I thought the problems w/goto centered around code readability/human understandability. Does it matter how different constructs compile down to IL?
-----Original Message----- From: Discussion of advanced .NET topics. [mailto:[EMAIL PROTECTED] On Behalf Of Roy Green Sent: Wednesday, June 21, 2006 11:05 AM To: [email protected] Subject: Re: [ADVANCED-DOTNET] Exit Do... Funny you should mention that. Here is a deeply nested do loop in VB.NET from Wei-Meng Lee's Sudoku book, that Reflector showed as a series of If-Then-Else statements each having a goto statement pointing to the top of the series (not only that, but the IL didn't consolidate the NOP targets, so for instance, if there are 10 nested do loops, each Exit Do pointed to its own NOP. Do '---Look for Triplets in Columns Do '---Look for Triplets in Rows Do '---Look for Triplets in Minigrids Do '---Look for Twins in Columns Do '---Look for Twins in Rows Do '---Look for Twins in Minigrids Do '---Look for Lone Ranger in Columns Do '---Look for Lone Ranger in Rows Do '---Look for Lone Ranger in ' Minigrids Do '---Perform Col/Row and ' Minigrid Elimination changes = _ CheckColumnsAndRows() If (HintMode AndAlso changes) _ OrElse IsPuzzleSolved() Then ExitLoop = True Exit Do End If Loop Until Not changes If ExitLoop Then Exit Do '---Look for Lone Ranger in ' Minigrids changes = _ LookForLoneRangersinMinigrids() If (HintMode AndAlso changes) _ OrElse IsPuzzleSolved() Then ExitLoop = True Exit Do End If Loop Until Not changes If ExitLoop Then Exit Do '---Look for Lone Ranger in Rows changes = LookForLoneRangersinRows() If (HintMode AndAlso changes) OrElse _ IsPuzzleSolved() Then ExitLoop = True Exit Do End If Loop Until Not changes etc. on up the chain.... In Reflector, this broke down to.. Label_0005: Label_0006: Label_0007: Label_0008: Label_0009: Label_000A: Label_000B: Label_000C: Label_000D: Do flag1 = Me.CheckColumnsAndRows If Me.IsPuzzleSolved Then flag2 = True Exit Do End If Loop While flag1 If Not flag2 Then flag1 = Me.LookForLoneRangersinMinigrids If Me.IsPuzzleSolved Then flag2 = True ElseIf flag1 Then goto Label_000D End If End If If Not flag2 Then flag1 = Me.LookForLoneRangersinRows If Me.IsPuzzleSolved Then flag2 = True ElseIf flag1 Then goto Label_000C End If End If etc..... In any case, compilers, whether targeting intermediate or machine code, often make use of unconditional branches (i.e. IL or ML "goto") to express higher level logic. "We do the dirty work, so you don't have to..." On 6/21/06, Mike Andrews <[EMAIL PROTECTED]> wrote: > Hmmm.... > > I'm still not entirely convinced, but they do make good cases for GOTO. > I suppose I need to look at the IL from a VB program with Exit Do > nested inside a Select Case statement inside a Do loop. > Perhaps it just inserts goto statements itself. > > > > > On 6/20/06, Roy Green <[EMAIL PROTECTED]> wrote: > > > > Michael Covington had a great article about restoring the reputation > > of the goto statement, but unfortunately I can't find it, as his > > other hobby is astrophotography, and there is apparently a species > > of computerized telescope called GoTo.. and a Google search is > > clogged with such results. > > > > Ah, here it is: > > http://www.covingtoninnovations.com/michael/blog/0509/index.html#050 > > 918 > > > > and he points to Steve McConnell's page at > > http://www.stevemcconnell.com/ccgoto.htm > > > > > > > > > > > > On 6/20/06, Mike Andrews <[EMAIL PROTECTED]> wrote: > > > No, I've not considered it. I'd rather set a flag variable to > > > make it > > work > > > rather than do anything with goto. > > > I just believe it's bad programming practice to use goto's. > > > > > > Thanks, > > > Mike > > > > > > > > > On 6/20/06, Toulakis, Dimitrios (RESC) < > > [EMAIL PROTECTED]> > > > wrote: > > > > > > > > Hi Mike, > > > > > > > > Have you considered using the goto statement? > > > > > > > > Cheers,Dimitrios > > > > > > > > -----Original Message----- > > > > From: Discussion of advanced .NET topics. > > > > [mailto:[EMAIL PROTECTED] On Behalf Of Mike > > > > Andrews > > > > Sent: Tuesday, June 20, 2006 3:49 PM > > > > To: [email protected] > > > > Subject: [ADVANCED-DOTNET] Exit Do... > > > > > > > > Guys... > > > > > > > > I know that break; is essentially the same as a VB Exit Do. > > > > > > > > However... > > > > > > > > If I'm inside a switch statement, is it possible to exit the Do loop? > > > > > > > > Thanks, > > > > Mike > > > > > > > > =================================== > > > > This list is hosted by DevelopMentor(r) http://www.develop.com > > > > > > > > View archives and manage your subscription(s) at > > > > http://discuss.develop.com > > > > > > > > =================================== > > > > This list is hosted by DevelopMentor(r) http://www.develop.com > > > > > > > > View archives and manage your subscription(s) at > > > > http://discuss.develop.com > > > > > > > > > > =================================== > > > This list is hosted by DevelopMentor(r) http://www.develop.com > > > > > > View archives and manage your subscription(s) at > > http://discuss.develop.com > > > > > > > =================================== > > This list is hosted by DevelopMentor(r) http://www.develop.com > > > > View archives and manage your subscription(s) at > > http://discuss.develop.com > > > > =================================== > This list is hosted by DevelopMentor(r) http://www.develop.com > > View archives and manage your subscription(s) at > http://discuss.develop.com > =================================== This list is hosted by DevelopMentor(r) http://www.develop.com View archives and manage your subscription(s) at http://discuss.develop.com =================================== This list is hosted by DevelopMentor® http://www.develop.com View archives and manage your subscription(s) at http://discuss.develop.com
