[Mono-dev] A possible implementation for AssemblyName.ReferenceMatchesDefinition
mlgo
mlintner at sinenomine.net
Wed Aug 28 11:30:52 UTC 2013
Thanks, I had seen that link already. How would I find Entity Framework developers?
It looks like EF is using it to while iterating through the cache to select the assembly which matches the assemblyname being passed in. The function it is used in is
DefaultAssemblyResolver.ResolveAssembly and they use it as follows:
// look in the already loaded assemblies
foreach (var current in GetAlreadyLoadedNonSystemAssemblies())
{
if (AssemblyName.ReferenceMatchesDefinition(referenceName, new AssemblyName(current.FullName)))
{
return current;
}
}
I had been looking at that link but it contradicts even the MSDN description. It seems obvious that without logic to take version into account the version it cannot resolve a correct from incorrect dll.
http://stackoverflow.com/questions/2494421/how-does-assemblyname-referencematchesdefinition-work
I was digging around on that link Somewhere on that page there is a response by some other Microsoft developers, which give an explanation of the compare which at least would be able to tell one dll from another in a meaning full way which lead me to change the implementation to the following:
public static bool ReferenceMatchesDefinition (AssemblyName reference,
AssemblyName definition)
{
if (reference == null)
throw new ArgumentNullException ("reference");
if (definition == null)
throw new ArgumentNullException ("definition");
if (!reference.Name.Equals(definition.Name, StringComparison.InvariantCultureIgnoreCase))
{
return false;
}
// http://stackoverflow.com/questions/2494421/how-does-assemblyname-referencematchesdefinition-work
// "A ReferenceIdentity matches a DefinitionIdentity, if and only if the value of all the attributes
// specified in the ReferenceIdentity match the value of the corresponding attributes of the DefinitionIdentity.
// If an attribute is missing in the ReferenceIdentity, it matches any value for that attribute in DefinitionIdentity.
// For example, Ref “name” matches Def “name, culture=neutral”, and Def “name, culture=en-us”.
// But Ref “name, culture=neutral” does not match Def “name, culture=en-us”."
if (reference.CultureInfo != null)
{
if (definition.CultureInfo == null || reference.CultureInfo != definition.CultureInfo )
{
return false;
}
}.
byte [] refToken = reference.GetPublicKeyToken();
if (refToken != null && refToken.Length != 0)
{
byte [] defToken = definition.GetPublicKeyToken();
if (deftoken == null || defToken.Length != 4 ||
refToken[0] != defToken[0] || refToken[1] != defToken[1] ||
refToken[2] != defToken[2] || refToken[3] != defToken[3] )
{
return false;
}
if (reference.Version != null)
{
if (definition.Version == null || reference.Version != definition.Version )
{
return false;
}
}
}
return true ;
}
Don't know how Im going to find entity Framework developers. I always will write Unit Tests of course.
________________________________
From: Marek Safar-2 [via Mono] [ml-node+s1490590n4660696h61 at n4.nabble.com]
Sent: Wednesday, August 28, 2013 2:21 AM
To: Mark Lintner
Subject: Re: A possible implementation for AssemblyName.ReferenceMatchesDefinition
Hi,
This API is broken by design and it's not clear what it should really do. It'd probably be better to check with EF devs whether they really intended to use it and for what purposes. Even for naive implementation please write unit test and check whether it passes on .net
http://stackoverflow.com/questions/2494421/how-does-assemblyname-referencematchesdefinition-work
Marek
On Tue, Aug 27, 2013 at 5:29 PM, mlgo <[hidden email]<https://connect.emailsrvr.com/owa/UrlBlockedError.aspx>> wrote:
According to
http://msdn.microsoft.com/en-us/library/system.reflection.assemblyname.referencematchesdefinition.aspx
The following is what is expected to be returned from
ReferenceMatchesDefinition.
Returns a value indicating whether two assembly names are the same. The
comparison is based on the simple assembly names.
This seems naïve but below is a tentative implementation of that. Any ideas?
public static bool ReferenceMatchesDefinition (AssemblyName reference,
AssemblyName definition)
{
if (reference == null)
throw new ArgumentNullException ("reference");
if (definition == null)
throw new ArgumentNullException ("definition");
if (reference.Name != definition.Name)
return false;
return reference.Name.Equals(definition.Name);
}
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