Expression(Of TDelegate).Compile Method

Compiles the lambda expression described by the expression tree into executable code and produces a delegate that represents the lambda expression.

Namespace:  System.Linq.Expressions
Assembly:  System.Core (in System.Core.dll)

'Declaration
Public Function Compile As TDelegate

Return Value

Type: TDelegate
A delegate of type TDelegate that represents the compiled lambda expression described by the Expression(Of TDelegate).

The Compile method produces a delegate of type TDelegate at runtime. When that delegate is executed, it has the behavior described by the semantics of the Expression(Of TDelegate).

The Compile method can be used to obtain the value of any expression tree. First, create a lambda expression that has the expression as its body by using the Lambda method. Then call Compile to obtain a delegate, and execute the delegate to obtain the value of the expression.

The following code example demonstrates how Compile is used to execute an expression tree.


        ' Lambda expression as data in the form of an expression tree. 
        Dim expression As System.Linq.Expressions.Expression(Of Func(Of Integer, Boolean)) = Function(ByVal i) i < 5
        ' Compile the expression tree into executable code. 
        Dim deleg As Func(Of Integer, Boolean) = expression.Compile()
        ' Invoke the method and print the output.
        MsgBox(String.Format("deleg(4) = {0}", deleg(4)))

        ' This code produces the following output: 
        
        ' deleg(4) = True

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8
Was this page helpful?
(1500 characters remaining)
Thank you for your feedback
Show:
© 2015 Microsoft