Procedura: Creare una classe usando CodeDOM

Le procedure seguenti illustrano come creare e compilare un grafo CodeDOM che genera una classe contenente due campi, tre proprietà, un metodo, un costruttore e un punto di ingresso.

1. Creare un'applicazione console che userà codice CodeDOM per generare il codice sorgente per una classe.

   In questo esempio la classe generatrice è denominata Sample e il codice generato è una classe denominata CodeDOMCreatedClass in un file denominato SampleCode.

2. Nella classe generatrice inizializzare il grafo CodeDOM e usare metodi CodeDOM per definire i membri, il costruttore e il punto di ingresso (metodo Main) della classe generata.

   In questo esempio la classe generata ha due campi, tre proprietà, un costruttore, un metodo e un metodo Main.

3. Nella classe generatrice creare un provider di codice specifico del linguaggio e chiamare il relativo metodo GenerateCodeFromCompileUnit per generare il codice dal grafo.

4. Compilare ed eseguire l'applicazione per generare il codice.

   In questo esempio il codice generato è contenuto in un file denominato SampleCode. Compilare ed eseguire il codice per visualizzare l'output di esempio.

Creare l'applicazione che eseguirà il codice CodeDOM

Creare una classe di applicazione console in cui sarà contenuto il codice CodeDOM. Definire i campi globali da usare nella classe per fare riferimento all'assembly (CodeCompileUnit) e alla classe (CodeTypeDeclaration), specificare il nome del file di origine generato e dichiarare il metodo Main.

using System;
using System.Reflection;
using System.IO;
using System.CodeDom;
using System.CodeDom.Compiler;
using Microsoft.CSharp;

namespace SampleCodeDom
{
    class Sample
    {
        CodeCompileUnit targetUnit;
        CodeTypeDeclaration targetClass;
        private const string outputFileName = "SampleCode.cs";
        static void Main(string[] args)
        {
        }
    }
}

Imports System.Reflection
Imports System.IO
Imports System.CodeDom
Imports System.CodeDom.Compiler
Imports Microsoft.CSharp



Class Sample
    Private targetUnit As CodeCompileUnit
    Private targetClass As CodeTypeDeclaration
    Private Const outputFileName As String = "SampleCode.vb"

    Shared Sub Main(ByVal args() As String)

    End Sub
End Class

Inizializzare il grafico CodeDOM

Nel costruttore della classe di applicazione console inizializzare l'assembly e la classe, quindi aggiungere le dichiarazioni appropriate al grafo CodeDOM.

public Sample()
{
    targetUnit = new CodeCompileUnit();
    CodeNamespace samples = new CodeNamespace("CodeDOMSample");
    samples.Imports.Add(new CodeNamespaceImport("System"));
    targetClass = new CodeTypeDeclaration("CodeDOMCreatedClass");
    targetClass.IsClass = true;
    targetClass.TypeAttributes =
        TypeAttributes.Public | TypeAttributes.Sealed;
    samples.Types.Add(targetClass);
    targetUnit.Namespaces.Add(samples);
}

Public Sub New()
    targetUnit = New CodeCompileUnit()
    Dim samples As New CodeNamespace("CodeDOMSample")
    samples.Imports.Add(New CodeNamespaceImport("System"))
    targetClass = New CodeTypeDeclaration("CodeDOMCreatedClass")
    targetClass.IsClass = True
    targetClass.TypeAttributes = _
        TypeAttributes.Public Or TypeAttributes.Sealed
    samples.Types.Add(targetClass)
    targetUnit.Namespaces.Add(samples)

End Sub

Aggiungere membri al grafico CodeDOM

• Aggiungere campi al grafo CodeDOM aggiungendo oggetti CodeMemberField alla proprietà Members della classe.

  public void AddFields()
  {
      // Declare the widthValue field.
      CodeMemberField widthValueField = new CodeMemberField();
      widthValueField.Attributes = MemberAttributes.Private;
      widthValueField.Name = "widthValue";
      widthValueField.Type = new CodeTypeReference(typeof(System.Double));
      widthValueField.Comments.Add(new CodeCommentStatement(
          "The width of the object."));
      targetClass.Members.Add(widthValueField);
  
      // Declare the heightValue field
      CodeMemberField heightValueField = new CodeMemberField();
      heightValueField.Attributes = MemberAttributes.Private;
      heightValueField.Name = "heightValue";
      heightValueField.Type =
          new CodeTypeReference(typeof(System.Double));
      heightValueField.Comments.Add(new CodeCommentStatement(
          "The height of the object."));
      targetClass.Members.Add(heightValueField);
  }
  

  Public Sub AddFields()
      ' Declare the widthValue field.
      Dim widthValueField As New CodeMemberField()
      widthValueField.Attributes = MemberAttributes.Private
      widthValueField.Name = "widthValue"
      widthValueField.Type = _
          New CodeTypeReference(GetType(System.Double))
      widthValueField.Comments.Add(New CodeCommentStatement( _
          "The width of the object."))
      targetClass.Members.Add(widthValueField)
  
      ' Declare the heightValue field
      Dim heightValueField As New CodeMemberField()
      heightValueField.Attributes = MemberAttributes.Private
      heightValueField.Name = "heightValue"
      heightValueField.Type = _
          New CodeTypeReference(GetType(System.Double))
      heightValueField.Comments.Add(New CodeCommentStatement( _
          "The height of the object."))
      targetClass.Members.Add(heightValueField)
  
