I have this algorithm that I want to implement on VB6.
Sub Main()
dim stringVal1 as string, stringVal2 as string
dim getOne as boolean
stringVal1 = "FunctOne"
stringVal2 = "FunctTwo"
if getOne then
'Call Function with function name assigned to stringVal1 ... how to call the function here?**
开发者_JAVA技巧else
'Call Function with function name assigned to stringVal1 ... how to call the function here?**
end if
End Sub
Function FunctOne()
Msgbox "I'm function one"
End Function
Function FunctTwo()
Msgbox "I'm function two"
End Function
Can this be done in VB6?
Generally, such code patterns point to errors in your software design.
In the rare cases where this is really needed, CallByName
accomplishes this.
Example:
Call CallByName(Me, "NameOfFunction", vbMethod, arguments)
It would help if you give more information about why you're needing to call functions by the string representation of their name. Could you not simply re-write your code like this:
If getOne Then
Call FuncOne()
Else
Call FuncTwo()
End If
Generally, you don't want to actually dispatch based on Strings. This is error-prone (as you have to be really sure at run time that your String has the function name you want), and really unnecessary. The way to do this sort of thing where you want to be able to "pass in" the method that you want to use would be to use the polymorphism that VB has, and use a separate Class for each implementation.
In the Class Module that you use for your interface, say named MyInterface
:
Public Sub DoStuff()
End Sub
Then, create two Class Modules, one for each possible implementation of the Interface:
In MyClassOne
:
Implements MyInterface
Public Sub MyInterface_DoStuff()
Msgbox "I'm function one"
End Sub
Then, in MyClassTwo
, the same thing but with your other implementation:
Implements MyInterface
Public Sub MyInterface_DoStuff()
Msgbox "I'm function two"
End Sub
To use it, you just need to pass in which implementation you want to use:
Private Sub UseInterface(WhichThingToUse as MyInterface)
WhichThingToUse.DoStuff
End Sub
Rather than using a String variable to store which method to use, you need to instead store a New MyClassOne
or a New MyClassTwo
. You don't show how your getOne
variable gets set, but whatever the logic is for it, you just need to change to store an instance of MyInterface instead, and just use that directly.
For further reading in the MSDN library:
- How Visual Basic Provides Polymorphism
- Creating and Implementing an Interface
- Creating Interfaces for Use With the Implements Statement
- Implements Statement reference
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