Expression.Call Method (MethodInfo, Expression, Expression)

Parameters

• method
  Type: System.Reflection.MethodInfo
  A MethodInfo to set the Method property equal to.

• arg0
  Type: System.Linq.Expressions.Expression
  The Expression that represents the first argument.

• arg1
  Type: System.Linq.Expressions.Expression
  The Expression that represents the second argument.

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.

' 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
}