  End Sub
  

• Aggiungere proprietà al grafo CodeDOM aggiungendo oggetti CodeMemberProperty alla proprietà Members della classe.

  public void AddProperties()
  {
      // Declare the read-only Width property.
      CodeMemberProperty widthProperty = new CodeMemberProperty();
      widthProperty.Attributes =
          MemberAttributes.Public | MemberAttributes.Final;
      widthProperty.Name = "Width";
      widthProperty.HasGet = true;
      widthProperty.Type = new CodeTypeReference(typeof(System.Double));
      widthProperty.Comments.Add(new CodeCommentStatement(
          "The Width property for the object."));
      widthProperty.GetStatements.Add(new CodeMethodReturnStatement(
          new CodeFieldReferenceExpression(
          new CodeThisReferenceExpression(), "widthValue")));
      targetClass.Members.Add(widthProperty);
  
      // Declare the read-only Height property.
      CodeMemberProperty heightProperty = new CodeMemberProperty();
      heightProperty.Attributes =
          MemberAttributes.Public | MemberAttributes.Final;
      heightProperty.Name = "Height";
      heightProperty.HasGet = true;
      heightProperty.Type = new CodeTypeReference(typeof(System.Double));
      heightProperty.Comments.Add(new CodeCommentStatement(
          "The Height property for the object."));
      heightProperty.GetStatements.Add(new CodeMethodReturnStatement(
          new CodeFieldReferenceExpression(
          new CodeThisReferenceExpression(), "heightValue")));
      targetClass.Members.Add(heightProperty);
  
      // Declare the read only Area property.
      CodeMemberProperty areaProperty = new CodeMemberProperty();
      areaProperty.Attributes =
          MemberAttributes.Public | MemberAttributes.Final;
      areaProperty.Name = "Area";
      areaProperty.HasGet = true;
      areaProperty.Type = new CodeTypeReference(typeof(System.Double));
      areaProperty.Comments.Add(new CodeCommentStatement(
          "The Area property for the object."));
  
      // Create an expression to calculate the area for the get accessor
      // of the Area property.
      CodeBinaryOperatorExpression areaExpression =
          new CodeBinaryOperatorExpression(
          new CodeFieldReferenceExpression(
          new CodeThisReferenceExpression(), "widthValue"),
          CodeBinaryOperatorType.Multiply,
          new CodeFieldReferenceExpression(
          new CodeThisReferenceExpression(), "heightValue"));
      areaProperty.GetStatements.Add(
          new CodeMethodReturnStatement(areaExpression));
      targetClass.Members.Add(areaProperty);
  }
  

  Public Sub AddProperties()
      ' Declare the read only Width property.
      Dim widthProperty As New CodeMemberProperty()
      widthProperty.Attributes = _
          MemberAttributes.Public Or MemberAttributes.Final
      widthProperty.Name = "Width"
      widthProperty.HasGet = True
      widthProperty.Type = New CodeTypeReference(GetType(System.Double))
      widthProperty.Comments.Add(New CodeCommentStatement( _
          "The width property for the object."))
      widthProperty.GetStatements.Add(New CodeMethodReturnStatement( _
          New CodeFieldReferenceExpression( _
          New CodeThisReferenceExpression(), "widthValue")))
      targetClass.Members.Add(widthProperty)
  
      ' Declare the read-only Height property.
      Dim heightProperty As New CodeMemberProperty()
      heightProperty.Attributes = _
          MemberAttributes.Public Or MemberAttributes.Final
      heightProperty.Name = "Height"
      heightProperty.HasGet = True
      heightProperty.Type = New CodeTypeReference(GetType(System.Double))
      heightProperty.Comments.Add(New CodeCommentStatement( _
          "The Height property for the object."))
      heightProperty.GetStatements.Add(New CodeMethodReturnStatement( _
          New CodeFieldReferenceExpression( _
          New CodeThisReferenceExpression(), "heightValue")))
      targetClass.Members.Add(heightProperty)
  
      ' Declare the read only Area property.
      Dim areaProperty As New CodeMemberProperty()
      areaProperty.Attributes = _
          MemberAttributes.Public Or MemberAttributes.Final
      areaProperty.Name = "Area"
      areaProperty.HasGet = True
      areaProperty.Type = New CodeTypeReference(GetType(System.Double))
      areaProperty.Comments.Add(New CodeCommentStatement( _
          "The Area property for the object."))
  
      ' Create an expression to calculate the area for the get accessor
      ' of the Area property.
      Dim areaExpression As New CodeBinaryOperatorExpression( _
          New CodeFieldReferenceExpression( _
          New CodeThisReferenceExpression(), "widthValue"), _
          CodeBinaryOperatorType.Multiply, _
          New CodeFieldReferenceExpression( _
          New CodeThisReferenceExpression(), "heightValue"))
      areaProperty.GetStatements.Add( _
          New CodeMethodReturnStatement(areaExpression))
      targetClass.Members.Add(areaProperty)
  
  End Sub
  

• Aggiungere un metodo al grafo CodeDOM aggiungendo un oggetto CodeMemberMethod alla proprietà Members della classe.

  public void AddMethod()
  {
      // Declaring a ToString method
      CodeMemberMethod toStringMethod = new CodeMemberMethod();
      toStringMethod.Attributes =
          MemberAttributes.Public | MemberAttributes.Override;
      toStringMethod.Name = "ToString";
      toStringMethod.ReturnType =
          new CodeTypeReference(typeof(System.String));
  
