In C#, how can I import all classes from one namespace into another namespace such that these classes are directly accessible from the second namespace?
I'm essentially attempting to rename a namespace in an externally visible manner.
Since code is worth a thousand words, given a DLL with the following namespace:
// Externally written DLL I have no control over.
namespace A
{
class ClassA {...}
}
I'd like to be able to create another DLL along the lines of:
// My DLL
namespace Wrapper
{
using A;
}
So that I can use it like:
// Final C# program.
using Wrapper;
var a = ClassA();
In python, I could accomplish what I want with import *:
# external.py
class ClassA:
...
# mymodule.py
from external import *
# final_program.py
import mymodule
a = mymodule.ClassA()
Disclaimer
I know this is a terrible idea, but I'm unfortunately being constrained by external requirements. The short version is that I have an external DLL that needs to interface with a proprietary system (EnScript, if you're curious). This proprietary system has restrictions on the naming of namespaces that the external DLL of course violates. Thus, I'm attempting to use the wrapper DLL to expose a namespace that is considered valid.
Related Questions
Talks about using in C# vs wildcard imports in java/python. Does not address issue of accessing from second namespace:
Import all subclasses like Java but in C#
C# equivalent to wildcard imports in Java
Namespaces in C# vs imports in Java and Python
Question about including classes in namespace. Issue was use of separate projects and so not applicable to this question:
How To Include Classes From Another Namespace In Assembly Instead of Writing Them Into A Separate DLL File?
You can't move a type to a different namespace (other than physically moving the code). The .NET type system uses the full namespace to uniquely identify the type.
But you can create an alias to mask the original namespace.
Let's say you have a class MyProject.Foo.Bar.Xyzzy.MyClass, and you are tired of typing MyProject.Foo.bar.Xyzzy. You can add a Using directive at the top of the code file like this:
Using DifferentNamespace = MyProject.Foo.Bar.Xyzzy;
Once you have done this, you can refer to the class with just
var c = new DifferentNamespace.MyClass();
You can even use this to include a different namespace in the current default namespace. This will compile:
namespace Example.Classes
{
class MyClass
{
}
}
namespace Example
{
using Example = Example.Classes;
class Test
{
static void Test1()
{
var c = new Example.MyClass(); //Not Example.Classes.MyClass
}
}
}
But unfortunately you have to leave the alias there; i.e., this won't compile:
namespace Example.Classes
{
class MyClass
{
}
}
namespace Example
{
using Example = Example.Classes;
class Test
{
static void Test1()
{
var c = new MyClass(); //Error
}
}
}
Related
I'm using IronPython for fetching inner classes from C# dll.
for example:
namespace Platform.CardHost {
internal class ExtensionManager : IExtensionManager, IDisposable {
//... other code
IronPython Code
import clr
clr.AddReference('Platform.CardHost')
import Platform.CardHost.ExtensionManager
# raise ImportError: No module named ExtensionManager
# if it add to ref
clr.AddReference('Platform.CardHost.ExtensionManager')
# raise Error
# IOError: System.IO.IOException: Could not add reference to assembly
# Platform.CardHost.ExtensionManager
How can I import ExtensionManager? Or is this not possible?
So like I already wrote:
make ExtensionManager public if you want to access it from somewhere else than your assembly.
The definition of internalis
The type or member can be accessed by any code in the same assembly, but not from another assembly.
what you could do, to make it only available for another assembly is, to make it visible for a friend assembly:
using System.Runtime.CompilerServices;
using System;
[assembly:InternalsVisibleTo("my_friend_assembly")]
internal class ExtensionManager : IExtensionManager, IDisposable
{
}
else, I don't see any reason why making it internal but trying to access it from another assembly/your ironpython-script. Yeah, for friend assemblies, there are reasons, for sure.
for your new update: "I can't change class":
so maybe, the guy who wrote that class doesn't want you to import the class from elsewhere? That's the use of internal,protected,private and public.
Imho, it would be really bad to define in C# a class as internal, so you can't import it from C#, but IronPython still lets you import it.
for sure, you could try getting the code from the assembly, change it and make it again to a new assembly, like you wrote. But that's a lot of work and possibly in the end, it won't work.
Thanks to Matthias Burger for a fact that prompted the idea.
i try to decompile dll. because the file were large after he disassemble, it can't assemble without problem.
