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Expression.Call Method (MethodInfo, Expression, Expression)

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

Creates a MethodCallExpression that represents a call to an static method that takes two arguments.

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

Syntax

'Declaration
Public Shared Function Call ( _
    method As MethodInfo, _
    arg0 As Expression, _
    arg1 As Expression _
) As MethodCallExpression

public static MethodCallExpression Call(
    MethodInfo method,
    Expression arg0,
    Expression arg1
)

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 code example shows how to create an expression that calls an instance method that has two arguments.

' Add the following directive to your file:
' Imports System.Linq.Expressions  
Public Class SampleClass
    Public Function AddIntegers(ByVal arg1 As Integer, ByVal arg2 As Integer) As Integer
        Return (arg1 + arg2)
    End Function
End Class
Public Shared Sub TestCall()
    ' This expression represents a call to an instance method that has two arguments.
    ' The first argument is an expression that creates a new object of the specified type.
    Dim callExpr As Expression = Expression.Call(
        Expression.[New](GetType(SampleClass)),
        GetType(SampleClass).GetMethod("AddIntegers", New Type() {GetType(Integer), GetType(Integer)}),
        Expression.Constant(1),
        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:
'
' new SampleClass().AddIntegers(1, 2)
' 3

// Add the following directive to your file:
// using System.Linq.Expressions;  
public class SampleClass
{
   public int AddIntegers(int arg1, int arg2)
   {
      return arg1 + arg2;
   }
}

static public void TestCall(System.Windows.Controls.TextBlock outputBlock)
{
   // This expression represents a call to an instance method that has two arguments.
   // The first argument is an expression that creates a new object of the specified type.
   Expression callExpr = Expression.Call(
       Expression.New(typeof(SampleClass)),
       typeof(SampleClass).GetMethod("AddIntegers", new Type[] { typeof(int), typeof(int) }),
       Expression.Constant(1),
       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:
   //
   // new SampleClass().AddIntegers(1, 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.