      CodeFieldReferenceExpression widthReference =
          new CodeFieldReferenceExpression(
          new CodeThisReferenceExpression(), "Width");
      CodeFieldReferenceExpression heightReference =
          new CodeFieldReferenceExpression(
          new CodeThisReferenceExpression(), "Height");
      CodeFieldReferenceExpression areaReference =
          new CodeFieldReferenceExpression(
          new CodeThisReferenceExpression(), "Area");
  
      // Declaring a return statement for method ToString.
      CodeMethodReturnStatement returnStatement =
          new CodeMethodReturnStatement();
  
      // This statement returns a string representation of the width,
      // height, and area.
      string formattedOutput = "The object:" + Environment.NewLine +
          " width = {0}," + Environment.NewLine +
          " height = {1}," + Environment.NewLine +
          " area = {2}";
      returnStatement.Expression =
          new CodeMethodInvokeExpression(
          new CodeTypeReferenceExpression("System.String"), "Format",
          new CodePrimitiveExpression(formattedOutput),
          widthReference, heightReference, areaReference);
      toStringMethod.Statements.Add(returnStatement);
      targetClass.Members.Add(toStringMethod);
  }
  

  Public Sub AddMethod()
      ' Declaring a ToString method.
      Dim toStringMethod As New CodeMemberMethod()
      toStringMethod.Attributes = _
          MemberAttributes.Public Or MemberAttributes.Override
      toStringMethod.Name = "ToString"
      toStringMethod.ReturnType = _
          New CodeTypeReference(GetType(System.String))
  
      Dim widthReference As New CodeFieldReferenceExpression( _
          New CodeThisReferenceExpression(), "Width")
      Dim heightReference As New CodeFieldReferenceExpression( _
          New CodeThisReferenceExpression(), "Height")
      Dim areaReference As New CodeFieldReferenceExpression( _
          New CodeThisReferenceExpression(), "Area")
  
      ' Declaring a return statement for method ToString.
      Dim returnStatement As New CodeMethodReturnStatement()
  
      ' This statement returns a string representation of the width,
      ' height, and area.
      Dim formattedOutput As String = "The object:" & Environment.NewLine _
          & " width = {0}," & Environment.NewLine & " height = {1}," _
          & Environment.NewLine & " area = {2}"
      returnStatement.Expression = New CodeMethodInvokeExpression( _
          New CodeTypeReferenceExpression("System.String"), "Format", _
          New CodePrimitiveExpression(formattedOutput), widthReference, _
          heightReference, areaReference)
      toStringMethod.Statements.Add(returnStatement)
      targetClass.Members.Add(toStringMethod)
  
  End Sub
  

• Aggiungere un costruttore al grafo CodeDOM aggiungendo un oggetto CodeConstructor alla proprietà Members della classe.

  public void AddConstructor()
  {
      // Declare the constructor
      CodeConstructor constructor = new CodeConstructor();
      constructor.Attributes =
          MemberAttributes.Public | MemberAttributes.Final;
  
      // Add parameters.
      constructor.Parameters.Add(new CodeParameterDeclarationExpression(
          typeof(System.Double), "width"));
      constructor.Parameters.Add(new CodeParameterDeclarationExpression(
          typeof(System.Double), "height"));
  
      // Add field initialization logic
      CodeFieldReferenceExpression widthReference =
          new CodeFieldReferenceExpression(
          new CodeThisReferenceExpression(), "widthValue");
      constructor.Statements.Add(new CodeAssignStatement(widthReference,
          new CodeArgumentReferenceExpression("width")));
      CodeFieldReferenceExpression heightReference =
          new CodeFieldReferenceExpression(
          new CodeThisReferenceExpression(), "heightValue");
      constructor.Statements.Add(new CodeAssignStatement(heightReference,
          new CodeArgumentReferenceExpression("height")));
      targetClass.Members.Add(constructor);
  }
  

  Public Sub AddConstructor()
      ' Declare the constructor
      Dim constructor As New CodeConstructor()
      constructor.Attributes = _
          MemberAttributes.Public Or MemberAttributes.Final
  
      ' Add parameters.
      constructor.Parameters.Add( _
          New CodeParameterDeclarationExpression( _
          GetType(System.Double), "width"))
      constructor.Parameters.Add( _
          New CodeParameterDeclarationExpression( _
          GetType(System.Double), "height"))
  
      ' Add field initialization logic
      Dim widthReference As New CodeFieldReferenceExpression( _
          New CodeThisReferenceExpression(), "widthValue")
      constructor.Statements.Add(New CodeAssignStatement( _
          widthReference, New CodeArgumentReferenceExpression("width")))
      Dim heightReference As New CodeFieldReferenceExpression( _
          New CodeThisReferenceExpression(), "heightValue")
      constructor.Statements.Add( _
          New CodeAssignStatement(heightReference, _
          New CodeArgumentReferenceExpression("height")))
      targetClass.Members.Add(constructor)
  
  End Sub
  

• Aggiungere un punto di ingresso al grafo CodeDOM aggiungendo un oggetto CodeEntryPointMethod alla proprietà Members della classe.

