Custom AssemblyInfo Attributes

November 28, 2004

To complement my previous post bemoaning the lack of respect for AssemblyInfo, I wanted to illustrate just how easy it is to add a few custom attributes to our AssemblyInfo file:

Imports System
Imports System.Reflection

<Assembly: AssemblyTitle("ASPUnhandledException")> 
<Assembly: AssemblyDescription("ASP.NET unhandled exception handling library")> 
<Assembly: AssemblyCompany("Atwood Heavy Industries")> 
<Assembly: AssemblyCompanyEmail("jatwood@atwoodheavyindustries.com")> 
<Assembly: AssemblyCompanyUrl("http://www.atwoodheavyindustries.com")>
<Assembly: AssemblyProduct("Exception Handling Framework")> 
<Assembly: AssemblyCopyright(" 2004, Atwood Heavy Industries")> 
<Assembly: AssemblyTrademark("All Rights Reserved")> 
<Assembly: CLSCompliant(True)> 

<Assembly: AssemblyVersion("2.1.*")> 

To get the custom attributes AssemblyCompanyUrl and AssemblyCompanyEmail working, just add these two classes to your solution:

<AttributeUsage(AttributeTargets.Assembly)> _
Public Class AssemblyCompanyEmailAttribute
    Inherits System.Attribute

    Private _strCompanyEmail As String

    Public Sub New(ByVal email As String)
        _strCompanyEmail = email
    End Sub

    Public Overridable ReadOnly Property CompanyEmail() As String
        Get
            Return _strCompanyEmail
        End Get
    End Property
End Class

<AttributeUsage(AttributeTargets.Assembly)> _
Public Class AssemblyCompanyUrlAttribute
    Inherits System.Attribute

    Private _strCompanyUrl As String

    Public Sub New(ByVal url As String)
        _strCompanyUrl = url
    End Sub

    Public Overridable ReadOnly Property CompanyUrl() As String
        Get
            Return _strCompanyUrl
        End Get
    End Property
End Class

Once you've compiled your assembly, the obvious question is, how do we get these attributes (custom or standard) back out? I do it with a reflection loop into a NameValueCollection:

Private Shared Function GetAssemblyAttribs(ByVal a As Reflection.Assembly) _
  As Specialized.NameValueCollection

Dim attribs() As Object
Dim attrib As Object
Dim Name As String
Dim Value As String
Dim nvc As New Specialized.NameValueCollection

attribs = a.GetCustomAttributes(False)
For Each attrib In attribs
  Name = attrib.GetType().ToString()
  Value = ""
  Select Case Name
    Case "System.Reflection.AssemblyTrademarkAttribute"
      Name = "Trademark"
      Value = CType(attrib, AssemblyTrademarkAttribute).Trademark.ToString
    Case "System.Reflection.AssemblyProductAttribute"
      Name = "Product"
      Value = CType(attrib, AssemblyProductAttribute).Product.ToString
    Case "System.Reflection.AssemblyCopyrightAttribute"
      Name = "Copyright"
      Value = CType(attrib, AssemblyCopyrightAttribute).Copyright.ToString
    Case "System.Reflection.AssemblyCompanyAttribute"
      Name = "Company"
      Value = CType(attrib, AssemblyCompanyAttribute).Company.ToString
    Case "System.Reflection.AssemblyTitleAttribute"
      Name = "Title"
      Value = CType(attrib, AssemblyTitleAttribute).Title.ToString
    Case "System.Reflection.AssemblyDescriptionAttribute"
      Name = "Description"
      Value = CType(attrib, AssemblyDescriptionAttribute).Description.ToString
    Case Else
      'Console.WriteLine(Name)
  End Select
  If Value <> "" Then
    If nvc.Item(Name) = "" Then
      nvc.Add(Name, Value)
    End If
  End If
Next

Return nvc
End Function

But I am sure there are other ways.