ConstructorInfo Class

[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]

Discovers the attributes of a class constructor and provides access to constructor metadata.

Inheritance Hierarchy

System..::.Object
System.Reflection..::.MemberInfo
System.Reflection..::.MethodBase
System.Reflection..::.ConstructorInfo

Namespace: System.Reflection
Assembly: mscorlib (in mscorlib.dll)

Syntax

Public MustInherit Class ConstructorInfo _
    Inherits MethodBase
public abstract class ConstructorInfo : MethodBase

The ConstructorInfo type exposes the following members.

Properties

Name Description
Attributes Gets the attributes associated with this method. (Inherited from MethodBase.)
CallingConvention Gets a value that indicates the calling conventions for this method. (Inherited from MethodBase.)
ContainsGenericParameters Gets a value that indicates whether the generic method contains unassigned generic type parameters. (Inherited from MethodBase.)
CustomAttributes Gets a collection that contains this member's custom attributes. (Inherited from MemberInfo.)
DeclaringType Gets the class that declares this member. (Inherited from MemberInfo.)
IsAbstract Gets a value that indicates whether the method is abstract (MustInherit in Visual Basic). (Inherited from MethodBase.)
IsAssembly Gets a value that indicates whether the potential visibility of this method or constructor is described by MethodAttributes..::.Assembly; that is, the method or constructor is visible at most to other types in the same assembly, and is not visible to derived types outside the assembly. (Inherited from MethodBase.)
IsConstructor Gets a value that indicates whether the method is a constructor. (Inherited from MethodBase.)
IsFamily Gets a value that indicates whether the visibility of this method or constructor is described by MethodAttributes..::.Family; that is, the method or constructor is visible only within its class and derived classes. (Inherited from MethodBase.)
IsFamilyAndAssembly Gets a value that indicates whether the visibility of this method or constructor is described by MethodAttributes..::.FamANDAssem; that is, the method or constructor can be called by derived classes, but only if they are in the same assembly. (Inherited from MethodBase.)
IsFamilyOrAssembly Gets a value that indicates whether the potential visibility of this method or constructor is described by MethodAttributes..::.FamORAssem; that is, the method or constructor can be called by derived classes wherever they are, and by classes in the same assembly. (Inherited from MethodBase.)
IsFinal Gets a value that indicates whether this method is final (NotOverridable in Visual Basic). (Inherited from MethodBase.)
IsGenericMethod Gets a value that indicates whether the method is generic. (Inherited from MethodBase.)
IsGenericMethodDefinition Gets a value that indicates whether the method is a generic method definition. (Inherited from MethodBase.)
IsHideBySig Gets a value that indicates whether only a member of the same kind with exactly the same signature is hidden in the derived class. (Inherited from MethodBase.)
IsPrivate Gets a value that indicates whether this member is private. (Inherited from MethodBase.)
IsPublic Gets a value that indicates whether this is a public method. (Inherited from MethodBase.)
IsSpecialName Gets a value that indicates whether this method has a special name. (Inherited from MethodBase.)
IsStatic Gets a value that indicates whether the method is static (Shared in Visual Basic). (Inherited from MethodBase.)
IsVirtual Gets a value that indicates whether the method is virtual (Overridable in Visual Basic). (Inherited from MethodBase.)
MemberType Gets a MemberTypes value indicating that this member is a constructor. (Overrides MemberInfo..::.MemberType.)
MetadataToken Gets a value that identifies a metadata element. (Inherited from MemberInfo.)
MethodHandle Gets a handle to the internal metadata representation of a method. (Inherited from MethodBase.)
MethodImplementationFlags Gets the MethodImplAttributes flags that specify the attributes of a method implementation. (Inherited from MethodBase.)
Module Gets the module in which the type that declares the member represented by the current MemberInfo is defined. (Inherited from MemberInfo.)
Name Gets the name of the current member. (Inherited from MemberInfo.)
ReflectedType Gets the class object that was used to obtain this instance of MemberInfo. (Inherited from MemberInfo.)