  public void AddEntryPoint()
  {
      CodeEntryPointMethod start = new CodeEntryPointMethod();
      CodeObjectCreateExpression objectCreate =
          new CodeObjectCreateExpression(
          new CodeTypeReference("CodeDOMCreatedClass"),
          new CodePrimitiveExpression(5.3),
          new CodePrimitiveExpression(6.9));
  
      // Add the statement:
      // "CodeDOMCreatedClass testClass =
      //     new CodeDOMCreatedClass(5.3, 6.9);"
      start.Statements.Add(new CodeVariableDeclarationStatement(
          new CodeTypeReference("CodeDOMCreatedClass"), "testClass",
          objectCreate));
  
      // Creat the expression:
      // "testClass.ToString()"
      CodeMethodInvokeExpression toStringInvoke =
          new CodeMethodInvokeExpression(
          new CodeVariableReferenceExpression("testClass"), "ToString");
  
      // Add a System.Console.WriteLine statement with the previous
      // expression as a parameter.
      start.Statements.Add(new CodeMethodInvokeExpression(
          new CodeTypeReferenceExpression("System.Console"),
          "WriteLine", toStringInvoke));
      targetClass.Members.Add(start);
  }
  

  Public Sub AddEntryPoint()
      Dim start As New CodeEntryPointMethod()
      Dim objectCreate As New CodeObjectCreateExpression( _
          New CodeTypeReference("CodeDOMCreatedClass"), _
          New CodePrimitiveExpression(5.3), _
          New CodePrimitiveExpression(6.9))
  
      ' Add the statement:
      ' "CodeDOMCreatedClass testClass = _
      '     new CodeDOMCreatedClass(5.3, 6.9);"
      start.Statements.Add(New CodeVariableDeclarationStatement( _
          New CodeTypeReference("CodeDOMCreatedClass"), _
          "testClass", objectCreate))
  
      ' Creat the expression:
      ' "testClass.ToString()"
      Dim toStringInvoke As New CodeMethodInvokeExpression( _
          New CodeVariableReferenceExpression("testClass"), "ToString")
  
      ' Add a System.Console.WriteLine statement with the previous 
      ' expression as a parameter.
      start.Statements.Add(New CodeMethodInvokeExpression( _
          New CodeTypeReferenceExpression("System.Console"), _
          "WriteLine", toStringInvoke))
      targetClass.Members.Add(start)
  
  End Sub
  

Generare il codice dal grafico CodeDOM

Generare codice sorgente dal grafo CodeDOM chiamando il metodo GenerateCodeFromCompileUnit.

public void GenerateCSharpCode(string fileName)
{
    CodeDomProvider provider = CodeDomProvider.CreateProvider("CSharp");
    CodeGeneratorOptions options = new CodeGeneratorOptions();
    options.BracingStyle = "C";
    using (StreamWriter sourceWriter = new StreamWriter(fileName))
    {
        provider.GenerateCodeFromCompileUnit(
            targetUnit, sourceWriter, options);
    }
}

Public Sub GenerateVBCode(ByVal fileName As String)
    Dim provider As CodeDomProvider
    provider = CodeDomProvider.CreateProvider("VisualBasic")
    Dim options As New CodeGeneratorOptions()
    Dim sourceWriter As New StreamWriter(fileName)
    Try
        provider.GenerateCodeFromCompileUnit( _
            targetUnit, sourceWriter, options)
    Finally
        sourceWriter.Dispose()
    End Try

End Sub

Creare il grafico e generare il codice

1. Aggiungere i metodi creati nei passaggi precedenti al metodo Main definito nel primo passaggio.

   static void Main()
   {
       Sample sample = new Sample();
       sample.AddFields();
       sample.AddProperties();
       sample.AddMethod();
       sample.AddConstructor();
       sample.AddEntryPoint();
       sample.GenerateCSharpCode(outputFileName);
   }
   

       Shared Sub Main()
           Dim sample As New Sample()
           sample.AddFields()
           sample.AddProperties()
           sample.AddMethod()
           sample.AddConstructor()
           sample.AddEntryPoint()
           sample.GenerateVBCode(outputFileName)
   
       End Sub
   End Class
   

2. Compilare ed eseguire la classe generatrice.

Esempio

L'esempio di codice seguente illustra il codice dei passaggi precedenti.

using System;
using System.Reflection;
using System.IO;
using System.CodeDom;
using System.CodeDom.Compiler;
using Microsoft.CSharp;

namespace SampleCodeDom
{
    /// <summary>
    /// This code example creates a graph using a CodeCompileUnit and
    /// generates source code for the graph using the CSharpCodeProvider.
    /// </summary>
    class Sample
    {
        /// <summary>
        /// Define the compile unit to use for code generation.
        /// </summary>
        CodeCompileUnit targetUnit;

        /// <summary>
        /// The only class in the compile unit. This class contains 2 fields,
        /// 3 properties, a constructor, an entry point, and 1 simple method.
        /// </summary>
        CodeTypeDeclaration targetClass;

        /// <summary>
        /// The name of the file to contain the source code.
        /// </summary>
        private const string outputFileName = "SampleCode.cs";

        /// <summary>
        /// Define the class.
        /// </summary>
        public Sample()
        {
            targetUnit = new CodeCompileUnit();
            CodeNamespace samples = new CodeNamespace("CodeDOMSample");
            samples.Imports.Add(new CodeNamespaceImport("System"));
            targetClass = new CodeTypeDeclaration("CodeDOMCreatedClass");
            targetClass.IsClass = true;
            targetClass.TypeAttributes =
                TypeAttributes.Public | TypeAttributes.Sealed;
            samples.Types.Add(targetClass);
            targetUnit.Namespaces.Add(samples);
        }

