[Ktechlab-devel] a matter of style

[P Zoltan]

On Mon, 07 Dec 2009 13:35:03 +0100, Julian Bäume <julian at svg4all.de> wrote:

> hi again,
> I want to have short input on which iterators to use. Qt provides both,  
> STL-
> and JAVA-style iterators. Here an example:
> java-style:
>     QStringListIterator it(route);
>     QPointF p;
>     p.setX(it.next().toDouble()*8);
>     p.setY(it.next().toDouble()*8);
>     moveTo( p );
>     while (it.hasNext())
>     {
>         p.setX(it.next().toDouble());
>         p.setY(it.next().toDouble());
>         p*=8;
>         lineTo( p );
>     }
>
> same code with STL-style:
>     QStringListI::const_iterator it = route.constBegin();
>     QPointF p;
>     p.setX((*it++).toDouble()*8);
>     p.setY((*it++).toDouble()*8);
>     moveTo( p );
>     while ( it != route.constEnd() )
>     {
>         p.setX((*it++).toDouble());
>         p.setY((*it++).toDouble());
>         p*=8;
>         lineTo( p );
>     }
>
> which one should we use? There is now speed-impact of one over the  
> other. Just
> a matter of taste.
>
> When iterating the whole list, I personally prefer the foreach macro,  
> like:
>     foreach (QVariant component, m_model->components())
>     {
>         if (component.canConvert(QVariant::Map)) {
>             addItem( new ComponentItem( component.toMap(), m_theme ) );
>         }
>     }
> Is it okay? Or should we use another method, to iterate over every item  
> in a
> list. (alternatives are: for-loops in combination with List::size() or
> iterators)
>
> I know, we have talked about that, earlier, but IMHO, we didn't agree on
> anything, yet. At least, I'm not aware of it. We should specify these  
> things
> in the wiki.. and I'm willing to go through the code and change  
> everything
> according to our agreements. This doesn't have to be done, right now, I  
> just
> want to produce new code according to our agreements.
>
> My votes for the record:
> java-style iterators and foreach-macro, when possible

  +1, the STL style is not my favorite

  foreach is something new for me, so I don't have a string opinion about  
that. Note that instead of that while(), a for() could be also used in  
java style code:

   for(QStringListIterator it(route); it.hasNext(); ??? ) { ... }

  Where do you increment that iterator? It's strange.

  Note that there is a coding style page in the wiki, so these discussions  
can be noted there.

>
> bye then
> julian