Question

I’m trying to figure out if it’s possible when you are dynamically generating assemblies, to reference a type in a previously dynamically generated assembly.

For example:

using System;
using System.CodeDom.Compiler;
using System.Reflection;
using Microsoft.CSharp;

CodeDomProvider provider = new CSharpCodeProvider();
CompilerParameters parameters = new CompilerParameters();

parameters.GenerateInMemory = true;

CompilerResults results = provider.CompileAssemblyFromSource(parameters, @"
namespace Dynamic
{
    public class A
    {
    }
}
");

Assembly assem = results.CompiledAssembly;

CodeDomProvider provider2 = new CSharpCodeProvider();
CompilerParameters parameters2 = new CompilerParameters();

parameters2.ReferencedAssemblies.Add(assem.FullName);
parameters2.GenerateInMemory = true;

CompilerResults results2 = provider2.CompileAssemblyFromSource(parameters2, @"
namespace Dynamic
{
    public class B : A
    {
    }
}
");

if (results2.Errors.HasErrors)
{
    foreach (CompilerError error in results2.Errors)
    {
        Console.WriteLine(error.ErrorText);
    }
}
else
{
    Assembly assem2 = results2.CompiledAssembly;
}

This code prints the following on the console: The type or namespace name 'A' could not be found (are you missing a using directive or an assembly reference?)

I’ve tried it lots of different ways, but nothing seems to be working. Am I missing something? Is this even possible?

EDIT: Fixing the bug in the code provides this error instead:
Metadata file 'l0livsmn, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null' could not be found

EDIT2: Bit of a side note, but changing GenerateInMemory to false, and doing parameters2.ReferencedAssemblies.Add(assem.Location); will cause it to compile correctly, but I’d greatly prefer to reference the assembly that is directly in memory rather than outputting temporary files.

Answer 1

I think that in

CompilerResults results2 = provider2.CompileAssemblyFromSource(parameters, @"
namespace Dynamic
{
    public class B : A
    {
    }
}
");

You want to pass parameters2, not parameters.

I found the way to do it, you need NOT to compile the first one in memory, if you don’t do that, it will create a dll for this assembly in your temp directory, plus, in your call to

ReferencedAssemblies.Add() 

you dont pass the assembly name, you pass the assembly path, take a look at this code, it should work flawlessly :

        CodeDomProvider provider = new CSharpCodeProvider();
        CompilerParameters parameters = new CompilerParameters();            

        CompilerResults results = provider.CompileAssemblyFromSource(parameters, @"
            namespace Dynamic
            {
                public class A
                {
                }
            }
            ");

        Assembly assem = results.CompiledAssembly;

        CodeDomProvider provider2 = new CSharpCodeProvider();
        CompilerParameters parameters2 = new CompilerParameters();

        parameters2.ReferencedAssemblies.Add(assem.Location);
        parameters2.GenerateInMemory = true;

        CompilerResults results2 = provider2.CompileAssemblyFromSource(parameters2, @"
            namespace Dynamic
            {
                public class B : A
                {
                }
            }
            ");

        if (results2.Errors.HasErrors)
        {
            foreach (CompilerError error in results2.Errors)
            {
                Console.WriteLine(error.ErrorText);
            }
        }
        else
        {
            Assembly assem2 = results2.CompiledAssembly;
        }