I wrote to the guy, he say me use C# interface ICardHost.
here how i use it, maybe for someone who meet similar problem.
clr.AddReference('Platform.CardHost')
from Platform import CardHost
from Platform.CardHost import ICardHost
host = CardHost.CardHost.CreateInstance(session)
# ExtensionManager is internal class but it available by interface
# here how to use C# interface
em = ICardHost.ExtensionManager.__get__(host)
as it in C#
// cardHost
public sealed class CardHost : Component, ICardHost
// ICardHost
public interface ICardHost {
IExtensionManager ExtensionManager { get; }
I'm looking to replicate the following in IronPython and searching has so far been fruitless and/or disappointing.
namespace Groceries
{
public class ChocolateMilk : Milk
{
// Other stuff here
}
}
The idea would be that the compiled Python DLL will be loaded into a C# program through System.Reflection.Assembly.Load and a GetType("Groceries.ChocolateMilk") on the loaded DLL would not return null.
The most recent answer I was able to find was in 2008 and said that it was impossible without using the Hosting API - http://lists.ironpython.com/pipermail/users-ironpython.com/2008-October/008684.html.
Any suggestions on how to accomplish this would be greatly appreciated. Any conclusions that this is currently impossible to do via IronPython will also be appreciated, but less so.
I'm a bit confused on what you're asking here. Are you trying to instantiate that C# code in your IronPython modules? Or do you have the equivalent classes written in IronPython and you want to instantiate them in your C# code?
Based on the link you posted, I suppose you're going for the latter and have IronPython classes that you want instantiated in your C# code. The answer is, you cannot directly instantiate them. When you compile IronPython code to an assembly, you cannot use the types defined there with your regular .NET code since there is not a one-to-one mapping between IronPython classes and .NET classes. You would have to host the assembly in your C# project and instantiate it that way.
Consider this module, Groceries.py compiled to Groceries.dll residing in the working directory:
class Milk(object):
def __repr__(self):
return 'Milk()'
class ChocolateMilk(Milk):
def __repr__(self):
return 'ChocolateMilk()'
To host the module in your C# code:
using System;
using IronPython.Hosting;
using System.IO;
using System.Reflection;
class Program
{
static void Main(string[] args)
{
var engine = Python.CreateEngine();
var groceriesPath = Path.GetFullPath(#"Groceries.dll");
var groceriesAsm = Assembly.LoadFile(groceriesPath);
engine.Runtime.LoadAssembly(groceriesAsm);
dynamic groceries = engine.ImportModule("Groceries");
dynamic milk = groceries.ChocolateMilk();
Console.WriteLine(milk.__repr__()); // "ChocolateMilk()"
}
}
Otherwise to go the other way and create an instance of your .NET type in your IronPython code (as your title suggests). You'd need to add the path to your assembly, reference it, then you could instantiate it as needed.
# add to path
import sys
sys.path.append(r'C:\path\to\assembly\dir')
# reference the assembly
import clr
clr.AddReferenceToFile(r'Groceries.dll')
from Groceries import *
chocolate = ChocolateMilk()
print(chocolate)
I am trying to call my C++ library from my C# application (via C++/CLI). I followed the example from this question (for my specific application). The setup of my application is:
Project1: C++ Project (I compile this to a DLL)
Project2: C++ Project (my CLR wrapper; just the header file per the example above; references Project1)
Project3: C# Project (references Project2)
Unfortunately, when I actually go to access the CLR wrapper object in my C# application, I receive the following error:
The type or namespace name 'YourClass'
could not be found (are you missing a
using directive or an assembly
reference?)
Do I have the project setup incorrectly, or is there something else I should be looking into? (Unfortunately, I cannot post the code for proprietary reasons, but it is a very simple bit of code and easily follows the above example.)
Update:
So I did exactly what Chris said to do (see answer below), but I am still receiving a message from my C# application that "The type or namespace name 'MyProgram' could not be found (are you missing a using directive or an assembly reference?). Here is a (mock-up) of my code.
Project1 - This is my C++ application. It compiles/works. I have used it elsewhere. (I get a DLL out of this build.)
Project2 - Here is my code for my wrapper.
