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Find out the letter of the USB [duplicate]

How do I find the application's path in a console application?
In Windows Forms, I can use Application.StartupPath to find the current path, but this doesn't seem to be available in a console application.

System.Reflection.Assembly.GetExecutingAssembly().Location1
Combine that with System.IO.Path.GetDirectoryName if all you want is the directory.
1As per Mr.Mindor's comment:
System.Reflection.Assembly.GetExecutingAssembly().Location returns where the executing assembly is currently located, which may or may not be where the assembly is located when not executing. In the case of shadow copying assemblies, you will get a path in a temp directory. System.Reflection.Assembly.GetExecutingAssembly().CodeBase will return the 'permanent' path of the assembly.

You can use the following code to get the current application directory.
AppDomain.CurrentDomain.BaseDirectory

You have two options for finding the directory of the application, which you choose will depend on your purpose.
// to get the location the assembly is executing from
//(not necessarily where the it normally resides on disk)
// in the case of the using shadow copies, for instance in NUnit tests,
// this will be in a temp directory.
string path = System.Reflection.Assembly.GetExecutingAssembly().Location;
//To get the location the assembly normally resides on disk or the install directory
string path = System.Reflection.Assembly.GetExecutingAssembly().CodeBase;
//once you have the path you get the directory with:
var directory = System.IO.Path.GetDirectoryName(path);

Probably a bit late but this is worth a mention:
Environment.GetCommandLineArgs()[0];
Or more correctly to get just the directory path:
System.IO.Path.GetDirectoryName(Environment.GetCommandLineArgs()[0]);
Edit:
Quite a few people have pointed out that GetCommandLineArgs is not guaranteed to return the program name. See The first word on the command line is the program name only by convention. The article does state that "Although extremely few Windows programs use this quirk (I am not aware of any myself)". So it is possible to 'spoof' GetCommandLineArgs, but we are talking about a console application. Console apps are usually quick and dirty. So this fits in with my KISS philosophy.
Edit
It seems, from feedback, that most of the other solutions don't work when you are using a unit testing system. This sort of makes sense as the executable item is not your application but the testing system. I have not checked this out - so I could be completely wrong. If this is so, I will delete this edit.

For anyone interested in asp.net web apps. Here are my results of 3 different methods
protected void Application_Start(object sender, EventArgs e)
{
string p1 = System.IO.Path.GetDirectoryName(System.Reflection.Assembly.GetExecutingAssembly().Location);
string p2 = System.Web.Hosting.HostingEnvironment.ApplicationPhysicalPath;
string p3 = this.Server.MapPath("");
Console.WriteLine("p1 = " + p1);
Console.WriteLine("p2 = " + p2);
Console.WriteLine("p3 = " + p3);
}
result
p1 = C:\Windows\Microsoft.NET\Framework64\v4.0.30319\Temporary ASP.NET Files\root\a897dd66\ec73ff95\assembly\dl3\ff65202d\29daade3_5e84cc01
p2 = C:\inetpub\SBSPortal_staging\
p3 = C:\inetpub\SBSPortal_staging
the app is physically running from "C:\inetpub\SBSPortal_staging", so the first solution is definitely not appropriate for web apps.

The answer above was 90% of what I needed, but returned a Uri instead of a regular path for me.
As explained in the MSDN forums post, How to convert URI path to normal filepath?, I used the following:
// Get normal filepath of this assembly's permanent directory
var path = new Uri(
System.IO.Path.GetDirectoryName(
System.Reflection.Assembly.GetExecutingAssembly().CodeBase)
).LocalPath;

If you are looking for a .NET Core compatible way, use
System.AppContext.BaseDirectory
This was introduced in .NET Framework 4.6 and .NET Core 1.0 (and .NET Standard 1.3). See: AppContext.BaseDirectory Property.
According to this page,
This is the prefered replacement for AppDomain.CurrentDomain.BaseDirectory in .NET Core

You may be looking to do this:
System.IO.Path.GetDirectoryName(
System.Reflection.Assembly.GetExecutingAssembly().GetName().CodeBase)

you can use this one instead.
System.Environment.CurrentDirectory

For Console Applications, you can try this:
System.IO.Directory.GetCurrentDirectory();
Output (on my local machine):
c:\users\xxxxxxx\documents\visual studio 2012\Projects\ImageHandler\GetDir\bin\Debug
Or you can try (there's an additional backslash in the end):
AppDomain.CurrentDomain.BaseDirectory
Output:
c:\users\xxxxxxx\documents\visual studio 2012\Projects\ImageHandler\GetDir\bin\Debug\