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Methods

Name Description
Equals Returns a value that indicates whether this instance is equal to a specified object. (Overrides MethodBase..::.Equals(Object).)
Finalize Allows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.)
GetCustomAttributes(Boolean) When overridden in a derived class, returns an array of all custom attributes applied to this member. (Inherited from MemberInfo.)
GetCustomAttributes(Type, Boolean) When overridden in a derived class, returns an array of custom attributes applied to this member and identified by Type. (Inherited from MemberInfo.)
GetGenericArguments Returns an array of Type objects that represent the type arguments of a generic method or the type parameters of a generic method definition. (Inherited from MethodBase.)
GetHashCode Returns the hash code for this instance. (Overrides MethodBase..::.GetHashCode()()().)
GetMethodImplementationFlags When overridden in a derived class, returns the MethodImplAttributes flags. (Inherited from MethodBase.)
GetParameters When overridden in a derived class, gets the parameters of this method or constructor. (Inherited from MethodBase.)
GetType Gets the Type of the current instance. (Inherited from Object.)
Invoke(array<Object>[]()[]) Invokes the current constructor with the specified arguments.
Invoke(Object, array<Object>[]()[]) Invokes the method or constructor represented by the current instance, using the specified parameters. (Inherited from MethodBase.)
Invoke(BindingFlags, Binder, array<Object>[]()[], CultureInfo) When implemented in a derived class, invokes the current constructor with the specified arguments, using the specified binder and culture to validate the argument types.
Invoke(Object, BindingFlags, Binder, array<Object>[]()[], CultureInfo) When overridden in a derived class, invokes the reflected method or constructor with the given parameters. (Inherited from MethodBase.)
IsDefined When overridden in a derived class, indicates whether one or more attributes of the specified type or of its derived types is applied to this member. (Inherited from MemberInfo.)
MemberwiseClone Creates a shallow copy of the current Object. (Inherited from Object.)
ToString Returns a string that represents the current object. (Inherited from Object.)

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Extension Methods

Name Description
GetCustomAttribute(Type) Overloaded. Retrieves a custom attribute of a specified type that is applied to a specified member. (Defined by CustomAttributeExtensions.)
GetCustomAttribute(Type, Boolean) Overloaded. Retrieves a custom attribute of a specified type that is applied to a specified member, and optionally inspects the ancestors of that member. (Defined by CustomAttributeExtensions.)
GetCustomAttribute<(Of <(T>)>)()()() Overloaded. Retrieves a custom attribute of a specified type that is applied to a specified member. (Defined by CustomAttributeExtensions.)
GetCustomAttribute<(Of <(T>)>)(Boolean) Overloaded. Retrieves a custom attribute of a specified type that is applied to a specified member, and optionally inspects the ancestors of that member. (Defined by CustomAttributeExtensions.)
GetCustomAttributes()()() Overloaded. Retrieves a collection of custom attributes that are applied to a specified member. (Defined by CustomAttributeExtensions.)
GetCustomAttributes(Type) Overloaded. Retrieves a collection of custom attributes of a specified type that are applied to a specified member. (Defined by CustomAttributeExtensions.)
GetCustomAttributes<(Of <(T>)>)()()() Overloaded. Retrieves a collection of custom attributes of a specified type that are applied to a specified member. (Defined by CustomAttributeExtensions.)
GetCustomAttributes<(Of <(T>)>)(Boolean) Overloaded. Retrieves a collection of custom attributes of a specified type that are applied to a specified member, and optionally inspects the ancestors of that member. (Defined by CustomAttributeExtensions.)
IsDefined Indicates whether custom attributes of a specified type are applied to a specified member. (Defined by CustomAttributeExtensions.)

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Fields

Name Description
ConstructorName Represents the name of the class constructor method as it is stored in metadata. This name is always ".ctor". This field is read-only.
TypeConstructorName Represents the name of the type constructor method as it is stored in metadata. This name is always ".cctor". This property is read-only.

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Remarks

In Windows Phone, you cannot derive from this type.

