Outline
All .net assemblies have ‘METADATA' information stored about the type defined in
MODULES. This metadata information can be accessed by a mechanism called as
‘REFLECTION'.
Introduction
Reflection is used when you don't know at compile time which time your object is
or what action to do or on what property. REFLECTION provides several
functionalities to assembly ‘METADATA'. Through using reflection you can also
dynamically invoke methods. For invoking methods you need to add a namespace, as
given below-
System.Type.Invokemember //invoking method //
You can dynamically invoke methods, on basis of that example:
Ex
Public
Class
Ref
Private Sub Ref_Load(ByVal
sender As System.Object,
ByVal e As
System.EventArgs)
Handles MyBase.Load
Dim Pobjtype As
Type
Dim PobjObject As
Object
Dim objButtons As
New Windows.Forms.Button()
Pobjtype = PobjButtons.Get Type ()
For Each
PobjObject In Pobjtype.GetMembers
LstDisplay.Items.add(PobjObject.ToString())
Next
End Sub
End
Class
![Image-1.jpg]()
Sample source code mentioned above uses reflection to browse through ‘BUTTON'
class. If you compile and run that program, you will get output as shown in the
image display.
Applications
There are many uses for reflection. The .Net Framework uses it for
- Serialization
- Data Binding
- For Creating Tools
(It can also be used for creating tools) that
examine your code like Reflector, FxCop and NUnit as well as ORM database
frameworks. It has a wide variety of uses at runtime from logging specific
things about an object to Dependency Injection Frameworks. It can also be used
to dynamically execute methods or set properties at runtime as is done with
custom attributes. It can also be used in higher level programming such as meta
programming and self-modifying code.
Conclusion
It can also be very useful when testing your application, e.g. unit tests or
other types of test frameworks.
Ex
Create an xml file (or some other input data file in suitable format) and have
your program analyze it and call methods that are defined in the file. This is
how ‘Fitnesse work'.