I have used this code and get the solution.
AppDomain.CurrentDomain.BaseDirectory

Following line will give you an application path:
var applicationPath = Path.GetDirectoryName(Process.GetCurrentProcess().MainModule.FileName)
Above solution is working properly in the following situations:
simple app
in another domain where Assembly.GetEntryAssembly() would return null
DLL is loaded from Embedded resources as a byte array and loaded to AppDomain as Assembly.Load(byteArrayOfEmbeddedDll)
with Mono's mkbundle bundles (no other methods work)

You can simply add to your project references System.Windows.Forms and then use the System.Windows.Forms.Application.StartupPath as usual .
So, not need for more complicated methods or using the reflection.

I have used
System.AppDomain.CurrentDomain.BaseDirectory
when I want to find a path relative to an applications folder. This works for both ASP.Net and winform applications. It also does not require any reference to System.Web assemblies.

I mean, why not a p/invoke method?
using System;
using System.IO;
using System.Runtime.InteropServices;
using System.Text;
public class AppInfo
{
[DllImport("kernel32.dll", CharSet = CharSet.Auto, ExactSpelling = false)]
private static extern int GetModuleFileName(HandleRef hModule, StringBuilder buffer, int length);
private static HandleRef NullHandleRef = new HandleRef(null, IntPtr.Zero);
public static string StartupPath
{
get
{
StringBuilder stringBuilder = new StringBuilder(260);
GetModuleFileName(NullHandleRef, stringBuilder, stringBuilder.Capacity);
return Path.GetDirectoryName(stringBuilder.ToString());
}
}
}
You would use it just like the Application.StartupPath:
Console.WriteLine("The path to this executable is: " + AppInfo.StartupPath + "\\" + System.Diagnostics.Process.GetCurrentProcess().ProcessName + ".exe");

Assembly.GetEntryAssembly().Location or Assembly.GetExecutingAssembly().Location
Use in combination with System.IO.Path.GetDirectoryName() to get only the directory.
The paths from GetEntryAssembly() and GetExecutingAssembly() can be different, even though for most cases the directory will be the same.
With GetEntryAssembly() you have to be aware that this can return null if the entry module is unmanaged (ie C++ or VB6 executable). In those cases it is possible to use GetModuleFileName from the Win32 API:
[DllImport("kernel32.dll", CharSet = CharSet.Auto)]
public static extern int GetModuleFileName(HandleRef hModule, StringBuilder buffer, int length);

I use this if the exe is supposed to be called by double clicking it
var thisPath = System.IO.Directory.GetCurrentDirectory();

in VB.net
My.Application.Info.DirectoryPath
works for me (Application Type: Class Library). Not sure about C#...
Returns the path w/o Filename as string

I didn't see anyone convert the LocalPath provided by .Net Core reflection into a usable System.IO path so here's my version.
public static string GetApplicationRoot()
{
var exePath = new Uri(System.Reflection.
Assembly.GetExecutingAssembly().CodeBase).LocalPath;
return new FileInfo(exePath).DirectoryName;
}
This will return the full C:\\xxx\\xxx formatted path to where your code is.

AppDomain.CurrentDomain.BaseDirectory
Will resolve the issue to refer the 3rd party reference files with installation packages.

With .NET Core 3 and above you will get the .dll and not the .exe file. To get the .exe file path you can use.
var appExePath = Process.GetCurrentProcess().MainModule.FileName;

Try this simple line of code:
string exePath = Path.GetDirectoryName( Application.ExecutablePath);

For .NET 6 there's Environment.ProcessPath.
See https://learn.microsoft.com/en-us/dotnet/api/system.environment.processpath?view=net-6.0

None of these methods work in special cases like using a symbolic link to the exe, they will return the location of the link not the actual exe.
So can use QueryFullProcessImageName to get around that:
using System;
using System.IO;
using System.Runtime.InteropServices;
using System.Text;
using System.Diagnostics;
internal static class NativeMethods
{
[DllImport("kernel32.dll", SetLastError = true)]
internal static extern bool QueryFullProcessImageName([In]IntPtr hProcess, [In]int dwFlags, [Out]StringBuilder lpExeName, ref int lpdwSize);
[DllImport("kernel32.dll", SetLastError = true)]
internal static extern IntPtr OpenProcess(
UInt32 dwDesiredAccess,
[MarshalAs(UnmanagedType.Bool)]
Boolean bInheritHandle,
Int32 dwProcessId
);
}
public static class utils
{
private const UInt32 PROCESS_QUERY_INFORMATION = 0x400;
private const UInt32 PROCESS_VM_READ = 0x010;
public static string getfolder()
{
Int32 pid = Process.GetCurrentProcess().Id;
int capacity = 2000;
StringBuilder sb = new StringBuilder(capacity);
IntPtr proc;
if ((proc = NativeMethods.OpenProcess(PROCESS_QUERY_INFORMATION | PROCESS_VM_READ, false, pid)) == IntPtr.Zero)
return "";
NativeMethods.QueryFullProcessImageName(proc, 0, sb, ref capacity);
string fullPath = sb.ToString(0, capacity);
return Path.GetDirectoryName(fullPath) + #"\";
}
}

