static const from MC++ to C# via DLL [modified] - Managed C++/CLI Discussion Boards

Mark Salsbery10-Jan-07 14:01

10-Jan-07 14:01

hmmm does #include <windows.h> need to be before the process.h include?

Other than that all I can think of is old header files (it compiles fine for me on VS 2003).

Mark

Re: beginthread error

Mark Salsbery10-Jan-07 14:08

Mark Salsbery

10-Jan-07 14:08

1 more thought - you are compiling for multithread right (/MT)?

"Failed to load toolbox item..." [modified]

Xpnctoc9-Jan-07 17:03

Xpnctoc

9-Jan-07 17:03

OK. So I'm trying to create a custom control in a C++/CLI project. I create it, build it, it gets added to the Toolbox, everything is happy -- until I try to add the control to a Windows form. As soon as I drag the custom control from the toolbox to the form, I get the message "Failed to load toolbox item <insert name here>. It will be removed from the toolbox."

So I took a "back-to-basics" approach and tried to create a user control that merely encapsulates a textbox. Nothing else added. Just a plain old text box. I get the same $@#$@#%!#% message.

So at this point I figure either I'm just stupid or else there's something seriously wrong with my installation of Visual Studio (2005 Professional). Can someone point me to a good step-by-step article on creating custom user controls specifically in C++/CLI? Or does anyone have an idea why I'm getting this message?

Thanks.

-- modified at 11:18 Wednesday 10th January, 2007

Re: "Failed to load toolbox item..."

bsaksida10-Jan-07 9:58

bsaksida

10-Jan-07 9:58

http://users.volja.net/bsaksida/co.zip

this is my project, If you woud look for ListViewFlickerFree, you can see how to create custom control

Re: "Failed to load toolbox item..."

Xpnctoc11-Jan-07 5:28

Xpnctoc

11-Jan-07 5:28

Thanks. I've downloaded it and I'll take a look.

Re: "Failed to load toolbox item..."

Xpnctoc11-Jan-07 15:48

Xpnctoc

11-Jan-07 15:48

Bsaksida,

Just wanted to follow up with you. Thanks for that sample project. At first glance, it appeared I was doing everything correctly, but a little deeper digging revealed the problem: My project is built with the /clr option rather than /clr:pure. Once I moved my custom control into a separate DLL project built with the /clr:pure switch, I was able to bring that control into forms in the main project with no problem.

Thanks again,
xpnctoc

Re: "Failed to load toolbox item..."

bsaksida11-Jan-07 21:06

bsaksida

11-Jan-07 21:06

The reason i put in dll, was because sometimes a IDE desing bisplayed errors instead design if it wasn't in dll.

static const from MC++ to C# via DLL [modified]

ShermansLagoon7-Jan-07 23:03

ShermansLagoon

7-Jan-07 23:03

I have two projects, one "Visual C++/CLR/Class Library" (DLL file) and one "Visual C#/Windows Application"

The DLL file:

namespace Foo<br />
{<br />
  // first attempt<br />
  public ref class RC<br />
  {<br />
    public:<br />
      static const System::Int16 value = 0;<br />
  };<br />
<br />
  // second attempt<br />
  public enum class EC : System::Int16<br />
  {<br />
    value = 0;<br />
  };<br />
}

In the application I have the following problem:

static class Program {<br />
  static void Main()<br />
  {<br />
    Int16 sh = Foo.EC.value;  // error CS0266; must use explicit type cast<br />
    switch(sh)<br />
    {<br />
      case Foo.RC.value:      // error CS0150; the value is not constant<br />
        MessageBox.Show("Information");<br />
        break;<br />
    }<br />
    return 0;<br />
  }<br />

I need to solve one of these problems (which one is not that important), i.e. to have implicit type casting from an enumeration to a short (or other type of integer), or to get a "static const" defined in MC++ to actually be a constant value.
I have looked all over the net trying to find a solution for this, but it seems that this behaviour actually is what is intended, is it really so?

Forgot to add, I am using VS 2005, i.e. .NET 2.0

-- modified at 5:37 Monday 8th January, 2007

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Re: static const from MC++ to C# via DLL

User 5838528-Jan-07 12:17

User 583852

8-Jan-07 12:17

The enum should not be derived from Int16.

