
?page=1
• How Microsoft Uses Reflection - http://msdn2.microsoft.com/en-
us/magazine/cc163960.aspx
• Real-world Reflection in .NET -
http://www.devx.com/dotnet/Article/31578/1954
• Reflection - Dodge Common Performance Pitfalls
http://msdn2.microsoft.com/en-us/magazine/cc163759.aspx
• .NET Reflection: Dynamically Bind Your Data Layer
-http://msdn.microsoft.com/msdnmag/issues/02/08/NETReflection/default.as
px
• And many others

13. Questions?