.NET (Core and Framework)

Class Inheritance [modified]

30-Aug-07 4:49

I've used it as part of their reporting suite - it's very good. Plus, you can get the source code so you can do with it what you want.

Deja View - the feeling that you've seen this post before.

Re: PrintPreviewControl

RJKMinotaur30-Aug-07 6:07

RJKMinotaur

30-Aug-07 6:07

Thanks, I appreciate it. I already have an email into them for clarification.

#realJSOP29-Aug-07 8:36

29-Aug-07 8:36

I have an abstract class, like so:

abstract class BaseClass
{
    protected int m_n1;
    protected string m_s1;
    protected string m_s2;

    public BaseClass(int n1, string s1, string s2)
    {
        m_n1 = n1;
        m_s1 = s1;
        m_s2 = s2;
    }

    protected abstract void MyFunction();

}

I'm trying to derive from it like this:

public class MyClass: BaseClass
{
    public MyClass(int n1, string s1, string s2) : base(n1, s1, s2)
    {
    }

    protected override void MyFunction()
    {
        // do something here
    }
}

The compiler is telling me this

<code>No overload for method 'BaseClass' takes '3' arguments</code>

What am I doing wrong?

-- modified at 15:20 Wednesday 29th August, 2007

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-----
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Pete O'Hanlon29-Aug-07 9:03

29-Aug-07 9:03

Well - apart from anything else, the code doesn't build. If you can't compile up BaseClass the compiler can't match up the base call. You need to change your reference to s1 to m_s1 in the member declaration.

protected string m_s1;

Deja View - the feeling that you've seen this post before.

#realJSOP29-Aug-07 9:19

29-Aug-07 9:19

Well, the examples I gave are simple that - examples. The code I'm working on does compile except for the error I've mentioned which has nothing to do with data members. I did "fix" that, but as I said, that's not the problem in the actual code.

Another thing I've noticed... Intellisense doesn't present me with a list of parameters when I type :base(.

Pete O'Hanlon29-Aug-07 9:21

29-Aug-07 9:21

Then post the definition of the classes (down to constructor level only).

Deja View - the feeling that you've seen this post before.

#realJSOP29-Aug-07 9:23

29-Aug-07 9:23

Look at my modified response that you just replied to (about intellisense).

Luc Pattyn29-Aug-07 9:38

Luc Pattyn

29-Aug-07 9:38

Hi John,

please don't modify the original messages without a trace, it makes it
impossible to understand the chronology of the thread.

if Intellisense does not show you either did something wrong (like missing a
file in a project) or VS just got confused; so I would suggest you try deleting
the bin and obj folder(s) (except for your own additions to them), close and
reopen VS, and rebuild all.

What's your VS version?

Hope this helps.

Luc Pattyn [Forum Guidelines] [My Articles]

this weeks tips:
- make Visual display line numbers: Tools/Options/TextEditor/...
- show exceptions with ToString() to see all information
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#realJSOP29-Aug-07 9:50

29-Aug-07 9:50

Luc Pattyn wrote:
please don't modify the original messages without a trace, it makes it
impossible to understand the chronology of the thread.

If you read the thread, you'll understand the chronology. I simpky forgot to put a m_ in front of a variable name.

Luc Pattyn wrote:
f Intellisense does not show you either did something wrong (like missing a
file in a project)

Not that I can see - the line class MyClass: BaseClass is correctly syntax highlighted, so I know it sees BaseClass.

Luc Pattyn wrote:
so I would suggest you try deleting
the bin and obj folder(s) (except for your own additions to them), close and
reopen VS, and rebuild all

Already did all that - intellisense still doesn't show the parameter list, and the compiler still chokes and claims there's no overloaded member with the correct number of arguments.

As you can see by the code posted in the original message, there doesn't appear to be anything wrong.

I've tried changing the base constructor to be protected

I've tried adding a default constructor.

I've even tried adding :this() to the constructor in the base class.

I'm out of ideas.

#realJSOP29-Aug-07 9:38

29-Aug-07 9:38

Could it be that the derived class is in a namespace and the base class isn't?

Pete O'Hanlon29-Aug-07 10:11

29-Aug-07 10:11

Nope - that shouldn't affect it. Without actually seeing the code we're really shooting in the dark with this. Some things to look at though:

The accessibility level of the constructor shouldn't be an issue if the base class has a protected constructor.
If the base class is in a separate project, try building that project on its own - problems compiling that project will have an effect on the derived class (which means that you will see the issue with Intellisense not picking the definition up).
A silly one, and one I suspect you've already ruled out - the parameters must be the correct types between the call to base and the constructor in the base class.

Deja View - the feeling that you've seen this post before.

#realJSOP29-Aug-07 10:14

29-Aug-07 10:14

Check out the last message in this thread. :/

#realJSOP29-Aug-07 10:13

29-Aug-07 10:13

SOLVED

Here's what I found.

I have a solution with a project in it that represents an application.

I've added a second project to the solution that represents a DLL (asembly) to be used by the application.

I added a new class (my base class) to the solution, and VS2005 placed the cs file into a folder called Solution Items.

In the assembly, I need to derive from the base class. The only way I could derive from the class was to "add existing item" and select the file.

Unbeknownst to me, the IDE created a copy of the file int he assembly's folder.

I was still editing the copy of the base class that was in the Solution Items folder (which had the desired constructor), but the assembly project was compiling its own local copy. When I added the constructor to the local copy, it compiled fine.

So, do I have to compile the base class into it's own assembly in order to derive from it without this file duplication problem?

Pete O'Hanlon29-Aug-07 10:21

29-Aug-07 10:21

Nope - remove the one from the Solution Items folder. Basically, that's an entry that doesn't form part of an assembly (and won't be compiled). You could use a separate assembly for it, but based on your description here I don't see that you really need to do this.

Deja View - the feeling that you've seen this post before.

#realJSOP29-Aug-07 10:31

29-Aug-07 10:31

Well, this is going to be used by more than one aassembly, so should it be in it's own assembly? (What a hassle...)

Pete O'Hanlon29-Aug-07 10:36

29-Aug-07 10:36

If it's to be used by more than one assembly then yes - that's the best option.

Deja View - the feeling that you've seen this post before.

#realJSOP29-Aug-07 10:50

VB application breaks with dll built with Framework 2.0

29-Aug-07 10:50

Many thanks.

saswatpadhan29-Aug-07 7:48

saswatpadhan

29-Aug-07 7:48

Hi guys,

I am calling a managed dll build in 2.0 from a vb 6.0 application, the dll runs well under clr 2.0 but the vb application breaks.

I was previously using managed dll built with 1.1, and that was working fine. i have framework 1.1 and 2.0 installed with windows server 2003.

can u guys tell me what could be the problem??

Thank You.

Saswat

Re: VB application breaks with dll built with Framework 2.0

Pete O'Hanlon29-Aug-07 9:04