BuildableExpressions enables CLR type generation at runtime from C# source-code strings or Expression Trees.

To install from NuGet, use:

PM> Install-Package AgileObjects.BuildableExpressions -Pre

Examples

These simple examples create a Greeter type which implements the following IGreeter interface:

namespace Greetings
{
    public interface IGreeter
    {
        string Greet();
    }
}

String -> SourceCode -> Type

To create the HelloWorldGreeter SourceCodeExpression and Type from a C# source-code string, use:

// Define a C# source-code string:
const string sourceCodeCSharp = @"
using Greetings;

public class HelloWorldGreeter : IGreeter
{
    public string Greet()
    {
        return ""Hello world!"";
    }
}";

// Create a SourceCodeExpression from the source-code string:
var sourceCode = BuildableExpression.SourceCode(sourceCodeCSharp);

// Compile the SourceCodeExpression to its CLR Types -
// pass the IGreeter type's Assembly to enable compilation:
var greeterType = sourceCode
    .CompileToTypesOrThrow(
        referenceAssemblies: typeof(IGreeter).Assembly)
    .First();

// Create an instance of the HelloWorldGreeter as an IGreeter:
var helloWorldGreeter = 
    (IGreeter)Activator.CreateInstance(greeterType);

// Call .Greet() - prints 'Hello world!':
Console.WriteLine(helloWorldGreeter.Greet());

Expression -> SourceCode -> Type

To create the HelloWorldGreeter SourceCodeExpression and Type from an Expression, use:

// Build a SourceCodeExpression using the API:
var sourceCode = BuildableExpression.SourceCode(sc =>
{
    // Define the HelloWorldGreeter class:
    sc.AddClass("HelloWorldGreeter", cls =>
    {
        // Implement the IGreeter interface:
        cls.SetImplements<IGreeter>(impl =>
        {
            // Implement the .Greet() method:
            impl.AddMethod(
                nameof(IGreeter.Greet),
                body: Expression.Constant("Hello world!"));
        });
    });
});

// Compile the SourceCodeExpression to its CLR Types -
// unlike the String -> SourceCodeExpression example, 
// reference Assemblies are not required:
var greeterType = sourceCode.CompileToTypesOrThrow().First();

// Create an instance of the HelloWorldGreeter as an IGreeter:
var helloWorldGreeter = 
    (IGreeter)Activator.CreateInstance(greeterType);

// Call .Greet() - prints 'Hello world!':
Console.WriteLine(helloWorldGreeter.Greet());

More on the SourceCodeExpression API can be found here.