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Dynamiclly loaded assemblies and IsDefined
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Patrik Löwendahl [C# MVP] (VIP)
Hi,

I'm running laps around this, need some fresh input.

I'm writing a component that runs in asp.net 1.1 (no sp) which dynamically
loads assemblies from a shared store. Each of theese assemblies contains one
or types marked with a custom attribute. When iterating and checking theese
types IsDefined won't return true even for types where the attribute is
present.

Retrieving the attributes and manually iterating them will show that the
attribute truely is present, but no luck with IsDefined.

Where's my head at??

<code>
// ExportDescriptionAttribute is a standard custom attribute, with Attribute
target set to class.
// there's no inheritance issues either.
string path = HttpContext.Current.Server.MapPath("bin/admin.export.dll");
Assembly expAss = Assembly.LoadFile(path);
foreach(Type exportType in expAss.GetTypes()) {
if(exportType.IsDefined(typeof(ExportDescriptionAttribute), false)){
}
}
</code>

--
Patrik Löwendahl [C# MVP]
www.cshrp.net - "Elegant code by witty programmers"
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Robert Jordan
Patrik Löwendahl [C# MVP] wrote:

[Original message clipped]

I encountered the same problem a couple of months ago (.NET 1.1).
Thought it was my bug, I've rewritten the code using
GetCustomAttributes.

bye
Rob
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Richard Blewett
So you are saying that if you use
GetCustomAttributes(typeof(ExportDescriptionAttribute), false); you get a
collection of the attributes back OK?

Regards

Richard Blewett - DevelopMentor
http://staff.develop.com/richardb/weblog

"Patrik Löwendahl [C# MVP]" <Click here to reveal e-mail address> wrote in
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[Original message clipped]
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Patrik Löwendahl [C# MVP] (VIP)
No, asking for the type don't do it,

But doing a foreach(object attr in t.GetCustomAttributes(true))

will let me find it manually.

--
Patrik Löwendahl [C# MVP]
www.cshrp.net - "Elegant code by witty programmers"

"Richard Blewett" <Click here to reveal e-mail address> wrote in message
news:Click here to reveal e-mail address...
[Original message clipped]
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Richard Blewett [DevelopMentor] (VIP)
Are you sure that the assemblies you are loading weren't built against a
version of the attribute assembly other than the one you are testing for?

The runtime considers the same type from two different versions of an
assembly to be two distinct types and so would cause the behaviour you are
seeing.

Regards

Richard Blewett - DevelopMentor
http://staff.develop.com/richardb/weblog

"Patrik Löwendahl [C# MVP]" wrote:

[Original message clipped]
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System.Reflection.Assembly
System.Web.HttpContext




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