        /// <summary>
        /// Adds two fields to the class.
        /// </summary>
        public void AddFields()
        {
            // Declare the widthValue field.
            CodeMemberField widthValueField = new CodeMemberField();
            widthValueField.Attributes = MemberAttributes.Private;
            widthValueField.Name = "widthValue";
            widthValueField.Type = new CodeTypeReference(typeof(System.Double));
            widthValueField.Comments.Add(new CodeCommentStatement(
                "The width of the object."));
            targetClass.Members.Add(widthValueField);

            // Declare the heightValue field
            CodeMemberField heightValueField = new CodeMemberField();
            heightValueField.Attributes = MemberAttributes.Private;
            heightValueField.Name = "heightValue";
            heightValueField.Type =
                new CodeTypeReference(typeof(System.Double));
            heightValueField.Comments.Add(new CodeCommentStatement(
                "The height of the object."));
            targetClass.Members.Add(heightValueField);
        }
        /// <summary>
        /// Add three properties to the class.
        /// </summary>
        public void AddProperties()
        {
            // Declare the read-only Width property.
            CodeMemberProperty widthProperty = new CodeMemberProperty();
            widthProperty.Attributes =
                MemberAttributes.Public | MemberAttributes.Final;
            widthProperty.Name = "Width";
            widthProperty.HasGet = true;
            widthProperty.Type = new CodeTypeReference(typeof(System.Double));
            widthProperty.Comments.Add(new CodeCommentStatement(
                "The Width property for the object."));
            widthProperty.GetStatements.Add(new CodeMethodReturnStatement(
                new CodeFieldReferenceExpression(
                new CodeThisReferenceExpression(), "widthValue")));
            targetClass.Members.Add(widthProperty);

            // Declare the read-only Height property.
            CodeMemberProperty heightProperty = new CodeMemberProperty();
            heightProperty.Attributes =
                MemberAttributes.Public | MemberAttributes.Final;
            heightProperty.Name = "Height";
            heightProperty.HasGet = true;
            heightProperty.Type = new CodeTypeReference(typeof(System.Double));
            heightProperty.Comments.Add(new CodeCommentStatement(
                "The Height property for the object."));
            heightProperty.GetStatements.Add(new CodeMethodReturnStatement(
                new CodeFieldReferenceExpression(
                new CodeThisReferenceExpression(), "heightValue")));
            targetClass.Members.Add(heightProperty);

            // Declare the read only Area property.
            CodeMemberProperty areaProperty = new CodeMemberProperty();
            areaProperty.Attributes =
                MemberAttributes.Public | MemberAttributes.Final;
            areaProperty.Name = "Area";
            areaProperty.HasGet = true;
            areaProperty.Type = new CodeTypeReference(typeof(System.Double));
            areaProperty.Comments.Add(new CodeCommentStatement(
                "The Area property for the object."));

            // Create an expression to calculate the area for the get accessor
            // of the Area property.
            CodeBinaryOperatorExpression areaExpression =
                new CodeBinaryOperatorExpression(
                new CodeFieldReferenceExpression(
                new CodeThisReferenceExpression(), "widthValue"),
                CodeBinaryOperatorType.Multiply,
                new CodeFieldReferenceExpression(
                new CodeThisReferenceExpression(), "heightValue"));
            areaProperty.GetStatements.Add(
                new CodeMethodReturnStatement(areaExpression));
            targetClass.Members.Add(areaProperty);
        }

        /// <summary>
        /// Adds a method to the class. This method multiplies values stored
        /// in both fields.
        /// </summary>
        public void AddMethod()
        {
            // Declaring a ToString method
            CodeMemberMethod toStringMethod = new CodeMemberMethod();
            toStringMethod.Attributes =
                MemberAttributes.Public | MemberAttributes.Override;
            toStringMethod.Name = "ToString";
            toStringMethod.ReturnType =
                new CodeTypeReference(typeof(System.String));

            CodeFieldReferenceExpression widthReference =
                new CodeFieldReferenceExpression(
                new CodeThisReferenceExpression(), "Width");
            CodeFieldReferenceExpression heightReference =
                new CodeFieldReferenceExpression(
                new CodeThisReferenceExpression(), "Height");
            CodeFieldReferenceExpression areaReference =
                new CodeFieldReferenceExpression(
                new CodeThisReferenceExpression(), "Area");

            // Declaring a return statement for method ToString.
            CodeMethodReturnStatement returnStatement =
                new CodeMethodReturnStatement();

            // This statement returns a string representation of the width,
            // height, and area.
            string formattedOutput = "The object:" + Environment.NewLine +
                " width = {0}," + Environment.NewLine +
                " height = {1}," + Environment.NewLine +
                " area = {2}";
            returnStatement.Expression =
                new CodeMethodInvokeExpression(
                new CodeTypeReferenceExpression("System.String"), "Format",
                new CodePrimitiveExpression(formattedOutput),
                widthReference, heightReference, areaReference);
            toStringMethod.Statements.Add(returnStatement);
            targetClass.Members.Add(toStringMethod);
        }
        /// <summary>
        /// Add a constructor to the class.
        /// </summary>
        public void AddConstructor()
        {
            // Declare the constructor
            CodeConstructor constructor = new CodeConstructor();
            constructor.Attributes =
                MemberAttributes.Public | MemberAttributes.Final;

