Exposing C# to COM / Inheritance of objects/interfaces - C# Discussion Boards

20-Sep-06 2:45

I have a function GetVersion() that returns the version (e.g. 1.0) and I want to achieve this:

When I do MessageBox.Show(GetVersion()) to display 1.0 as a version.
When I do MessageBox.Show(GetVersion().Major()) to display 1
and when MessageBox.Show(GetVersion().Minor()) to display 0.

Parsing isn't issues here, but how to implement this GetVersion().SomeMethod().

I have tried this with the class with its methods:

public SomeClass GetVersion()
{
// Code
}

But this function required to return a value od type SomeClass and I need a string to return.

I don't know how to return a string with GetVersion() becouse GetVersion is type of SomeClass.

Or I can try by inheriting the Strings class and implement those two functions in that inherited class?

User 665820-Sep-06 2:55

User 6658

20-Sep-06 2:55

Your GetVersion() will need to return a type that implements GetMajor and GetMinor itself. Here is an example:

class VersionInfo
{
    public int Major
    {
         get { return major; }
         set { major = value; }
    }

    public int Minor
    {
         get { return minor; }
         set { minor = value; }
    }

    private int major;
    private int minor;

    public override string ToSting()
    {
         return major + "." + minor;
    }
}

class SomeClass
{
     public static VersionInfo GetVersion()
     {
          VersionInfo temp = new VersionInfo();
          temp.Major = 1;
          temp.Minor = 0;
     }
}

You can then use SomeClass.GetVersion() to get a VersionInfo, or SomeClass.GetVersion().Major or SomeClass.GetVersion().Minor

I modified your GetMajor() and GetMinor() functions to use properties. It's the preferred way in C# to access attributes of a class.

regards

modified 12-Sep-18 21:01pm.

Kasic Slobodan20-Sep-06 5:34

20-Sep-06 5:34

Hmm. It refuses to work afterall.

In GetVersion() function it fails to compile with the error that it cannot be implicitly convert from string to VersionInfo.

Any ideas?

S. Senthil Kumar20-Sep-06 5:54

S. Senthil Kumar

20-Sep-06 5:54

The implicit[^] conversion operator does just what you want. Try this piece of code

class VersionInfo
{
    private string majorVersion = "1";
    private string minorVersion = "0";

    public static implicit operator string(VersionInfo versionInfo)
    {
        return versionInfo.majorVersion + "." + versionInfo.minorVersion;
    }

    public string GetMajorInfo()
    {
        return majorVersion;
    }

    public string GetMinorInfo()
    {
        return minorVersion;
    }
}

Make GetVersion return an instance of VersionInfo and you're done.

Regards
Senthil [MVP - Visual C#]
_____________________________
My Blog | My Articles | My Flickr | WinMacro

Kasic Slobodan20-Sep-06 6:32

20-Sep-06 6:32

This works, but it has something that its not like I wanted to do.

I read from Xml file version in GetVersion function. You have inicialized major and minor in VersionInfo class.

I tried to set the values like VersionInfo v = new VersionInfo; x.MajorInof = 1; and to use this instance as a return of a function, but this fails.

Can I somehow read Xml file in GetVersion function with this code or to read Xml file in VersionInfo class?

Sorry fot boder you...

Kasic Slobodan20-Sep-06 6:42

Exposing C# to COM / Inheritance of objects/interfaces

20-Sep-06 6:42

I solved it.

I set Major and Minor to be type of int instead of string and now it works with VersionInfo v = new VersionInfo(); x.Major = 1; x.Minor = 0; set in GetVersion() function where I read from Xml.

Now I have to use ToString() when using GetVersion().Major or .Minor, but that's not the problem.

Thank you both for your time.

Adam Clauss20-Sep-06 2:21

Adam Clauss

20-Sep-06 2:21

First, I have ComVisible set to true for the entire assembly.

I have (abstract) base class A. There are interfaces IA and IAEvents for accessing properties of this object and exposing events.

[ClassInterface(ClassInterfaceType.None), ComSourceInterfaces(typeof(IAEvents))]
public abstract class A : IA
{
...
}

I then have a derived class B and an interface IB (IB also derives from IA).

public class B : A, IB
{
...
}

Given an instantiation of B, I can access (from COM) properties/methods defined in either IA or IB.

However, when I then add a IBEvents (deriving from IAEvents) and change class B to:

[ClassInterface(ClassInterfaceType.None), ComSourceInterfaces(typeof(IBEvents))]
public class B : A, IB
{
...
}

I can no longer access methods/properties defined from A/IA. Only those defined at the B level. Commenting out the attributes on B will make it work, but of course the new events from IBEvents do not exist. Is there some wierd trick with regards to inheritance and COM that is preventing this? Is it still possible to do what I want? I intend to have a great many classes deriving from A each with their own unique set of properties and events in addition to the 'base' ones defined in A.
Ideas?

Adam Clauss

Trim textbox

Yustme20-Sep-06 2:14

20-Sep-06 2:14

Hi,

I made a few textboxes where a user would put data in.

If the first box has data entered, it should enable the next textbox.

The problem is, what can i do if the user presses a few times the spacebar.

Because the next textbox will be enabled.

Thanks in advance!

Sebastian Schneider20-Sep-06 2:29

Sebastian Schneider

20-Sep-06 2:29

You can trim the Text property just like you would trim a string (thats just what the Text property is).

I am not sure if that was your problem, though. It reads like you are referring to setting input focus to the next textbox? Please clarify.

Cheers,
Sebastian

--
Contra vim mortem non est medicamen in hortem.

Yustme20-Sep-06 2:39

20-Sep-06 2:39

Hi Sebastian,

Maybe you understand the code better than my words Big Grin | :-D

private void Textbox1_TextChanged(object sender, EventArgs e)
{
this.Textbox1.Text.Trim();

if (this.TBLicensePlateCar.Text == string.Empty)
{
MessageBox.Show("Nothing is typed", "Information", MessageBoxButtons.OK, MessageBoxIcon.Information);
}

else
{
this.data = this.Textbox1.Text;
this.NextTextBox.Enabled = true;
}
}

One char is enough to enable the next textbox. But is shouldn't be a space.

J4amieC20-Sep-06 2:54

J4amieC

20-Sep-06 2:54

Yustme wrote:
this.Textbox1.Text.Trim();

This line returns a new string, so you must assign it to something otherwise the trimmed copy of the string is lost. Probably what you wanted was

this.Textbox1.Text = this.Textbox1.Text.Trim();

---

How to get answers to your questions[^]

Yustme20-Sep-06 3:10

20-Sep-06 3:10

Hi J4amieC,

That worked! Thanks.

I do get the messageBox twice now. Wonder how this keeps happening...

Sebastian Schneider20-Sep-06 3:21

Sebastian Schneider

20-Sep-06 3:21

My guess: The text-changed event fired again.

Scenario:

User enters a "space" in the first textbox. The text-changed event fires.
The method gets called. The string is trimmed (now empty) and stored in the Text-Property. The new text (empty) is different from the old text (space) so the text-changed event fires AGAIN.
Completion of the first call occurs (MessageBox and all).
The method gets called again for the second text-changed event. This time, trimming yields the same string as before, so no change occurs.
Completion of the second call occurs (MessageBox and all).

You could either remove the handling from the text-changed-event during the trim (not sure if that works) or you could actually compare the new string to the old one and return immediately if they match.

And I am sure there is a better way Wink | ;)

Cheers,
Sebastian

--
Contra vim mortem non est medicamen in hortem.

Yustme20-Sep-06 3:52