MyWrapper.h
#pragma once
#include "myorigapp.h"
using namespace System;
namespace MyProgram
{
public ref class MyWrapper
{
private:
myorigapp* NativePtr;
public:
MyWrapper()
{
NativePtr = new myorigapp();
}
~MyWrapper()
{
delete NativePtr;
NativePtr = NULL;
}
void dostuff()
{
NativePtr->dostuff();
}
}
}
Project3 - This is my C# application.
Program.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using MyProgram;
namespace Testing
{
class Program
{
static void Main(string[] args)
{
MyWrapper p = new MyWrapper();
p.dostuff();
}
}
}
Project3 references Project2 which references Project1. Everything builds without errors (except the error I described above in the C# code on the using MyProgram line).
Just including the header from a pure C++ application isn't good enough. You need to wrap your unmanaged objects with managed ones in Project2 (i.e. public ref class YourClassDotNet)
#include "YourHeader.h"
namespace MyManagedWrapper
{
public ref class YourClassDotNet
{
private:
YourClass* ptr;
public:
YourClassDotNet()
{
ptr = new YourClass();
}
~YourClassDotNet()
{
this->!YourClassDotNet();
}
!YourClassDotNet()
{
delete ptr;
ptr = NULL;
}
void SomeMethod()
{
ptr->SomeMethod();
}
}
}
Okay, well, I now feel dumb.
It turns out that the problem I was having (which I solved a couple weeks ago - just got around to updating this answer) was that I had included the header file (see Chris' answer for that), but I hadn't actually included the CPP file (which is empty other than including the header file).
Once I did this, the DLL compiled correctly and I could call the C++ functions (using C++/CLI) from my C# code.
Chris showed you the way to create a managed class that uses unmanaged code inside. There is a lot of that that you can do in C# using unsafe (it's just that hardly anyone does).
However, the reverse is also possible: using .NET types directly from a native type/function.
The thing to watch out for is that any managed pointer has to be marked as such. For this purpose, C++/CLI defines a special type of smartpointer gcroot<T> (mimicking boost::shared_pointer or std::auto_ptr in a way). So to store a managed string inside your C++ class, use the following:
#include <string>
#include <vcclr.h>
using namespace System;
class CppClass {
public:
gcroot<String^> str; // can use str as if it were String^
CppClass(const std::string& text) : str(gcnew String(text.c_str())) {}
};
int main() {
CppClass c("hello");
c.str = gcnew String("bye");
Console::WriteLine( c.str ); // no cast required
}
Note that (if it hasn't been fixed these days) you'll run into a bit of friction with the mismatch between managed null and C/C++ NULL.
You can't easily type, as you would expect:
gcroot<Object^> the_thing;
...
if (the_thing != nullptr)
...
}
Instead you'd have to use the native style (the smart wrapper gcroot handles this)
gcroot< Object^ > the_thing;
if ( the_thing != NULL ) {} // or equivalently...
if ( the_thing ) {}
// not too sure anymore, but I thought the following is also possible:
if ( the_thing != gcroot<Object>(nullptr) ) {}
Note: I don't have access to a windows machine anywhere near these days, so I've quoted from memory
Using .NET 2.0, C#, Windows Forms development, Enterprise Library 3.1.
We have a project namespace (call it Project). We also have several sub-namespaces inside of that project, for example Project.Namespace1, Project.Namespace2, etc.
In one class, we define enums and such to be used with the Enterprise Library Logging block, like this:
namespace Project.Logging
{
public static class Logging
{
public enum LogPriority
{
// enum values here
}
}
}
In another class, I use the enum values so I need to declare a using statement. Same project, so there is no assembly to reference, right?
If I declare the using inside of the local namespace, like this, it works fine:
namespace Project.SomeName
{
using Project.Logging;
// code referencing the Logging enum
}
However, if I put the using statement outside of the local namespace declaration, I get the "type or namespace name 'LogPriority' does not exist in the namespace 'Project.Logging'... Like this:
using Project.Logging;
namespace Project.SomeName
{
// code referencing the Logging.LogPriority.whatever
}
Why is this? Has anyone run across this before?
I have run into similar (though not exactly the same) problems before when using a class that has the same name as its namespace.
Oddly enough it seemed to compile ok on some developers pc's but not on others. In the end we made sure that no namespace contained a class of the same name.
namespace Project.Logging
{
public static class Logging // this is what caused the probems for me
{
}
}
I also had a wired error. I cannot find any namespace which is coming from different assemblies, but begins with executing assembly name.