            // Add parameters.
            constructor.Parameters.Add(new CodeParameterDeclarationExpression(
                typeof(System.Double), "width"));
            constructor.Parameters.Add(new CodeParameterDeclarationExpression(
                typeof(System.Double), "height"));

            // Add field initialization logic
            CodeFieldReferenceExpression widthReference =
                new CodeFieldReferenceExpression(
                new CodeThisReferenceExpression(), "widthValue");
            constructor.Statements.Add(new CodeAssignStatement(widthReference,
                new CodeArgumentReferenceExpression("width")));
            CodeFieldReferenceExpression heightReference =
                new CodeFieldReferenceExpression(
                new CodeThisReferenceExpression(), "heightValue");
            constructor.Statements.Add(new CodeAssignStatement(heightReference,
                new CodeArgumentReferenceExpression("height")));
            targetClass.Members.Add(constructor);
        }

        /// <summary>
        /// Add an entry point to the class.
        /// </summary>
        public void AddEntryPoint()
        {
            CodeEntryPointMethod start = new CodeEntryPointMethod();
            CodeObjectCreateExpression objectCreate =
                new CodeObjectCreateExpression(
                new CodeTypeReference("CodeDOMCreatedClass"),
                new CodePrimitiveExpression(5.3),
                new CodePrimitiveExpression(6.9));

            // Add the statement:
            // "CodeDOMCreatedClass testClass =
            //     new CodeDOMCreatedClass(5.3, 6.9);"
            start.Statements.Add(new CodeVariableDeclarationStatement(
                new CodeTypeReference("CodeDOMCreatedClass"), "testClass",
                objectCreate));

            // Creat the expression:
            // "testClass.ToString()"
            CodeMethodInvokeExpression toStringInvoke =
                new CodeMethodInvokeExpression(
                new CodeVariableReferenceExpression("testClass"), "ToString");

            // Add a System.Console.WriteLine statement with the previous
            // expression as a parameter.
            start.Statements.Add(new CodeMethodInvokeExpression(
                new CodeTypeReferenceExpression("System.Console"),
                "WriteLine", toStringInvoke));
            targetClass.Members.Add(start);
        }
        /// <summary>
        /// Generate CSharp source code from the compile unit.
        /// </summary>
        /// <param name="filename">Output file name</param>
        public void GenerateCSharpCode(string fileName)
        {
            CodeDomProvider provider = CodeDomProvider.CreateProvider("CSharp");
            CodeGeneratorOptions options = new CodeGeneratorOptions();
            options.BracingStyle = "C";
            using (StreamWriter sourceWriter = new StreamWriter(fileName))
            {
                provider.GenerateCodeFromCompileUnit(
                    targetUnit, sourceWriter, options);
            }
        }

        /// <summary>
        /// Create the CodeDOM graph and generate the code.
        /// </summary>
        static void Main()
        {
            Sample sample = new Sample();
            sample.AddFields();
            sample.AddProperties();
            sample.AddMethod();
            sample.AddConstructor();
            sample.AddEntryPoint();
            sample.GenerateCSharpCode(outputFileName);
        }
    }
}

Imports System.Reflection
Imports System.IO
Imports System.CodeDom
Imports System.CodeDom.Compiler

' This code example creates a graph using a CodeCompileUnit and  
' generates source code for the graph using the VBCodeProvider.
Class Sample

    ' Define the compile unit to use for code generation. 
    Private targetUnit As CodeCompileUnit

    ' The only class in the compile unit. This class contains 2 fields,
    ' 3 properties, a constructor, an entry point, and 1 simple method. 
    Private targetClass As CodeTypeDeclaration

    ' The name of the file to contain the source code.
    Private Const outputFileName As String = "SampleCode.vb"

    ' Define the class.
    Public Sub New()
        targetUnit = New CodeCompileUnit()
        Dim samples As New CodeNamespace("CodeDOMSample")
        samples.Imports.Add(New CodeNamespaceImport("System"))
        targetClass = New CodeTypeDeclaration("CodeDOMCreatedClass")
        targetClass.IsClass = True
        targetClass.TypeAttributes = _
            TypeAttributes.Public Or TypeAttributes.Sealed
        samples.Types.Add(targetClass)
        targetUnit.Namespaces.Add(samples)

    End Sub

    ' Adds two fields to the class.
    Public Sub AddFields()
        ' Declare the widthValue field.
        Dim widthValueField As New CodeMemberField()
        widthValueField.Attributes = MemberAttributes.Private
        widthValueField.Name = "widthValue"
        widthValueField.Type = _
            New CodeTypeReference(GetType(System.Double))
        widthValueField.Comments.Add(New CodeCommentStatement( _
            "The width of the object."))
        targetClass.Members.Add(widthValueField)

        ' Declare the heightValue field
        Dim heightValueField As New CodeMemberField()
        heightValueField.Attributes = MemberAttributes.Private
        heightValueField.Name = "heightValue"
        heightValueField.Type = _
            New CodeTypeReference(GetType(System.Double))
        heightValueField.Comments.Add(New CodeCommentStatement( _
            "The height of the object."))
        targetClass.Members.Add(heightValueField)

