I need help with Implements - Xtreme Visual Basic Talk

08-30-2004, 10:37 AM

KentLam

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Posts: 3

I need help with Implements

Hi everyone,
I am pretty new to VB. I'm more of a Java programmer, so I am a little lost to the way VB uses Implements.

I need to know if it's possible to "Implements" a class with abstract functions as well as concrete functions. I can Implements a class with all abstract functions, that's simple, but I need some concrete functions in that class as well.

Please help asap, thanks in advance.

-Kent

08-30-2004, 11:36 AM

lebb

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You mean your interface class would have some concrete functions that would get inherited? No, VB6 doesn't support that. If I've misunderstood your question, please clarify.

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08-30-2004, 12:46 PM

KentLam

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Exactly what you meant, too bad VB doesn't support that. Hmm, I gotta think of something else. Thanks for your response.

08-30-2004, 02:24 PM

lebb

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If you need true inheritance, you should probably consider VB.NET. If that's not an option, feel free to share the specifics of your need and we can probably help with a workaround.

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08-30-2004, 02:38 PM

Mike Rosenblum Mike Rosenblum is offline

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Edit: LOL, too slow again... I'm two for two today, L!

Using Implements in VB6 basically provides Properties, Functions, and Subs in an abstract manner only. However, you can make it fairly concrete rapidly by passing in an Instance of the Implemented Class and rely on the functionality therein...

As an example, IClass could look something like this:

Code:

' --------------------------------------------
' IClass

Option Explicit

Property Get MyType() As String
    MyType = TypeName(Me)
End Property

Sub SomeMethod()
    MsgBox "SomeMethod() Called"
End Sub

While clsMyClass could Implement IClass using something like this:

Code:

' --------------------------------------------
' clsMyClass

Option Explicit

Implements IClass
Dim m_IClass As IClass

' --------------------------------------------
' pvtInit() acts as Contructor:

Friend Function pvtInit(oIClass As IClass) As clsMyClass
    Set m_IClass = oIClass
    Set pvtInit = Me
End Function

' --------------------------------------------
' IClass Implementation (Required):

Private Property Get IClass_MyType() As String
    IClass_MyType = m_IClass.MyType
End Property

Private Sub IClass_SomeMethod()
    Call m_IClass.SomeMethod
End Sub

' --------------------------------------------
' Exposed as clsMyClass members (Optional):

Property Get MyType() As String
    MyType = m_IClass.MyType
End Property

Sub SomeMethod()
    Call m_IClass.SomeMethod
End Sub

I realize that this is fairly crude compared to a real OOP language, but I think this kinda gets you there (unless I didn't understand what you meant?).

Btw, if you're comfortable with Java, I think you'd likely like VB.Net a lot...

-- Mike

Last edited by Mike Rosenblum; 08-30-2004 at 05:41 PM.

08-30-2004, 05:31 PM

KentLam

Newcomer

Join Date: Aug 2004

Posts: 3

Quote:

Originally Posted by Mike_R

Edit: LOL, too slow again... I'm two for two today, L!

Using Implements in VB6 basically only provides Properties, Functions, and Subs in an abstract manner only. However, you can make it fairly concrete rapidly by passing in an Instance of the Implemented Class and rely on the functionality therein...

As an example IClass could look something like this:

Code:

' --------------------------------------------
' IClass

Option Explicit

Property Get MyType() As String
    MyType = TypeName(Me)
End Property

Sub SomeMethod()
    MsgBox "SomeMethod() Called"
End Sub

While clsMyClass could Implement IClass using something like this:

Code:

' --------------------------------------------
' clsMyClass

Option Explicit

Implements IClass
Dim m_IClass As IClass

' --------------------------------------------
' pvtInit() acts as Contructor:

Function pvtInit(oIClass As IClass) As clsMyClass
    Set m_IClass = oIClass
    Set pvtInit = Me
End Function

' --------------------------------------------
' IClass Implementation (Required):
Private Property Get IClass_MyType() As String
    IClass_MyType = m_IClass.MyType
End Property

Private Sub IClass_SomeMethod()
    Call m_IClass.SomeMethod
End Sub

' --------------------------------------------
' Exposed as clsMyClass members (Optional):

Property Get MyType() As String
    MyType = m_IClass.MyType
End Property

Sub SomeMethod()
    Call m_IClass.SomeMethod
End Sub

Thank you Mike and Lebb for your responses.

VB was actually one of the first PL I learned in high school.
Went I got to college, all they had was Java, and so four years of Java and nearly forgot everything about VB. Do you think VB.Net is a good choice for me? I've considered it, but haven't really look into it. I'll check it out sometimes this week. Thanks for the pointer.

08-30-2004, 05:39 PM

Mike Rosenblum Mike Rosenblum is offline

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Four years of Java? VB 6 would be a big step back for you. You'll find that VB.Net borrowed a ton from Java. So, yes, I definately think you should give .Net a look...

You may find these links of interest btw:

(1) Basic Inheritance in VB.Net
(2) VB.Net Tutors Corner
(3) VB.Net Code Library

-- Mike

Last edited by Mike Rosenblum; 08-30-2004 at 05:47 PM.

08-30-2004, 06:13 PM

lebb

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Likewise, if you've enjoyed Java, you might want to give C# a try, since it has mostly Java syntax but is otherwise extremely similar to VB.NET.

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