Статья
11/18/2011

Expression<TDelegate>.Compile Method

Microsoft Silverlight will reach end of support after October 2021. Learn more.

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)

Syntax

'Declaration
Public Function Compile As TDelegate

public TDelegate Compile()

Return Value

Type: TDelegate
A delegate of type TDelegate that represents the compiled lambda expression described by the Expression<TDelegate>.

Remarks

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<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.

Platform Notes

Silverlight for Windows Phone

The Compile method is not supported in Silverlight for Windows Phone.

Examples

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(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.
      outputBlock.Text &= String.Format("deleg(4) = {0}", deleg(4)) & vbCrLf

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


      // Lambda expression as data in the form of an expression tree.
      System.Linq.Expressions.Expression<Func<int, bool>> expr = i => i < 5;
      // Compile the expression tree into executable code.
      Func<int, bool> deleg = expr.Compile();
      // Invoke the method and print the output.
      outputBlock.Text += String.Format("deleg(4) = {0}", deleg(4)) + "\n";

      /*  This code produces the following output:

          deleg(4) = True
      */

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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