Expression.Call Method (Expression, MethodInfo)

Parameters

• instance
  Type: System.Linq.Expressions.Expression
  An Expression that specifies the instance for an instance method call (pass nulla null reference (Nothing in Visual Basic) for a static (Shared in Visual Basic) method).

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

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   

        ' This expression represents a call to an instance method without arguments.
        Dim callExpr As Expression = Expression.Call(
            Expression.Constant("sample string"), GetType(String).GetMethod("ToUpper", New Type() {}))

        ' 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 String))(callExpr).Compile()() & vbCrLf

        ' This code example produces the following output:
        '
        ' "sample string".ToUpper
        ' SAMPLE STRING

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

       // This expression represents a call to an instance method without arguments.
       Expression callExpr = Expression.Call(
           Expression.Constant("sample string"), typeof(String).GetMethod("ToUpper", new Type[] { }));

       // 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<String>>(callExpr).Compile()() + "\n";

       // This code example produces the following output:
       //
       // "sample string".ToUpper
       // SAMPLE STRING