C# 4 and .NET 4

348 ❘ ChaPTer 14 reflectiOn
Notice that the first thing you do in this method is check whether the Type reference you have been passed
actually represents a class. Because, to keep things simple, you have specified that the LastModified
attribute can be applied only to classes or member methods — you would be wasting your time by doing any
processing if the item is not a class (it could be a class, delegate, or enum).
Next, you use the Attribute.GetCustomAttributes() method to find out if this class has any
LastModifiedAttribute instances attached to it. If it does, you add their details to the output text, using a
helper method, WriteAttributeInfo().
Finally, you use the Type.GetMethods() method to iterate through all the member methods of this
data type, and then do the same with each method as you did for the class — check if it has any
LastModifiedAttribute instances attached to it and, if so, display them using WriteAttributeInfo().
The next bit of code shows the WriteAttributeInfo() method, which is responsible for working out
what text to display for a given LastModifiedAttribute instance. Note that this method is passed an
Attribute reference, so it needs to cast this to a LastModifiedAttribute reference first. After it has done
that, it uses the properties that you originally defined for this attribute to retrieve its parameters. It checks
that the date of the attribute is sufficiently recent before actually adding it to the text for display:
private static void WriteAttributeInfo(Attribute attrib)
{
}
LastModifiedAttribute lastModifiedAttrib =
attrib as LastModifiedAttribute;
if (lastModifiedAttrib == null)
{
return;
}
// check that date is in range
DateTime modifiedDate = lastModifiedAttrib.DateModified;
if (modifiedDate < backDateTo)
{
return;
}
AddToMessage(" MODIFIED: " +
modifiedDate.ToLongDateString() + ":");
AddToMessage(" " + lastModifiedAttrib.Changes);
if (lastModifiedAttrib.Issues != null)
{
AddToMessage(" Outstanding issues:" +
lastModifiedAttrib.Issues);
}
Finally, here is the helper AddToMessage() method:
}
}
static void AddToMessage(string message)
{
outputText.Append("\n" + message);
}
Running this code produces the results shown in Figure 14-2.
www.it-ebooks.info