Path.GetDirectoryName(System.Diagnostics.Process.GetCurrentProcess().MainModule.FileName)
Is the only one that has worked for me in every case I have tried.

In .NET 6, my WPF app (<TargetFramework>net6.0-windows</TargetFramework>) returns the .dll file path for Assembly.GetEntryAssembly()!.Location instead of the .exe file. They introduced System.Environment.ProcessPath for this purpose:
var path = Environment.ProcessPath; // Note it may be null
Returns the path of the executable that started the currently executing process. Returns null when the path is not available.
See discussion for it here and here.

I use this for console + net 6
Path.GetDirectoryName(System.Reflection.Assembly.GetExecutingAssembly().Location)

The techniques, and pitfalls, keep changing. The below assumes you're running a .NET 6 console app on linux (on win/mac the results will follow a similar pattern, just replace /usr/share/ and /home/username/ with the standard locations for your OS).
Demo:
Console.WriteLine("Path.GetDirectoryName(Process.GetCurrentProcess()?.MainModule?.FileName) = " + Path.GetDirectoryName(Process.GetCurrentProcess()?.MainModule?.FileName));
Console.WriteLine("Path.GetDirectoryName(Environment.ProcessPath) = " + Path.GetDirectoryName(Environment.ProcessPath));
Console.WriteLine("Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location) = " + Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location));
Console.WriteLine("typeof(SomeType).Assembly.Location = " + typeof(SomeType).Assembly.Location);
Console.WriteLine("Path.GetDirectoryName(Environment.GetCommandLineArgs()[0]) = " + Path.GetDirectoryName(Environment.GetCommandLineArgs()[0]));
Console.WriteLine("AppDomain.CurrentDomain.BaseDirectory = " + AppDomain.CurrentDomain.BaseDirectory);
Console.WriteLine("System.AppContext.BaseDirectory = " + System.AppContext.BaseDirectory);
Results:
Path.GetDirectoryName(Process.GetCurrentProcess()?.MainModule?.FileName) = /usr/share/dotnet
Path.GetDirectoryName(Environment.ProcessPath) = /usr/share/dotnet
Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location) = /home/username/myproject/bin/Debug/net6.0
typeof(SomeType).Assembly.Location = /home/username/myproject/bin/Debug/net6.0
Path.GetDirectoryName(Environment.GetCommandLineArgs()[0]) = /home/username/myproject/bin/Debug/net6.0
AppDomain.CurrentDomain.BaseDirectory = /home/username/myproject/bin/Debug/net6.0/
System.AppContext.BaseDirectory = /home/username/myproject/bin/Debug/net6.0/
Each approach has its own pros and cons - see the other answers to learn in which uses cases to use which approach.
I run my .NET 6 console app with dotnet myapp, so what works (reliably) for me is either of:
typeof(SomeType).Assembly.Location
// or
Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location)

Here is a reliable solution that works with 32bit and 64bit applications.
Add these references:
using System.Diagnostics;
using System.Management;
Add this method to your project:
public static string GetProcessPath(int processId)
{
string MethodResult = "";
try
{
string Query = "SELECT ExecutablePath FROM Win32_Process WHERE ProcessId = " + processId;
using (ManagementObjectSearcher mos = new ManagementObjectSearcher(Query))
{
using (ManagementObjectCollection moc = mos.Get())
{
string ExecutablePath = (from mo in moc.Cast<ManagementObject>() select mo["ExecutablePath"]).First().ToString();
MethodResult = ExecutablePath;
}
}
}
catch //(Exception ex)
{
//ex.HandleException();
}
return MethodResult;
}
Now use it like so:
int RootProcessId = Process.GetCurrentProcess().Id;
GetProcessPath(RootProcessId);
Notice that if you know the id of the process, then this method will return the corresponding ExecutePath.
Extra, for those interested:
Process.GetProcesses()
...will give you an array of all the currently running processes, and...
Process.GetCurrentProcess()
...will give you the current process, along with their information e.g. Id, etc. and also limited control e.g. Kill, etc.*

