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Expression.Call Method (MethodInfo, Expression)

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

Creates a MethodCallExpression that represents a call to a static (Shared in Visual Basic) method that takes one argument.

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

Syntax

'Declaration
Public Shared Function Call ( _
    method As MethodInfo, _
    arg0 As Expression _
) As MethodCallExpression

public static MethodCallExpression Call(
    MethodInfo method,
    Expression arg0
)

Parameters

Return Value

Type: System.Linq.Expressions.MethodCallExpression
A MethodCallExpression that has the NodeType property equal to Call and the Object and Method properties set to the specified values.

Exceptions

Exception Condition
ArgumentNullException

method is null.

Examples

The following example demonstrates how to create an expression that calls a static (Shared in Visual Basic) method that takes one argument.

        ' Add the following directive to your file:
        ' Imports System.Linq.Expressions  
        Public Class SampleClass
            Shared Function Increment(ByVal arg1 As Integer) As Integer
                Return arg1 + 1
            End Function
        End Class
        Shared Sub TestCall()
            'This expression represents a call to an instance method with one argument.
            Dim callExpr As Expression = Expression.Call(
                GetType(SampleClass).GetMethod("Increment"),
                Expression.Constant(2))

            ' Print the expression.
            outputBlock.Text &= callExpr.ToString() & vbCrLf

            ' The following statement first creates an expression tree,
            ' then compiles it, and then executes it.
            outputBlock.Text &= Expression.Lambda(Of Func(Of Integer))(callExpr).Compile()() & vbCrLf
        End Sub

        ' This code example produces the following output:
        '
        ' Increment(2)
        ' 3


// Add the following directive to your file:
// using System.Linq.Expressions;  

public class SampleClass
{
   public static int Increment(int arg1)
   {
      return arg1 + 1;
   }
}

static public void TestCall(System.Windows.Controls.TextBlock outputBlock)
{

   //This expression represents a call to an instance method with one argument.
   Expression callExpr = Expression.Call(
                           typeof(SampleClass).GetMethod("Increment"),
                           Expression.Constant(2)
                       );

   // Print out the expression.
   outputBlock.Text += callExpr.ToString() + "\n";

   // The following statement first creates an expression tree,
   // then compiles it, and then executes it.
   outputBlock.Text += Expression.Lambda<Func<int>>(callExpr).Compile()() + "\n";

   // This code example produces the following output:
   //
   // Increment(2)
   // 3
}

Version Information

Silverlight

Supported in: 5, 4

Platforms

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