Bug or feature?
in [Visual Basic]
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From: C. Kevin Provance on 7 Jun 2010 21:18 I discovered a hell of a thing: I have this is a standard module: Public Property Get LoadPercent() As Long mlLoadPercent = mlLoadPercent + 6 LoadPercent = mlLoadPercent End Property mlLoadPercent is a module level variable. When I call LoadPercent from anywhere within my code, break the code on the line that calls LoadPercent and mouseover the LoadPercent, which displays it's current value, the value displayed in the tooltip incrases with each mouseover. How's that for messed up!
From: Karl E. Peterson on 7 Jun 2010 21:30 C. Kevin Provance laid this down on his screen : > I discovered a hell of a thing: > > I have this is a standard module: > > Public Property Get LoadPercent() As Long > > mlLoadPercent = mlLoadPercent + 6 > > LoadPercent = mlLoadPercent > > End Property > > mlLoadPercent is a module level variable. > > When I call LoadPercent from anywhere within my code, break the code on the > line that calls LoadPercent and mouseover the LoadPercent, which displays > it's current value, the value displayed in the tooltip incrases with each > mouseover. How's that for messed up! Makes sense. Each time you wave the mouse over, the property procedure is called to retrieve the value. Since simply calling the procedure increments it, well... Put it in a class, and make the class persistent, same thing... Private Sub Command1_Click() Dim c As Class1 Set c = New Class1 Debug.Print c.LoadPercent End Sub I guess it's a pretty good example why you wouldn't want the property procedure calculating a new value based on anything but external criteria (memory load, etc)? -- ..NET: It's About Trust! http://vfred.mvps.org Customer Hatred Knows No Bounds at MSFT ClassicVB Users Regroup! comp.lang.basic.visual.misc Free usenet access at http://www.eternal-september.org
From: Charlie on 8 Jun 2010 13:21 Bug or feature? Well that depends... If I wrote it it's a bug, if my boss wrote it it's a feature! ;) "C. Kevin Provance" wrote: > I discovered a hell of a thing: > > I have this is a standard module: > > Public Property Get LoadPercent() As Long > > mlLoadPercent = mlLoadPercent + 6 > > LoadPercent = mlLoadPercent > > End Property > > mlLoadPercent is a module level variable. > > When I call LoadPercent from anywhere within my code, break the code on the > line that calls LoadPercent and mouseover the LoadPercent, which displays > it's current value, the value displayed in the tooltip incrases with each > mouseover. How's that for messed up! >
From: Jeff Johnson on 9 Jun 2010 11:38 "C. Kevin Provance" <*@*.*> wrote in message news:huk5ov$7cs$1(a)news.eternal-september.org... >I discovered a hell of a thing: > > I have this is a standard module: > > Public Property Get LoadPercent() As Long > > mlLoadPercent = mlLoadPercent + 6 > > LoadPercent = mlLoadPercent > > End Property > > mlLoadPercent is a module level variable. > > When I call LoadPercent from anywhere within my code, break the code on > the > line that calls LoadPercent and mouseover the LoadPercent, which displays > it's current value, the value displayed in the tooltip incrases with each > mouseover. How's that for messed up! Sounds like what you just "discovered" is the concept of "side effects." And now you know why they're considered a bad thing.
From: Karl E. Peterson on 9 Jun 2010 13:20 Jeff Johnson explained : > "C. Kevin Provance" <*@*.*> wrote in message > news:huk5ov$7cs$1(a)news.eternal-september.org... > >>I discovered a hell of a thing: >> >> I have this is a standard module: >> >> Public Property Get LoadPercent() As Long >> >> mlLoadPercent = mlLoadPercent + 6 >> >> LoadPercent = mlLoadPercent >> >> End Property >> >> mlLoadPercent is a module level variable. >> >> When I call LoadPercent from anywhere within my code, break the code on the >> line that calls LoadPercent and mouseover the LoadPercent, which displays >> it's current value, the value displayed in the tooltip incrases with each >> mouseover. How's that for messed up! > > Sounds like what you just "discovered" is the concept of "side effects." And > now you know why they're considered a bad thing. I'd disagree. It's *cool* to be able to hover over something to get its value. But you need to know what it is you're hovering over. If it's a variable, that's what you get. If it's, in essence, a function then you need to expect (or deduce) that the function has to execute to return a value. What's interesting, though, is the "in essence" part of this. You don't get the retval from an actual function by hovering over it. That only happens with object properties. It's a good heads-up! I never really thought about how that'd all play out until it was posted here. -- ..NET: It's About Trust! http://vfred.mvps.org Customer Hatred Knows No Bounds at MSFT ClassicVB Users Regroup! comp.lang.basic.visual.misc Free usenet access at http://www.eternal-september.org
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