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Call Method (Expression, MethodInfo)

Expression.Call Method (Expression, MethodInfo)

Creates a MethodCallExpression that represents a call to a method that takes no arguments.

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

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

Parameters

instance
Type: System.Linq.Expressions.Expression

An Expression that specifies the instance for an instance method call (pass Nothing 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.

ExceptionCondition
ArgumentNullException

method is Nothing.

-or-

instance is Nothing and method represents an instance method.

ArgumentException

instance.Type is not assignable to the declaring type of the method represented by method.

To represent a call to a static (Shared in Visual Basic) method, pass in Nothing for the instance parameter when you call this method.

If method represents an instance method, the Type property of instance must be assignable to the declaring type of the method represented by method.

The Arguments property of the resulting MethodCallExpression is empty. The Type property is equal to the return type of the method represented by method.

The following code example shows how to create an expression that calls a method without arguments.

        ' 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.
        Console.WriteLine(callExpr.ToString())

        ' The following statement first creates an expression tree, 
        ' then compiles it, and then executes it.  
        Console.WriteLine(Expression.Lambda(Of Func(Of String))(callExpr).Compile()())

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

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8

Portable Class Library

Supported in: Portable Class Library
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