Finally, I found out that I have set the target framework to .NET framework client profile.
Yes, most likely you have an unusual value set for the "Default Namespace" in your project properties. I would validate the project configuration.
We ran into this issue before and it all went down to ambiguous naming of the namespace and the class name.
When we tried to have our namespace as Services.Web.xxx and also add in a service reference as Services.Web.xxxx and ALSO add a references to an assembly that was named Services.Web.xxx you can only imagine the problems we ran into.
In the end to fix it we simply did a rename to make sure that there was only one instance of the Services prefix
Also you could do the following and create an alias to LogPriority to LogEnum:
using LogEnum= Project.Logging.Logging.LogPriority;
namespace Project.SomeName
{
internal class MyClass
{
public MyClass()
{
LogEnum enum1 = LogEnum.None;
}
}
}
namespace Project.Logging
{
public static class Logging
{
public enum LogPriority
{
None,
Default
}
}
}
It definitely can make a difference if you have usings inside or outside the namespace. There is a good discussion here, and it is likely to be related to your default namespace settings.
I've made a simple C# DLL (that's part of a much larger project) using VS2005. I need to use the DLL in Excel via VBA code so I am using COM Interop on the assembly. I am trying to make the build process automatically generate the necessary TLB file so that I don't need to go to the command line and use regasm after every build.
My problem is that although the DLL compiles and builds fine, it does not generate a TLB file. Instead, the error in the title prints out in the output box.
I've gotten other DLLs to build TLB files by going to the project's properties in VS2005 -> Build -> Output -> Check "Register for COM interop". Also I have [assembly: ComVisible(true)] in the AssemblyInfo.cs.
Here's the summary of the source for the problem DLL and the DLL that it references for a return type:
using System;
using System.IO;
using System.Runtime.InteropServices;
using SymbolTable;
namespace ProblemLibrary
{
public class Foo
{
public Foo(string filename)
{
...
}
// method to read a text file into a SymbolTable
public SymbolTable BuildDataSet(string[] selected)
{
...
}
}
}
Here is a summary of SymbolTable.dll. It holds a return type that ProblemLibrary uses.
using System;
using System.Collections.Generic;
namespace SymbolTable
{
public class SymbolTable
{
readonly Dictionary<SymbolInfoStub, string> _symbols = new Dictionary<SymbolInfoStub, string>();
/*methods that interact with Dictionary snipped*/
}
}
You need to have ctor without any params.
You should have GuidAttribute and ProgIdAttribute around the classes.
Its better to mark the assembly as ComVisible(false) and mark explicitly the classes that need export.
Use interfaces for your classes.
Make sure the you have GuidAttribute in the assembly level.
[Guid("<PUT-GUID-HERE-1>")]
[ComVisible(true)]
interface IFoo
{
void DoFoo();
}
[Guid("<PUT-GUID-HERE-2>")]
[ComVisible(true)]
[ProgId("ProgId.Foo")]
class Foo : IFoo
{
public void DoFoo()
{
}
}
In the AssemblyInfo.cs file, make sure you have the following:
// Setting ComVisible to false makes the types in this assembly not visible
// to COM components. If you need to access a type in this assembly from
// COM, set the ComVisible attribute to true on that type.
[assembly: ComVisible(true)]
UPDATE:
Read: How can I make use of .NET objects from within Excel VBA?
Which links to:
http://richnewman.wordpress.com/2007/04/15/a-beginner%E2%80%99s-guide-to-calling-a-net-library-from-excel/
I saw a similar problem. I got an error like:
warning MSB3391: does not contain any
types that can be unregistered for COM
Interop.
I followed all the rules (ComVisible, etc.) but nothing worked.
Solution: I had to put something in the default constructor so that it would not be optimized away. The moment I had something there, the registration finished with no message and the component was visible in the registry.
Interesting note: a friend of mine managed to register the original DLL with the empty default constructor on his machine (64-bit Windows-7, VS2008-Professional, like mine). However, his REGASM.EXE was:
C:\Windows\Microsoft.NET\Framework64\v2.0.50727\regasm.exe
while mine was:
C:\Windows\Microsoft.NET\Framework64\v4.0.30319\RegAsm.exe
So it could be some difference between versions of the .NET framework - maybe the later version is optimizing too much and the REGASM does not account for that.