C# – How to load an older version of a .NET assembly

cnet

I have a WPF/C# application that references .NET 4.0 assemblies. However, within the application is a text editor that needs to display C# intellisense tied to .NET 3.5 assemblies. Thus, I want to be able to load the appropriate .NET 3.5 assemblies at runtime. However, when I try to use:

Assembly.Load()
Assembly.LoadFile()
Assembly.LoadFrom()

I always get the latest version from the GAC. Reading their MSDN pages, it seems like that's unfortunately by design.

I tried following the proposed solutions in this stack overflow post. However, the linked webpages' solutions don't work and a remoting process seems like overkill. Does anyone know a better and/or easier way to load older .NET assemblies at runtime?

Best Answer

By default, you cannot load assemblies made for previous versions of the .NET framework on the .NET framework version 4.

However, there is a configuration attribute that allows that: http://msdn.microsoft.com/en-us/library/bbx34a2h.aspx

Put the following lines in your app.config file:

<configuration>
    <startup useLegacyV2RuntimeActivationPolicy="true|false" > 
    </startup>
</configuration>

There are reasons why this is not active by default, but I believe that it should be appropriate for your use.

Related Solutions

C# – How to cast int to enum

From an int:

YourEnum foo = (YourEnum)yourInt;

From a string:

YourEnum foo = (YourEnum) Enum.Parse(typeof(YourEnum), yourString);

// The foo.ToString().Contains(",") check is necessary for enumerations marked with an [Flags] attribute
if (!Enum.IsDefined(typeof(YourEnum), foo) && !foo.ToString().Contains(","))
{
    throw new InvalidOperationException($"{yourString} is not an underlying value of the YourEnum enumeration.")
}

Update:

From number you can also

YourEnum foo = (YourEnum)Enum.ToObject(typeof(YourEnum) , yourInt);

C# – How to get the path of the assembly the code is in

I've defined the following property as we use this often in unit testing.

public static string AssemblyDirectory
{
    get
    {
        string codeBase = Assembly.GetExecutingAssembly().CodeBase;
        UriBuilder uri = new UriBuilder(codeBase);
        string path = Uri.UnescapeDataString(uri.Path);
        return Path.GetDirectoryName(path);
    }
}

The Assembly.Location property sometimes gives you some funny results when using NUnit (where assemblies run from a temporary folder), so I prefer to use CodeBase which gives you the path in URI format, then UriBuild.UnescapeDataString removes the File:// at the beginning, and GetDirectoryName changes it to the normal windows format.

Best Answer

Related Solutions

C# – How to cast int to enum

C# – How to get the path of the assembly the code is in

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