Are globals still bad?

Question

I ran across some code like this today; having a flow control flag that is visible to the whole class. My gut says this is the wrong way to handle this need for flow control (it's almost like an old time global flag in C).

(The example is in VB.Net but similar things could be done in C#.)

Public Class myClass

    Private bMyFlag As Boolean ''// <------

    private sub New
        bMyFlag = false
    end sub

    private sub mySub1
        bMyFlag = true
        mySub3()
        mySub4()
        mySubN()
    end sub

    private sub mySub2
        bMyFlag = false
        mySub3()
        mySub4()
        mySubN()
    end sub

    private sub mySub3
        if bMyFlag then
            DoSomething()
        else
            DoSomethingElse()
        end if
    end sub

    private sub mySub4
        if not bMyFlag then
            DoSomethingDifferent()
        else
            DoSomethingReallyDifferent()
        end if
    end sub

    private sub mySubN
        if not bMyFlag then
            DoNotPassGo()
        else
            DoNotCollect200Dollars()
        end if
    end sub
end class

It's obvious to me that it was grafted on after the fact. I'm planning on reworking the code so that bMyFlag is a parameter passed to mySub3, mySub4, and mySuvN. However, before I do so:

Is there a valid reason for having a flow control flag that is global to the class?

Or if not, why is this considered bad practice?

Answer 1

In this case, bMyFlag seems to be introducing unnecessary state which could complicate development (debugging, etc.). Some of your subroutines modify its value, and others perform different operations based on its current value. This seems to introduce unnecessary complexity that could be reduced with some refactoring. Why not just pass a boolean value to mySub1 and mySub2, and then have those subroutines call your other functions with that value as a parameter?