    End Sub

    ' Add three properties to the class.
    Public Sub AddProperties()
        ' Declare the read only Width property.
        Dim widthProperty As New CodeMemberProperty()
        widthProperty.Attributes = _
            MemberAttributes.Public Or MemberAttributes.Final
        widthProperty.Name = "Width"
        widthProperty.HasGet = True
        widthProperty.Type = New CodeTypeReference(GetType(System.Double))
        widthProperty.Comments.Add(New CodeCommentStatement( _
            "The width property for the object."))
        widthProperty.GetStatements.Add(New CodeMethodReturnStatement( _
            New CodeFieldReferenceExpression( _
            New CodeThisReferenceExpression(), "widthValue")))
        targetClass.Members.Add(widthProperty)

        ' Declare the read-only Height property.
        Dim heightProperty As New CodeMemberProperty()
        heightProperty.Attributes = _
            MemberAttributes.Public Or MemberAttributes.Final
        heightProperty.Name = "Height"
        heightProperty.HasGet = True
        heightProperty.Type = New CodeTypeReference(GetType(System.Double))
        heightProperty.Comments.Add(New CodeCommentStatement( _
            "The Height property for the object."))
        heightProperty.GetStatements.Add(New CodeMethodReturnStatement( _
            New CodeFieldReferenceExpression( _
            New CodeThisReferenceExpression(), "heightValue")))
        targetClass.Members.Add(heightProperty)

        ' Declare the read only Area property.
        Dim areaProperty As New CodeMemberProperty()
        areaProperty.Attributes = _
            MemberAttributes.Public Or MemberAttributes.Final
        areaProperty.Name = "Area"
        areaProperty.HasGet = True
        areaProperty.Type = New CodeTypeReference(GetType(System.Double))
        areaProperty.Comments.Add(New CodeCommentStatement( _
            "The Area property for the object."))

        ' Create an expression to calculate the area for the get accessor
        ' of the Area property.
        Dim areaExpression As New CodeBinaryOperatorExpression( _
            New CodeFieldReferenceExpression( _
            New CodeThisReferenceExpression(), "widthValue"), _
            CodeBinaryOperatorType.Multiply, _
            New CodeFieldReferenceExpression( _
            New CodeThisReferenceExpression(), "heightValue"))
        areaProperty.GetStatements.Add( _
            New CodeMethodReturnStatement(areaExpression))
        targetClass.Members.Add(areaProperty)

    End Sub

    ' Adds a method to the class. This method multiplies values stored 
    ' in both fields.
    Public Sub AddMethod()
        ' Declaring a ToString method.
        Dim toStringMethod As New CodeMemberMethod()
        toStringMethod.Attributes = _
            MemberAttributes.Public Or MemberAttributes.Override
        toStringMethod.Name = "ToString"
        toStringMethod.ReturnType = _
            New CodeTypeReference(GetType(System.String))

        Dim widthReference As New CodeFieldReferenceExpression( _
            New CodeThisReferenceExpression(), "Width")
        Dim heightReference As New CodeFieldReferenceExpression( _
            New CodeThisReferenceExpression(), "Height")
        Dim areaReference As New CodeFieldReferenceExpression( _
            New CodeThisReferenceExpression(), "Area")

        ' Declaring a return statement for method ToString.
        Dim returnStatement As New CodeMethodReturnStatement()

        ' This statement returns a string representation of the width,
        ' height, and area.
        Dim formattedOutput As String = "The object:" & Environment.NewLine _
            & " width = {0}," & Environment.NewLine & " height = {1}," _
            & Environment.NewLine & " area = {2}"
        returnStatement.Expression = New CodeMethodInvokeExpression( _
            New CodeTypeReferenceExpression("System.String"), "Format", _
            New CodePrimitiveExpression(formattedOutput), widthReference, _
            heightReference, areaReference)
        toStringMethod.Statements.Add(returnStatement)
        targetClass.Members.Add(toStringMethod)

    End Sub

    ' Add a constructor to the class.
    Public Sub AddConstructor()
        ' Declare the constructor
        Dim constructor As New CodeConstructor()
        constructor.Attributes = _
            MemberAttributes.Public Or MemberAttributes.Final

        ' Add parameters.
        constructor.Parameters.Add( _
            New CodeParameterDeclarationExpression( _
            GetType(System.Double), "width"))
        constructor.Parameters.Add( _
            New CodeParameterDeclarationExpression( _
            GetType(System.Double), "height"))

        ' Add field initialization logic
        Dim widthReference As New CodeFieldReferenceExpression( _
            New CodeThisReferenceExpression(), "widthValue")
        constructor.Statements.Add(New CodeAssignStatement( _
            widthReference, New CodeArgumentReferenceExpression("width")))
        Dim heightReference As New CodeFieldReferenceExpression( _
            New CodeThisReferenceExpression(), "heightValue")
        constructor.Statements.Add( _
            New CodeAssignStatement(heightReference, _
            New CodeArgumentReferenceExpression("height")))
        targetClass.Members.Add(constructor)

    End Sub

    ' Add an entry point to the class.
    Public Sub AddEntryPoint()
        Dim start As New CodeEntryPointMethod()
        Dim objectCreate As New CodeObjectCreateExpression( _
            New CodeTypeReference("CodeDOMCreatedClass"), _
            New CodePrimitiveExpression(5.3), _
            New CodePrimitiveExpression(6.9))