You can create a folder name as Resources within the project using Solution Explorer,then you can paste a file within the Resources.
private void Form1_Load(object sender, EventArgs e) {
string appName = Environment.CurrentDirectory;
int l = appName.Length;
int h = appName.LastIndexOf("bin");
string ll = appName.Remove(h);
string g = ll + "Resources\\sample.txt";
System.Diagnostics.Process.Start(g);
}

C# Generating dynamic executable from project

I wanna generate an exe file with some changes in code from another C# exe.
I know that can easy compile .cs single class using CodeDom.Compiler
The thing I want to know is how to compile a project with 'Resources', 'Settings', 'Forms' and other elements.
CSharpCodeProvider.CompileAssemblyFromSource(CompilerParameters, sources[]);
So, the question is where can I add all resources, settings and form (.resx)?
And can I do it with byte[] streams. Without unpacking project's zip.
Sorry for bad English and mby stupid questions. I wish somebody will help me...
For Example: I have byte[] array of resource file 'pic.png' and I wanna attach it to compiled exe as embedded resource.

You should learn about the new compiler service provided by Microsoft in Microsoft.CodeAnalysis code name "Roslyn".
Roslyn provides you the way to compile the code and everything on the fly including creating and compiling complete solution and projects in-memory.
I think what you're looking for can be achieved via Roslyn. See below sample:
class Program
{
static void Main()
{
var syntaxTree = SyntaxTree.ParseCompilationUnit(
#"using System;
using System.Resources;
namespace ResSample
{
class Program
{
static void Main()
{
ResourceManager resMan = new ResourceManager(""ResSample.Res1"", typeof(Program).Assembly);
Console.WriteLine(resMan.GetString(""String1""));
}
}
}");
var comp = Compilation.Create("ResTest.exe")
.AddReferences(new AssemblyNameReference("mscorlib"))
.AddSyntaxTrees(syntaxTree);
var resourcePath = "ResSample.Res1.resources"; //Provide full path to resource file here
var resourceDescription = new ResourceDescription(
resourceName: "ResSample.Res1.resources",
dataProvider: () => File.OpenRead(resourcePath),
isPublic: false);
var emitResult = comp.Emit(
executableStream: File.Create("ResTest.exe"),
manifestResources: new[] { resourceDescription });
Debug.Assert(emitResult.Success);
}
Original Source here
At line dataProvider: () => File.OpenRead(resourcePath), you can provide your own 'FileStream' like () => return _myResourceStream) for your resource file.

BundleTransformer.Less inject variables depending on context/request

We would like the use the bundling mechanism of System.Web.Optimization in combination with the Less transformer.
The problem is that the same application/server serves pages for different branded websites. So depending on the 'SiteContext' the same .less files are used but different values should be used by the .less variables. So we want the (re)use the same less files but with different variables depending on the context of the request.
I tried a couple of different theories:
In all 3 cases I setup different bundles depending on the SiteContext.
1 inject an #import directive with the themed variables by using a custom VirtualPathProvider that intercepts the variables.less file.
So I have:
the styling file eg: header.less (imports the variables file)
the variables file: variables.less
a themed variables file: variables-theme.less (injected in variables.less via the VirtualPathProvider)
This is not working because the BundleTransformer cache sees this as the same file and doesn't know about the SiteContext. The cache key is based on the Url of the IAsset and we cannot influence this behavior.
2 Replace the variables.less import by variables-themed.less with an custom transformer that runs before the Less transformer.
Again no luck, same caching issues.
And as a side effect, the extra transformer was not called in debug because the assets are not bundled but called individually by the LessAssetHandler. This could be solved by writing your own AssetHandler that calls all required transformers.
3 create themed Asset names that are resolved by a custom VirtualPathProvider
Eg. Add header-themeX.less to the bundle, this file doesn't exist but you resolve this file to header.less and use method 2 to set the correct variables file import. (replace the import of the variables.less to the themed version).
Once again no luck. I think this could solve the caching issue if it wasn't for the Bundle.Include(string virtualPath) that does a File.Exists(path) internally. It doesn't pass via the CustomVirtualPathProvider.
Am I looking to deep to solve this?
All ideas are welcome, I can imagine that this will become a problem to more and more people as the System.Web.Optimization library gets more popular...
Keep in mind that:
we have a lot of .less/css files
we will have 5 or so themes
we like to keep things working in visual studio (that is why header.less has a ref. to variables.less)
Thanks for any feedback.

