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TypeBuilder.GetConstructor Method (Type, ConstructorInfo)

Returns the constructor of the specified constructed generic type that corresponds to the specified constructor of the generic type definition.

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

static member GetConstructor : 
        type:Type * 
        constructor:ConstructorInfo -> ConstructorInfo 

Parameters

type
Type: System.Type
The constructed generic type whose constructor is returned.
constructor
Type: System.Reflection.ConstructorInfo
A constructor on the generic type definition of type, which specifies which constructor of type to return.

Return Value

Type: System.Reflection.ConstructorInfo
A ConstructorInfo object that represents the constructor of type corresponding to constructor, which specifies a constructor belonging to the generic type definition of type.

ExceptionCondition
ArgumentException

type does not represent a generic type.

-or-

type is not of type TypeBuilder.

-or-

The declaring type of constructor is not a generic type definition.

-or-

The declaring type of constructor is not the generic type definition of type.

The GetConstructor method provides a way to get a ConstructorInfo object that represents a constructor of a constructed generic type whose generic type definition is represented by a TypeBuilder object.

For example, suppose you have a TypeBuilder object that represents the type G<T> in C# syntax (G(Of T) in Visual Basic, generic <T> ref class G in C++) and a ConstructorBuilder object that represents a constructor of G<T>. Suppose that G<T> has a generic method with type parameter U that creates an instance of the constructed type G<U>. In order to emit the code to create an instance of the constructed type, you need a ConstructorInfo object that represents the constructor of this constructed type — in other words, that creates an instance of G<U>. To do this, first call the MakeGenericType method on the TypeBuilder object, specifying the GenericTypeParameterBuilder object that represents U as the type argument. Then call the GetConstructor method with the return value of the MakeGenericType method as parameter type and the ConstructorBuilder object that represents the constructor of G<U> as parameter constructor. The return value is the ConstructorInfo object you need to emit the function call. The code example demonstrates this scenario.

The following code example contains source code for a generic class named Sample that has a type parameter named T. The class has a field named Field, of type T, and a generic method named GM with its own type parameter, named U. Method GM creates an instance of Sample, substituting its own type parameter U for the type parameter of Sample, and stores its input parameter in Field. This source code is compiled but not used; you can view it with the Ildasm.exe (MSIL Disassembler) and compare it to the code emitted by class Example.

The code in class Example demonstrates the use of the GetConstructor method to emit generic code. The Main method of class Example creates a dynamic assembly containing a class named Sample and uses the DefineGenericParameters method to make it generic by adding a type parameter named T. A default constructor and a field named Field, of type T, are added to class Sample. A method GM is added and turned into a generic method by using the MethodBuilder.DefineGenericParameters method. The type parameter of GM is named U. After the type parameter is defined, the signature of GM is added by using the MethodBuilder.SetSignature method. There is no return type and no required or custom modifiers, so all the parameters of this method are a null reference (Nothing in Visual Basic) except parameterTypes; parameterTypes sets the type of the method's only parameter to U, the method's generic type parameter. The body of the method creates an instance of the constructed type Sample<U> (Sample(Of U) in Visual Basic), assigns the method's parameter to Field, and then prints the value of Field. The GetConstructor method is used to create a ConstructorInfo that represents the default constructor of the constructed generic type Sample<U> in the OpCodes.Newobj instruction that creates the instance.

A dummy type is defined to hold the entry-point method Main. In the body of Main, the static GM method is invoked on the constructed generic type Sample<int> (Sample(Of Integer) in Visual Basic), with type String substituted for U.

When the code example is run, it saves the emitted assembly as TypeBuilderGetFieldExample.exe. You can run TypeBuilderGetFieldExample.exe, and you can use the Ildasm.exe (MSIL Disassembler) to compare the emitted code with the code for the Sample class that is compiled into the code example itself.

No code example is currently available or this language may not be supported.

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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