You'll be glad to know! [modified]

[Super Lloyd]

Ok, maybe I should say what I did, so maybe an anti-goto purist can give me tips on how to write goto-less nice code in such circumstances... (or become less anti goto) so here we go, that's what I wrote (veil your eyes, code in the lounge!)

for(...)
{
avar = calculation()
if(avar == someValue)
goto doStuff;
avar2 = someOtherCalculation();
if(avar2 == someValue2)
goto doStuff;
continue;
doStuff:;
localVar.UpdateNicely();
}

A train station is where the train stops. A bus station is where the bus stops. On my desk, I have a work station.... _________________________________________________________ My programs never have bugs, they just develop random features.

[Dalek Dave]

Repost! :)

------------------------------------ I will never again mention that I was the poster of the One Millionth Lounge Post, nor that it was complete drivel. Dalek Dave CCC League Table Link CCC Link[^]

[AspDotNetDev]

Delete this post before everybody sees and you are shamed!

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[Luc Pattyn]

You really should read part 2 of your Language Reference Manual, in particular the chapters on logical operators and short-circuitry.

for (...) {
if (calculation()==someValue || someOtherCalculation()==someValue2) localVar.UpdateNicely();
}

Readability is the key concern here. :)

Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles] Nil Volentibus Arduum

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[Dalek Dave]

Early 80's programming is in my blood! I just can't let go of them goto statements :)

------------------------------------ I will never again mention that I was the poster of the One Millionth Lounge Post, nor that it was complete drivel. Dalek Dave CCC League Table Link CCC Link[^]

[Dalek Dave]

That's actually a nice bit of code. I have much to learm :sigh:

------------------------------------ I will never again mention that I was the poster of the One Millionth Lounge Post, nor that it was complete drivel. Dalek Dave CCC League Table Link CCC Link[^]

[Peter_in_2780]

How about

for(...)
{
avar = calculation()
if(avar != someValue)
{
avar2 = someOtherCalculation();
if(avar2 != someValue2)
continue;
}
localVar.UpdateNicely();
}

The point is basically that

if (something)
goto somewhere
more_stuff;
somewhere:

is equivalent to

if (!something)
more_stuff;

and you've just got two of them nested. Cheers from one who thinks coding standards are generally a good thing but do not represent ultimate authority. Peter

Software rusts. Simon Stephenson, ca 1994.

[Super Lloyd]

well, I wanted to use some simple pseudo code, but the statement "var1 = calculation()" is really a multi inner variable multiline statement with a more complex statement. I guess I can replace it with a private static variable with heaps of ref variable just or the sake of writing such statement as you sugest, but I won't!

A train station is where the train stops. A bus station is where the bus stops. On my desk, I have a work station.... _________________________________________________________ My programs never have bugs, they just develop random features.

[AspDotNetDev]

No excuse!

for(...)
{
if(calc() == v || calc2() == v2)
{
localVar.UpdateNicely();
}
}

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[AspDotNetDev]

Dang, you beat me.

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[Super Lloyd]

Indeed that will do! :thumbsup: :) However.... I do prefer goto to multiple nested statement! ;P

A train station is where the train stops. A bus station is where the bus stops. On my desk, I have a work station.... _________________________________________________________ My programs never have bugs, they just develop random features.

[Luc Pattyn]

the advantage of a keyboard with a very short cable. :)

Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles] Nil Volentibus Arduum

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[Dalek Dave]

It's neater.

------------------------------------ I will never again mention that I was the poster of the One Millionth Lounge Post, nor that it was complete drivel. Dalek Dave CCC League Table Link CCC Link[^]

[Super Lloyd]

there is the matter of avoiding goto, but this is no big deal, the real challenge is to do it in aesthetic and readable way! Well, I guess it's a subjective matter... But just to give you better chance, here is the real code. I think goto is the most elegant / beautiful solution. I invite you to show me the beauty of avoiding goto! (Although.. being a subjective thing... well....) Here we go:

for (int i = max; i >= min; i--)
{
var v1 = new Vector2D(points[i > 0 ? i - 1 : points.Count - 1], points[i]);
var v2 = new Vector2D(points[i], points[i < points.Count - 1 ? i + 1 : 0]);
if (v1.SquareNorm <= MINL || v2.SquareNorm <= MINL)
goto RemovePoint;
v1 = v1.Normalize(); // divide by zero if test above fail
v2 = v2.Normalize();
var z = v1 ^ v2;
if (Math.Abs(z) <= minsin && v1 * v2 < 0)
goto RemovePoint;
continue;
RemovePoint: ;
points.RemoveAt(i);
if (points.Count < 3)
return null;
}

A train station is where the train stops. A bus station is where the bus stops. On my desk, I have a work station.... _________________________________________________________ My programs never have bugs, they just develop random features.

modified on Thursday, September 9, 2010 8:31 PM

[PIEBALDconsult]

Until I did some refactoring today I had a method with three return statements! :omg: (They were to avoid a goto to abort a nested loop.)

[AspDotNetDev]

The only acceptable place I've found for a goto is within a switch block. After all, the "labels" are already defined.

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[Luc Pattyn]

Well, the complexity of avar1 = someCalculation(); isn't relevant, you can do it upfront anyway. The complexity of avar2 = someOtherCalculation(); is what matters. If it can't be put in the middle of the if clause, I'd use a boolean flag, like so:

for (...) {
bool updateWanted=false;
if (calculation()==someValue) updateWanted=true;
else if (someOtherCalculation()==someValue2) updateWanted=true;
if (updateWanted) localVar.UpdateNicely();
}

and now you can easily expand line 4 (and 3) as required. :)

Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles] Nil Volentibus Arduum

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modified on Thursday, September 9, 2010 8:52 PM

[AspDotNetDev]

PIEBALDconsult wrote:

avoid a goto to abort a nested loop

I usually set some bool, break, then conditionally break depending on the value in the bool. Slows things down a bit, so a goto might be more acceptable in this case if speed is of significant importance and the inner loop does not have many iterations.

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[Super Lloyd]

see the code below! it can't be done upfront, as the first if will avoid as divide by zero in the second if! just for your benefit I post the code below again! Anyway, yes it can be done, but I found my way more readable... I guess it's too subjective for debate.. but I invite you to show me the new version:

for (int i = max; i >= min; i--)
{
var v1 = new Vector2D(points[i > 0 ? i - 1 : points.Count - 1], points[i]);
var v2 = new Vector2D(points[i], points[i < points.Count - 1 ? i + 1 : 0]);
if (v1.SquareNorm <= MINL || v2.SquareNorm <= MINL)
goto RemovePoint;
v1 = v1.Normalize(); // divide by zero if square norm is 0 (test above)
v2 = v2.Normalize();
var z = v1 ^ v2;
if (Math.Abs(z) <= minsin && v1 * v2 < 0)
goto RemovePoint;
continue;
RemovePoint: ;
points.RemoveAt(i);
if (points.Count < 3)
return null;
}

A train station is where the train stops. A bus station is where the bus stops. On my desk, I have a work station.... _________________________________________________________ My programs never have bugs, they just develop random features.

[Luc Pattyn]

it's like writing poetry, just keep scrapping the redundant bits until you start to like the result. Except you have to adhere to the original intentions... :)

Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles] Nil Volentibus Arduum

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