Michael!
You use the Microsoft ASP.NET Web Optimization Framework and the Bundle Transformer in multi-tenant environment, so you need to replace some components of the System.Web.Optimization and create own versions of the debugging HTTP-handlers (see «Problem: LESS file imports are added to BundleResponse.Files collection» discussion). As far as I know, Murat Cakir solve all these problems in the SmartStore.NET project.
In the Bundle Transformer there are 2 ways to inject of LESS-variables:
Look a properties GlobalVariables and ModifyVariables of LESS-translator:
using System.Collections.Generic;
using System.Web.Optimization;
using BundleTransformer.Core.Builders;
using BundleTransformer.Core.Orderers;
using BundleTransformer.Core.Transformers;
using BundleTransformer.Core.Translators;
using BundleTransformer.Less.Translators;
public class BundleConfig
{
public static void RegisterBundles(BundleCollection bundles)
{
var nullBuilder = new NullBuilder();
var nullOrderer = new NullOrderer();
var lessTranslator = new LessTranslator
{
GlobalVariables = "my-variable='Hurrah!'",
ModifyVariables = "font-family-base='Comic Sans MS';body-bg=lime;font-size-h1=50px"
};
var cssTransformer = new CssTransformer(new List<ITranslator>{ lessTranslator });
var commonStylesBundle = new Bundle("~/Bundles/BootstrapStyles");
commonStylesBundle.Include(
"~/Content/less/bootstrap-3.1.1/bootstrap.less");
commonStylesBundle.Builder = nullBuilder;
commonStylesBundle.Transforms.Add(cssTransformer);
commonStylesBundle.Orderer = nullOrderer;
bundles.Add(commonStylesBundle);
}
}
Create a custom item transformation:
using System.Text;
using System.Web.Optimization;
public sealed class InjectContentItemTransform : IItemTransform
{
private readonly string _beforeContent;
private readonly string _afterContent;
public InjectContentItemTransform(string beforeContent, string afterContent)
{
_beforeContent = beforeContent ?? string.Empty;
_afterContent = afterContent ?? string.Empty;
}
public string Process(string includedVirtualPath, string input)
{
if (_beforeContent.Length == 0 && _afterContent.Length == 0)
{
return input;
}
var contentBuilder = new StringBuilder();
if (_beforeContent.Length > 0)
{
contentBuilder.AppendLine(_beforeContent);
}
contentBuilder.AppendLine(input);
if (_afterContent.Length > 0)
{
contentBuilder.AppendLine(_afterContent);
}
return contentBuilder.ToString();
}
}
And register this transformation as follows:
using System.Web.Optimization;
using BundleTransformer.Core.Orderers;
using BundleTransformer.Core.Bundles;
public class BundleConfig
{
public static void RegisterBundles(BundleCollection bundles)
{
var nullOrderer = new NullOrderer();
const string beforeLessCodeToInject = #"#my-variable: 'Hurrah!';";
const string afterLessCodeToInject = #"#font-family-base: 'Comic Sans MS';
#body-bg: lime;
#font-size-h1: 50px;";
var commonStylesBundle = new CustomStyleBundle("~/Bundles/BootstrapStyles");
commonStylesBundle.Include(
"~/Content/less/bootstrap-3.1.1/bootstrap.less",
new InjectContentItemTransform(beforeLessCodeToInject, afterLessCodeToInject));
commonStylesBundle.Orderer = nullOrderer;
bundles.Add(commonStylesBundle);
}
}
Both ways have disadvantage: the injection of LESS-variables does not work in debug mode.

Print the source filename and linenumber in C#

Is there any way to retrieve the current source filename and linenumber in C# code and print that value in the console output? Like LINE and FILE in C?
Please advise.
Many thanks

Anders Hejlsberg presented new API for that in BUILD keynote:
Print current file name, method name and line number
private static void Log(string text,
[CallerFilePath] string file = "",
[CallerMemberName] string member = "",
[CallerLineNumber] int line = 0)
{
Console.WriteLine("{0}_{1}({2}): {3}", Path.GetFileName(file), member, line, text);
}
Test:
Log(".NET rocks!");
Output:
Program.cs_Main(11): .NET rocks!
What's going on here?
You define a method with optional parameters and decorate them with special attributes. If you call method without passing actual arguments (leave defaults) - the Framework populates them for you.