ConstructorInfo is used to discover the attributes of a constructor and to invoke a constructor. Objects are created by calling Invoke on a ConstructorInfo returned by either the GetConstructors or GetConstructor method of a Type object.

Note

ConstructorInfo inherits several members from MethodBase, such as IsGenericMethod, that can be used to examine generic methods. Constructors cannot be generic, so these members return false or nullNothingnullptra null reference (Nothing in Visual Basic).

Version Notes

Windows Phone

If you call a static constructor using reflection, the application throws ArgumentException instead of MethodAccessException.

Examples

The following example uses ConstructorInfo with GetConstructor and BindingFlags to find the constructors that match the specified search criteria.

Public Class Example
    Public Sub New(ByVal i As Integer)
    End Sub
    Public Shared Sub Demo(outputBlock As System.Windows.Controls.TextBlock)
        Try
            Dim myType As Type = GetType(Example)
            Dim types(0) As Type
            types(0) = GetType(Integer)
            ' Get the public instance constructor that takes an integer parameter.
            Dim constructorInfoObj As ConstructorInfo = _
                        myType.GetConstructor(BindingFlags.Instance Or _
                        BindingFlags.Public, Nothing, types, Nothing)
            If Not (constructorInfoObj Is Nothing) Then
                outputBlock.Text += "The constructor of Example that ".ToString()  + _
                                  "is a public instance method and takes an ".ToString()  + _
                                  "integer as a parameter is: " + Environment.NewLine
                outputBlock.Text += constructorInfoObj.ToString() + Environment.NewLine
            Else
                outputBlock.Text += "The constructor Example that ".ToString()  + _
                                  "is a public instance method and takes an ".ToString()  + _
                                  "integer as a parameter is not available." + Environment.NewLine
            End If
        Catch e As ArgumentNullException
            outputBlock.Text += "ArgumentNullException: ".ToString()  + e.Message.ToString() + Environment.NewLine
        Catch e As ArgumentException
            outputBlock.Text += "ArgumentException: ".ToString()  + e.Message.ToString() + Environment.NewLine
        Catch e As SecurityException
            outputBlock.Text += "SecurityException: ".ToString()  + e.Message.ToString() + Environment.NewLine
        Catch e As Exception
            outputBlock.Text += "Exception: ".ToString()  + e.Message.ToString() + Environment.NewLine
        End Try
    End Sub
End Class
using System;
using System.Reflection;
using System.Security;

public class Example
{
    public Example(int i){}
    public static void Demo(System.Windows.Controls.TextBlock outputBlock)
    {
        try
        {
            Type  myType = typeof(Example);
            Type[] types = new Type[1];
            types[0] = typeof(int);
            // Get the public instance constructor that takes an integer parameter.
            ConstructorInfo constructorInfoObj = myType.GetConstructor(
                BindingFlags.Instance | BindingFlags.Public, null, types, null);
            if(constructorInfoObj != null)
            {
                outputBlock.Text += "The constructor of Example that is a public " +
                    "instance method and takes an integer as a parameter is: " + Environment.NewLine;
                outputBlock.Text += constructorInfoObj.ToString() + Environment.NewLine;
            }
            else
            {
                outputBlock.Text += "The constructor of Example that is a public instance " +
                    "method and takes an integer as a parameter is not available." + Environment.NewLine;
            }
        }
        catch(ArgumentNullException e)
        {
            outputBlock.Text += "ArgumentNullException: " + e.Message + Environment.NewLine;
        }
        catch(ArgumentException e)
        {
            outputBlock.Text += "ArgumentException: " + e.Message + Environment.NewLine;
        }
        catch(SecurityException e)
        {
            outputBlock.Text += "SecurityException: " + e.Message + Environment.NewLine;
        }
        catch(Exception e)
        {
            outputBlock.Text += "Exception: " + e.Message + Environment.NewLine;
        }
    }
}

Version Information

Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0

Platforms

Windows Phone

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

See Also

Reference

System.Reflection Namespace