Object-Oriented Programming in VB6-implement class inheritance

Specifically, VB6 cannot implement class inheritance in the true sense (for example, inheritance in C ++), but implements also provides similar functions.

 

 

We first create a class module cbase. CLs

The Code is as follows:

Private mvarbaseproperty as string

Public sub basefunction ()

Msgbox "Hello world !"

End sub

Public property let baseproperty (byval vdata as string)

Mvarbaseproperty = vdata

End Property

Public property get baseproperty () as string

Baseproperty = mvarbaseproperty

End Property

 

 

Next we will create a new type of module (cinherit. CLs). The Code is as follows, with key comments.

 

 

Implements cbase ''' note this keyword

Dim m_baseproperty as string

''''---------------------------------------------------------------------

''' The code between the dotted lines is inherited from the cbase class.

''' Note that the format is as follows: base class _ attribute name (or method name)

'''' The Declaration keyword of its method is also changed to private

Private property get cbase_baseproperty () as string

Baseproperty = m_baseproperty

End Property

Private property let cbase_baseproperty (byval vdata as string)

M_baseproperty = vdata

End Property

Private sub cbase_basefunction ()

Msgbox "inherit"

End sub

''''---------------------------------------------------------------------

''' This method inherits the class's own method.

Public sub inheritmsg ()

Msgbox "My owner MSG"

End sub

 

 

Now we create a new form for testing. We place the test code in the form_load event.

 

 

 

 

Test 1:

Dim objtest as cbase

Set objtest = new cbase

With objtest

. Basefunction

End

Set objtest = nothing

Run the program. The base is displayed, indicating that the basefunction function in CBSE is called.

 

 

Test 2:

Dim objtest as cbase

Set objtest = new cinherit

With objtest

. Basefunction

End

Set objtest = nothing

Run the program and pop up inherit, which indicates that the base function in cinherit is called.

 

 

Test 3:

Dim objtest as cinherit

Set objtest = new cinherit

With objtest

. Inheritmsg

End

Set objtest = nothing

Run the program. The my owner function is displayed, indicating that the inherited class can use its own functions or attributes.