Expression.ElementInit Method (MethodInfo, IEnumerable(Of Expression))


Creates an ElementInit, given an IEnumerable(Of T) as the second argument.

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

Public Shared Function ElementInit (
	addMethod As MethodInfo,
	arguments As IEnumerable(Of Expression)
) As ElementInit


Type: System.Reflection.MethodInfo

A MethodInfo to set the AddMethod property equal to.

Type: System.Collections.Generic.IEnumerable(Of Expression)

An IEnumerable(Of T) that contains Expression objects to set the Arguments property equal to.

Return Value

Type: System.Linq.Expressions.ElementInit

An ElementInit that has the AddMethod and Arguments properties set to the specified values.

Exception Condition

addMethod or arguments is null.


The method that addMethod represents is not named "Add" (case insensitive).


The method that addMethod represents is not an instance method.


arguments does not contain the same number of elements as the number of parameters for the method that addMethod represents.


The Type property of one or more elements of arguments is not assignable to the type of the corresponding parameter of the method that addMethod represents.

The addMethod parameter must represent an instance method named "Add" (case insensitive). The add method must have the same number of parameters as the number of elements in arguments. The Type property of each element in arguments must be assignable to the type of the corresponding parameter of the add method, possibly after quoting.


An element will be quoted only if the corresponding method parameter is of type Expression. Quoting means the element is wrapped in a Quote node. The resulting node is a UnaryExpression whose Operand property is the element of arguments.

The following example demonstrates how to use the ElementInit(MethodInfo, Expression()) method to create an ElementInit that represents calling the Add method to initialize an element of a dictionary collection.

Dim tree As String = "maple"

Dim addMethod As System.Reflection.MethodInfo = _
    Type.GetType("System.Collections.Generic.Dictionary`2[System.Int32, System.String]").GetMethod("Add")

' Create an ElementInit that represents calling
' Dictionary(Of Integer, String).Add(tree.Length, tree).
Dim elementInit As System.Linq.Expressions.ElementInit = _
    System.Linq.Expressions.Expression.ElementInit( _
        addMethod, _
        System.Linq.Expressions.Expression.Constant(tree.Length), _


' This code produces the following output:
' Void Add(Int32, System.String)(5,"maple")

Universal Windows Platform
Available since 8
.NET Framework
Available since 3.5
Portable Class Library
Supported in: portable .NET platforms
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
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