This answer is outdated! See #taras' answer for more recent information.
No constant :(
What you can do is a lot uglier :
string currentFile = new System.Diagnostics.StackTrace(true).GetFrame(0).GetFileName();
int currentLine = new System.Diagnostics.StackTrace(true).GetFrame(0).GetFileLineNumber();
Works only when PDB files are available.

You can use the StackTrace object from the System.Diagnostics namespace but the information will only be available if the PDB files are there.
PDB files are generated by default for both the Debug and Release builds the only difference is that Debug is setup to generate a full debug info where as the Release build is setup to only generate a pdb (full/pdb-only).
Console.WriteLine(new StackTrace(true).GetFrame(0).GetFileName());
Console.WriteLine(new StackTrace(true).GetFrame(0).GetFileLineNumber());

There are no constants defined for that as of now.
The .NET way of doing it is using StackTrace class.
It however works only for Debug builds. So in case you use it, you can have the code using StackTrace between
#if DEBUG
//your StackTrace code here
#endif
You can read about using #if preprocessors for your DEBUG vs. RELEASE builds in the following Stackoverflow thread.
C# if/then directives for debug vs release
EDIT: Just in case you still need this debugging information in release builds, read the following answer on Stackoverflow:
Display lines number in Stack Trace for .NET assembly in Release mode

If you want some more internal detail, but you don't specifically need filename and line number, you can do something like this:
System.Diagnostics.Debug.Print(this.GetType().ToString() + " My Message");
This has an advantage over printing out the filename in that if you put this in a parent class, it will print out the child class name that is actually running the code.

If you wanted to write your own version of Debug.Assert, then here's a more complete answer:
// CC0, Public Domain
using System.Diagnostics;
using System.Runtime.CompilerServices;
using System;
public static class Logger {
[Conditional("DEBUG")]
public static void Assert(bool condition, string msg,
[CallerFilePath] string file = "",
[CallerMemberName] string member = "",
[CallerLineNumber] int line = 0
)
{
// Debug.Assert opens a msg box and Trace only appears in
// a debugger, so implement our own.
if (!condition)
{
// Roughly follow style of C# error messages:
// > ideone.cs(14,11): error CS1585: Member modifier 'static' must precede the member type and name
Console.WriteLine($"{file}({line}): assert: in {member}: {msg}");
// Or more precisely match style with a fake error so error-parsing tools will detect it:
// Console.WriteLine($"{file}({line}): warning CS0: {msg}");
}
}
}
class Program {
static void Main(string[] args) {
Logger.Assert(1+1 == 4, "Why not!");
}
}
Try it online.

Is it possible to serialize a C# code block?

I'm using C# with .NET 3.5. Is it possible to serialize a block of code, transmit it somewhere, deserialize it, and then execute it?
An example usage of this would be:
Action<object> pauxPublish = delegate(object o)
{
if (!(o is string))
{
return;
}
Console.WriteLine(o.ToString());
};
Transmitter.Send(pauxPublish);
With some remote program doing:
var action = Transmitter.Recieve();
action("hello world");
My end goal is to be able to execute arbitrary code in a different process (which has no prior knowledge of the code).

YES!!!
We have done this for a very real case of performance. Doing this at runtime or using a DSL was not an option due to performance.
We compile the code into an assembly, and rip the IL out of the method. We then get all the metadata associated with this method and serialize the whole mess via XML, compress it, and put it in our database.
At re-hydration time, we re-constitute the IL with the metadata using the DynamicMethod class, and execute it.
We do this because of speed. We have thousands of little blocks of code. Unfortunately, to compile a block of code and run it on the fly takes at least 250 ms, which is way too slow for us. We took this approach, and it is working REALLY well. At run-time, it takes an unmeasurable amount of time to reconstitute the method and run it.
Only thing to keep an eye on... Signed assemblies and Unsigned assemblies cannot mix the serialized method data.

You could try to use IronPython in your project. It's trivial to do what you are asking in Python. The Python code could call your C# methods. As for security, you could execute the code in a restricted environment of some kind (one example is RestrictedPython).

Generally speaking that sounds like a really bad idea and a big security hole.
You don't want another process to execute any code. Understand what you really need another process to do and build a little DSL around it.