Use the enum type name in c# not Int16 and you should be right

System.IO.Path.IsPathRooted() does not behave as I would expect

Re: static const from MC++ to C# via DLL

ShermansLagoon8-Jan-07 20:53

ShermansLagoon

8-Jan-07 20:53

Seems like I did not explain my problem good enough;

What I need is some way of having a constant value in MC++ as an integer of any size (have several of them, some 16-bit, some 32-bit and some 64-bit), and I need the value to be viewed from C# as constant.

When trying it as a "static const" value, as seen in my question, the compiler does not regard this as a constant value. When searching forums I found out that this is what the compiler should do, becase "static const is not const" or similar quote, and I found the suggestion of having it as a typed enumeration (i.e. public enum class NAME : TYPE), just as seen in my question.

The downside on doing this is that an enum is not implicitly casted to an integer, and then I have to write:
int i = (int) myEnum.value;
with the explicit type cast each time. This is the same both with and without the enum being derived from an integer, I have tried both.

What I am hoping is that I am not the only one who have tried this, and that someone out there has found a way of doing this, but since I have googled this it does not seem like this, so that is why I asked here.

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Re: static const from MC++ to C# via DLL

led mike9-Jan-07 5:39

led mike

9-Jan-07 5:39

ShermansLagoon wrote:
get a "static const" defined in MC++ to actually be a constant value.

It is a "const". That means it is immutable. That is not the same thing as a compiler constant that is required for a case statement. C# is not C++, it has it's own definition of required const's for a case statement. I believe you need to use a different design for whatever your goal is.

led mike

Re: static const from MC++ to C# via DLL

ShermansLagoon11-Jan-07 21:58

ShermansLagoon

11-Jan-07 21:58

Ahh, ok, I understand the difference between "immutable" and "compiler constant" now. Thank you for clearing that up, lead mike.

So what I am looking for then is a way of having a "compiler constant" integer value defined in MC++, encapsulated in a .DLL class library and then regarded by C# as a "compiler constant" and as an integer value. With a "static const" it is regarded as an integer value, and the "enum class" definition is "compiler constant".
Is this possible, or should I just give up?

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Re: static const from MC++ to C# via DLL

led mike12-Jan-07 4:57

led mike

12-Jan-07 4:57

ShermansLagoon wrote:
So what I am looking for then is a way of having a "compiler constant" integer value defined in MC++

So you say, but what is the actual problem you are trying to solve. It is very likely that a different design will solve it without that requirement.

led mike

Re: static const from MC++ to C# via DLL

ShermansLagoon12-Jan-07 5:55

ShermansLagoon

12-Jan-07 5:55

I have IDL files for a CORBA subset language that until recently only compiled to C++ code. Since I wanna do the client side in a nice managed language like C# the idea was to create a compiler for the IDL files that created MC++ code that is compiled into a .DLL library.
In the IDL language there are several constant values declared, which is used similar to enumerations. In the C++ compiler they are defined as "compiler constant" values, i.e. it is possible to do neat switch-case code with their values. What I am looking for is a way of creating a IDL -> MC++ -> C# way that creates values that are equally "compiler constant", i.e. switch-case friendly. As shown in my first post I have found two ways, "static const" which are immutable but not compiler constant, and "enum class" which must be explicitly casted to integer values when used.
I hope this give you a more clear way of knowing what I really need, and that you (or anyone else) knows if this can be done or not.

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Re: static const from MC++ to C# via DLL

led mike12-Jan-07 7:12

led mike

12-Jan-07 7:12

ShermansLagoon wrote:
it is possible to do neat switch-case code with their values.

Yes because IDL is native to C++. You cannot use C++ compiler constants as C# complier constants nor can you use C++ enums as C# enums in a swtich statement. You could use C++/CLI (managed) enums in C# but that does not address your IDL code.

ShermansLagoon wrote:
I hope this give you a more clear way of knowing what I really need

No it doesn't. All you did was restate the same proposed approach you already posted. I want to know the actual project based problem you are facing. There is an alternate design that will solve that problem (whatever it is) that will not require using constants in a switch statement.