        ' Add the statement:
        ' "CodeDOMCreatedClass testClass = _
        '     new CodeDOMCreatedClass(5.3, 6.9);"
        start.Statements.Add(New CodeVariableDeclarationStatement( _
            New CodeTypeReference("CodeDOMCreatedClass"), _
            "testClass", objectCreate))

        ' Creat the expression:
        ' "testClass.ToString()"
        Dim toStringInvoke As New CodeMethodInvokeExpression( _
            New CodeVariableReferenceExpression("testClass"), "ToString")

        ' Add a System.Console.WriteLine statement with the previous 
        ' expression as a parameter.
        start.Statements.Add(New CodeMethodInvokeExpression( _
            New CodeTypeReferenceExpression("System.Console"), _
            "WriteLine", toStringInvoke))
        targetClass.Members.Add(start)

    End Sub

    ' Generate Visual Basic source code from the compile unit.
    Public Sub GenerateVBCode(ByVal fileName As String)
        Dim provider As CodeDomProvider
        provider = CodeDomProvider.CreateProvider("VisualBasic")
        Dim options As New CodeGeneratorOptions()
        Dim sourceWriter As New StreamWriter(fileName)
        Try
            provider.GenerateCodeFromCompileUnit( _
                targetUnit, sourceWriter, options)
        Finally
            sourceWriter.Dispose()
        End Try

    End Sub

    ' Create the CodeDOM graph and generate the code.
    Shared Sub Main()
        Dim sample As New Sample()
        sample.AddFields()
        sample.AddProperties()
        sample.AddMethod()
        sample.AddConstructor()
        sample.AddEntryPoint()
        sample.GenerateVBCode(outputFileName)

    End Sub
End Class

Quando l'esempio precedente viene compilato ed eseguito, produce il codice sorgente seguente.

//--------------------------------------------------------------------------
// <auto-generated>
//     This code was generated by a tool.
//     Runtime Version:2.0.50727.42
//
//     Changes to this file may cause incorrect behavior and will be lost if
//     the code is regenerated.
// </auto-generated>
//--------------------------------------------------------------------------

namespace CodeDOMSample
{
    using System;


    public sealed class CodeDOMCreatedClass
    {

        // The width of the object.
        private double widthValue;

        // The height of the object.
        private double heightValue;

        public CodeDOMCreatedClass(double width, double height)
        {
            this.widthValue = width;
            this.heightValue = height;
        }

        // The Width property for the object.
        public double Width
        {
            get
            {
                return this.widthValue;
            }
        }

        // The Height property for the object.
        public double Height
        {
            get
            {
                return this.heightValue;
            }
        }

        // The Area property for the object.
        public double Area
        {
            get
            {
                return (this.widthValue * this.heightValue);
            }
        }

        public override string ToString()
        {
            return string.Format(
                "The object:\r\n width = {0},\r\n height = {1},\r\n area = {2}",
                this.Width, this.Height, this.Area);
        }

        public static void Main()
        {
            CodeDOMCreatedClass testClass = new CodeDOMCreatedClass(5.3, 6.9);
            System.Console.WriteLine(testClass.ToString());
        }
    }
}

'--------------------------------------------------------------------------
' <auto-generated>
'     This code was generated by a tool.
'     Runtime Version:2.0.50727.42
'
'     Changes to this file may cause incorrect behavior and will be lost if
'     the code is regenerated.
' </auto-generated>
'--------------------------------------------------------------------------

Option Strict Off
Option Explicit On

Namespace CodeDOMSample
    
    Public NotInheritable Class CodeDOMCreatedClass
        
        'The width of the object.
        Private widthValue As Double
        
        'The height of the object.
        Private heightValue As Double
        
        Public Sub New(ByVal width As Double, ByVal height As Double)
            MyBase.New
            Me.widthValue = width
            Me.heightValue = height
        End Sub
        
        'The width property for the object.
        Public ReadOnly Property Width() As Double
            Get
                Return Me.widthValue
            End Get
        End Property
        
        'The Height property for the object.
        Public ReadOnly Property Height() As Double
            Get
                Return Me.heightValue
            End Get
        End Property
        
        'The Area property for the object.
        Public ReadOnly Property Area() As Double
            Get
                Return (Me.widthValue * Me.heightValue)
            End Get
        End Property
        
        Public Overrides Function ToString() As String
            Return String.Format("The object:"& _
                Global.Microsoft.VisualBasic.ChrW(13)& _
                Global.Microsoft.VisualBasic.ChrW(10)& _
                " width = {0},"&Global.Microsoft.VisualBasic.ChrW(13)& _
                Global.Microsoft.VisualBasic.ChrW(10)& _
                " height = {1},"&Global.Microsoft.VisualBasic.ChrW(13)& _
                Global.Microsoft.VisualBasic.ChrW(10)&" area = {2}", _
                Me.Width, Me.Height, Me.Area)
        End Function
        
        Public Shared Sub Main()
            Dim testClass As CodeDOMCreatedClass = _
                New CodeDOMCreatedClass(5.3, 6.9)
            System.Console.WriteLine(testClass.ToString)
        End Sub
    End Class
End Namespace

Il codice sorgente generato produce l'output seguente quando viene compilato ed eseguito.

The object:
 width = 5.3,
 height = 6.9,
 area = 36.57

Compilazione del codice

• Per essere eseguito correttamente, questo esempio di codice richiede il set di autorizzazioni FullTrust.

Vedi anche

• Uso di CodeDOM
• Generazione e compilazione di codice sorgente a partire da un grafo CodeDOM