You could also send it as a string then use the CodeDomProvider to compile it, same result. I have an example bit of code thus:
using System;
using System.CodeDom.Compiler;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Text;
using Microsoft.CSharp;
namespace DynamicCodeApplication
{
class azCodeCompiler
{
private List<string> assemblies;
public azCodeCompiler()
{
assemblies = new List<string>();
scanAndCacheAssemblies();
}
public Assembly BuildAssembly(string code)
{
CodeDomProvider prov = CodeDomProvider.CreateProvider("CSharp");
string[] references = new string[] { }; // Intentionally empty, using csc.rsp
CompilerParameters cp = new CompilerParameters(references)
{
GenerateExecutable = false,
GenerateInMemory = true
};
string path = System.Runtime.InteropServices.RuntimeEnvironment.GetRuntimeDirectory();
cp.CompilerOptions = "#" + path + #"\csc.rsp";
CompilerResults cr = prov.CompileAssemblyFromSource(cp, code);
foreach (CompilerError err in cr.Errors)
{
Console.WriteLine(err.ToString());
}
return cr.CompiledAssembly;
}
public object ExecuteCode(string code,
string namespacename, string classname,
string functionname, bool isstatic, params object[] args)
{
object returnval = null;
Assembly asm = BuildAssembly(code);
object instance = null;
Type type = null;
if (isstatic)
{
type = asm.GetType(namespacename + "." + classname);
}
else
{
instance = asm.CreateInstance(namespacename + "." + classname);
type = instance.GetType();
}
MethodInfo method = type.GetMethod(functionname);
returnval = method.Invoke(instance, args);
return returnval;
}
private void scanAndCacheAssemblies()
{
/*
foreach (string str in Directory.GetFiles(#"C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727"))
{
if (str.Contains(".dll"))
{
foreach (string st in str.Split(new char[] { '\\' }))
{
if (st.Contains(".dll"))
{
assemblies.Add(st);
}
}
}
}
* */
assemblies.Add("Accessibility.dll");
assemblies.Add("AspNetMMCExt.dll");
assemblies.Add("cscompmgd.dll");
assemblies.Add("CustomMarshalers.dll");
assemblies.Add("IEExecRemote.dll");
assemblies.Add("IEHost.dll");
assemblies.Add("IIEHost.dll");
assemblies.Add("Microsoft.Build.Conversion.dll");
assemblies.Add("Microsoft.Build.Engine.dll");
assemblies.Add("Microsoft.Build.Framework.dll");
assemblies.Add("Microsoft.Build.Tasks.dll");
assemblies.Add("Microsoft.Build.Utilities.dll");
assemblies.Add("Microsoft.Build.VisualJSharp.dll");
assemblies.Add("Microsoft.CompactFramework.Build.Tasks.dll");
assemblies.Add("Microsoft.JScript.dll");
assemblies.Add("Microsoft.VisualBasic.Compatibility.Data.dll");
assemblies.Add("Microsoft.VisualBasic.Compatibility.dll");
assemblies.Add("Microsoft.VisualBasic.dll");
assemblies.Add("Microsoft.VisualBasic.Vsa.dll");
assemblies.Add("Microsoft.Vsa.dll");
assemblies.Add("Microsoft.Vsa.Vb.CodeDOMProcessor.dll");
assemblies.Add("Microsoft_VsaVb.dll");
assemblies.Add("mscorlib.dll");
assemblies.Add("sysglobl.dll");
assemblies.Add("System.configuration.dll");
assemblies.Add("System.Configuration.Install.dll");
assemblies.Add("System.Data.dll");
assemblies.Add("System.Data.OracleClient.dll");
assemblies.Add("System.Data.SqlXml.dll");
assemblies.Add("System.Deployment.dll");
assemblies.Add("System.Design.dll");
assemblies.Add("System.DirectoryServices.dll");
assemblies.Add("System.DirectoryServices.Protocols.dll");
assemblies.Add("System.dll");
assemblies.Add("System.Drawing.Design.dll");
assemblies.Add("System.Drawing.dll");
assemblies.Add("System.EnterpriseServices.dll");
assemblies.Add("System.Management.dll");
assemblies.Add("System.Messaging.dll");
assemblies.Add("System.Runtime.Remoting.dll");
assemblies.Add("System.Runtime.Serialization.Formatters.Soap.dll");
assemblies.Add("System.Security.dll");
assemblies.Add("System.ServiceProcess.dll");
assemblies.Add("System.Transactions.dll");
assemblies.Add("System.Web.dll");
assemblies.Add("System.Web.Mobile.dll");
assemblies.Add("System.Web.RegularExpressions.dll");
