HOWTO

• Open a module and print its public types
• Check if a type has a certain custom attribute
• Insert an IL instruction before another

Open a module and browse its top level types

public void PrintTypes (string fileName)
{
    ModuleDefinition module = ModuleDefinition.ReadModule (fileName);
    foreach (TypeDefinition type in module.Types) {
        if (!type.IsPublic)
            continue;

        Console.WriteLine (type.FullName);
    }
}

Check if a type has a certain custom attribute

public static bool TryGetCustomAttribute (TypeDefinition type,
    string attributeType, out CustomAttribute result)
{
    result = null;
    if (!type.HasCustomAttributes)
        return false;

    foreach (CustomAttribute attribute in type.CustomAttributes) {
        if (attribute.AttributeType.FullName != attributeType)
            continue;

        result = attribute;
        return true;
    }

    return false;
}

For a type defined as:

[Foo.Ignore ("Not working yet")]
public class Fixture {
}

Usage:

public static string GetIgnoreReason (TypeDefinition type)
{
    CustomAttribute ignoreAttribute;
    if (!TryGetCustomAttribute (type, "Foo.IgnoreAttribute", out ignoreAttribute))
        return string.Empty;

   if (ignoreAttribute.ConstructorArguments.Count != 1)
        return string.Empty;

    return (string) ignoreAttribute.ConstructorArguments [0].Value;
}

Insert an IL instruction before another

This will insert a call to a method reference as the first instruction in a method body:

var processor = method.Body.GetILProcessor();
var newInstruction = processor.Create(OpCodes.Call, someMethodReference);
var firstInstruction = method.Body.Instructions[0];
		
processor.InsertBefore(firstInstruction, newInstruction);