Alas no. This is not the goal of an attribute.
Code cannot be run at compile time because, well, the code hasn't been built
yet...
Attributes provide metadata which may be used at runtime but is only
available through reflection on a finished assembly or an instance of a
class. The Attribute based classes can have functional methods but are
usually "instantiated" by the process of reflection and an attribute cannot
alter the form of the code with which it is associated.
An attribute that has construction parameters will be created, instantiated,
when the TypeDescriptor.GetAttributes method is called. An attribute with no
constructor parameters will be instantiated at the moment that the
reflection process discovers an attribute of that type in the metadata. If
the attribute is way down on the list, the construction will take place
after the previous attributes have been created.
Once an attribute is instantiated by the process of reflection you can then
call its methods.
Find a little C# example after my signature...
--
Bob Powell [MVP]
Visual C#, System.Drawing
Ramuseco Limited .NET consulting
http://www.ramuseco.com
Find great Windows Forms articles in Windows Forms Tips and Tricks
http://www.bobpowell.net/tipstricks.htm
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http://www.bobpowell.net/faqmain.htm
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using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
namespace StrangeAttribute
{
/// <summary>
/// Summary description for Form1.
/// </summary>
[
Pork(),
Pork("......Plonk")
]
public class Form1 : System.Windows.Forms.Form
{
private System.Windows.Forms.Button button1;
/// <summary>
/// Required designer variable.
/// </summary>
private System.ComponentModel.Container components = null;
public Form1()
{
//
// Required for Windows Form Designer support
//
InitializeComponent();
//
// TODO: Add any constructor code after InitializeComponent call
//
}
/// <summary>
/// Clean up any resources being used.
/// </summary>
protected override void Dispose( bool disposing )
{
if( disposing )
{
if (components != null)
{
components.Dispose();
}
}
base.Dispose( disposing );
}
#region Windows Form Designer generated code
/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
private void InitializeComponent()
{
this.button1 = new System.Windows.Forms.Button();
this.SuspendLayout();
//
// button1
//
this.button1.Location = new System.Drawing.Point(96, 128);
this.button1.Name = "button1";
this.button1.TabIndex = 0;
this.button1.Text = "Reflect";
this.button1.Click += new System.EventHandler(this.button1_Click);
//
// Form1
//
this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
this.ClientSize = new System.Drawing.Size(292, 266);
this.Controls.Add(this.button1);
this.Name = "Form1";
this.Text = "Form1";
this.ResumeLayout(false);
}
#endregion
/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main()
{
Application.Run(new Form1());
}
private void button1_Click(object sender, System.EventArgs e)
{
System.Diagnostics.Trace.WriteLine("Reflecting");
foreach(Attribute a in TypeDescriptor.GetAttributes(this,true))
{
System.Diagnostics.Trace.WriteLine("Got attribute: "+a.ToString());
if(a.GetType() == typeof(PorkAttribute))
{
((PorkAttribute)a).foo();
}
}
}
}
[
AttributeUsage(AttributeTargets.All, AllowMultiple=true)
]
public class PorkAttribute : Attribute
{
public PorkAttribute()
{
this.Arrgghh("!!");
}
public PorkAttribute(string stuff)
{
MessageBox.Show("This time it worked"+stuff);
}
void Arrgghh(string stuff)
{
MessageBox.Show("Attribute Constructed!!");
}
public void foo()
{
MessageBox.Show("Foo!!");
}
}
}
"Stuart Carnie" <st***********@nospam.nospam> wrote in message
news:OH**************@TK2MSFTNGP04.phx.gbl...
I suspect it's unlikely, but you'll never know until you ask, but are there
any attributes that would allow us to contribute to the compiled output?
e.g.
// this class exists in a separate, compiled assembly for the compiler to
load during compilation
class MyMethodCompiler : Attribute
{
// This is called during compilation
public override void GenerateMethod(MethodBuilder method)
{
// modify the IL that was generated from the compiler
}
}
// some class in a user assembly
class MyClass
{
[MyMethodCompiler]
public void SomeMethod(...)
{
// User code in method
...
...
...
}
}