assemblies.Add("System.Web.Services.dll");
assemblies.Add("System.Windows.Forms.dll");
assemblies.Add("System.XML.dll");
assemblies.Add("vjscor.dll");
assemblies.Add("vjsjbc.dll");
assemblies.Add("vjslib.dll");
assemblies.Add("vjslibcw.dll");
assemblies.Add("vjssupuilib.dll");
assemblies.Add("vjsvwaux.dll");
assemblies.Add("vjswfc.dll");
assemblies.Add("VJSWfcBrowserStubLib.dll");
assemblies.Add("vjswfccw.dll");
assemblies.Add("vjswfchtml.dll");
assemblies.Add("Accessibility.dll");
assemblies.Add("AspNetMMCExt.dll");
assemblies.Add("cscompmgd.dll");
assemblies.Add("CustomMarshalers.dll");
assemblies.Add("IEExecRemote.dll");
assemblies.Add("IEHost.dll");
assemblies.Add("IIEHost.dll");
assemblies.Add("Microsoft.Build.Conversion.dll");
assemblies.Add("Microsoft.Build.Engine.dll");
assemblies.Add("Microsoft.Build.Framework.dll");
assemblies.Add("Microsoft.Build.Tasks.dll");
assemblies.Add("Microsoft.Build.Utilities.dll");
assemblies.Add("Microsoft.Build.VisualJSharp.dll");
assemblies.Add("Microsoft.CompactFramework.Build.Tasks.dll");
assemblies.Add("Microsoft.JScript.dll");
assemblies.Add("Microsoft.VisualBasic.Compatibility.Data.dll");
assemblies.Add("Microsoft.VisualBasic.Compatibility.dll");
assemblies.Add("Microsoft.VisualBasic.dll");
assemblies.Add("Microsoft.VisualBasic.Vsa.dll");
assemblies.Add("Microsoft.Vsa.dll");
assemblies.Add("Microsoft.Vsa.Vb.CodeDOMProcessor.dll");
assemblies.Add("Microsoft_VsaVb.dll");
assemblies.Add("mscorlib.dll");
assemblies.Add("sysglobl.dll");
assemblies.Add("System.configuration.dll");
assemblies.Add("System.Configuration.Install.dll");
assemblies.Add("System.Data.dll");
assemblies.Add("System.Data.OracleClient.dll");
assemblies.Add("System.Data.SqlXml.dll");
assemblies.Add("System.Deployment.dll");
assemblies.Add("System.Design.dll");
assemblies.Add("System.DirectoryServices.dll");
assemblies.Add("System.DirectoryServices.Protocols.dll");
assemblies.Add("System.dll");
assemblies.Add("System.Drawing.Design.dll");
assemblies.Add("System.Drawing.dll");
assemblies.Add("System.EnterpriseServices.dll");
assemblies.Add("System.Management.dll");
assemblies.Add("System.Messaging.dll");
assemblies.Add("System.Runtime.Remoting.dll");
assemblies.Add("System.Runtime.Serialization.Formatters.Soap.dll");
assemblies.Add("System.Security.dll");
assemblies.Add("System.ServiceProcess.dll");
assemblies.Add("System.Transactions.dll");
assemblies.Add("System.Web.dll");
assemblies.Add("System.Web.Mobile.dll");
assemblies.Add("System.Web.RegularExpressions.dll");
assemblies.Add("System.Web.Services.dll");
assemblies.Add("System.Windows.Forms.dll");
assemblies.Add("System.XML.dll");
assemblies.Add("vjscor.dll");
assemblies.Add("vjsjbc.dll");
assemblies.Add("vjslib.dll");
assemblies.Add("vjslibcw.dll");
assemblies.Add("vjssupuilib.dll");
assemblies.Add("vjsvwaux.dll");
assemblies.Add("vjswfc.dll");
assemblies.Add("VJSWfcBrowserStubLib.dll");
assemblies.Add("vjswfccw.dll");
assemblies.Add("vjswfchtml.dll");
return;
}
}
}

Compile it into a separate assembly, send the assembly, have the other process load it.
You might want to consider security implications.
Update: another idea would be to generate an expression tree and use this library to serialize it:
http://www.codeplex.com/metalinq/

It is an interesting challenge, but you should probably describe why you want to do this, since there is a lot of different approaches depending on your objective. As humpohl points out, there is also some pretty serious security issues.
"Serialized code" could just be source code or a compiled assembly, depending on your requirements. You probably don't need to use a seperate code serialization format.
If you want to generate code dynamically and pass that on, you could generate code using CodeDOM and compile it. However, you most likely dont need to generate completely arbitrary code.

Another option is using the DLR, and constraining the code to execute...