ShermansLagoon wrote:
create a compiler for the IDL files that created MC++ code

That would be a code generator not a complier, and it still does not explain what you are attempting to do with it in the C# application. As a wild guess you might need some sort of factory mechanism that would key off of the values defined in the C++/CLI module. The fact that they originate from IDL is irrelevant. It is certainly possible to accomplish this.

led mike

Re: static const from MC++ to C# via DLL

ShermansLagoon12-Jan-07 20:44

ShermansLagoon

12-Jan-07 20:44

Thanks for showing an interest and trying to help me with my problem, but unfortunately I must inform you that it is not possible to do any other design, since it is in a locked system, so I will try to do a workaround for it.

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Re: static const from MC++ to C# via DLL

ShermansLagoon26-Mar-07 0:47

ShermansLagoon

26-Mar-07 0:47

I just recently solved this problem. The keyword in MC++ for this is "literal":

namespace Foo<br />
{<br />
public ref class RC<br />
{<br />
public:<br />
literal System::Int16 value = 0;<br />
};

Which now can be used by C# as a compiler constant value:

static class Program {<br />
static void Main()<br />
{<br />
Int16 val = 0;<br />
switch(val)<br />
{<br />
case Foo.RC.value: // no longer gives CS0150<br />
 MessageBox.Show("Information");<br />
break;<br />
}<br />
return 0;<br />
}

Just wanted to tell the world, if anybody else have had a similar problem and was looking for a way to solve it Cool | :cool:

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How can i use time ?

Banks K7-Jan-07 23:02

Banks K

7-Jan-07 23:02

Hi all,

I wants to use time in using visul studio 2005(c++)which is console base application.

can any body tell me how can i use time.

thanks
bankey

Re: How can i use time ?

ShermansLagoon7-Jan-07 23:05

ShermansLagoon

7-Jan-07 23:05

What kind of "time" do you mean? The current time (found in the System::DateTime class) or do you mean a "timer" (found in class System::Windows::Forms::Timer or System::Timers::Timer).

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Re: How can i use time ?

Christian Graus8-Jan-07 9:39

Christian Graus

8-Jan-07 9:39

The answer you were given assumes you're using C++/CLI ( as that's where you asked ). If you wan tto use ANSI C++, you need to ask in the visual C++ forum. Or, just use google. There are at least 3 ways for time to be represented in C++, but there are MSDN pages that go over them all.

Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog

How to execute a function at schedule time?

Banks K7-Jan-07 21:46

Banks K

7-Jan-07 21:46

Hi all

I am try to use "ScheduleTimer.dll" which is uploaded by "Andy Brummer" article as ".NET Scheduled Timer".

But i am unable to exacute a function at schedule time by using this dll

if anybody have idea about this DLL or another method for executing a method at scheduled time please share with me.

thanks
bankey

Re: How to execute a function at schedule time?

Christian Graus8-Jan-07 9:40

Christian Graus

8-Jan-07 9:40

To execute a function at a scheduled time, you just need to set a timer to check the time, and see if the time you are looking for has elapsed. If you're having trouble using the code from an article, the message board on that article is the best place to ask.

Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog

Help with C++

Member 36662707-Jan-07 11:03

Member 3666270

7-Jan-07 11:03

I want to run an external executable file, but i'm not sure what the command line is....help?

Woohooo! I'm a tarnard.

Re: Help with C++

Christian Graus7-Jan-07 15:21

Christian Graus

7-Jan-07 15:21

In C++/CLI ( which is where you're asking ), it's process.Start. In normal C++, on windows, it's ShellExecute ( if you wanted that, I suggest asking in the right forum in future ).

It's also clear you want C++ help, you may try making your header more meaningful. Imagine if all these psots said 'help with C++' ???

If you want a standard C++ answer, none exists. ShellExecute assumes you're programmiung for windows and have access to the Windows APIs.

Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog

Re: Help with C++

Jun Du8-Jan-07 14:03

Jun Du

8-Jan-07 14:03

To add to Christian's reply, you may also use system calls such as system(), _exec() and _spawn(). They are C API, but not Windows specific.

Best,
Jun

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