[ImageJ-devel] Simplifying loops?

[Brian Selinsky]

What happens if next() is called without checking hasNest() first?

Would returning null or throwing an exception that could be caught and potentially ignored be reasonable?



On 06/14/10, Stephan Saalfeld  <saalfeld at mpi-cbg.de> wrote:

> Hi,
> 
> we implement java.lang.Iterator<T extends Type<T>> where next() returns
> T, so no, next() cannot return boolean, fwd() and back() might do that.
> In the coming changes, Image<T> implements java.lang.Iterable<T>, such
> that the Java language shortcut works:
> 
> Image< T > image;
> for ( final T : image ) {
>     // meat of the loop
> }
> 
> How's that?
> 
> Currently, Cursor<T> implements Iterable<T> such that you can do:
> 
> Cursor<T> cursor;
> for (final T : cursor ) ...
> 
> instead,  but that's less sensible and will not stay.
> 
> Best,
> Stephan
> 
> 
> 
> 
> On Mon, 2010-06-14 at 18:54 +0200, Johannes Schindelin wrote: 
> > Hi,
> > 
> > On Mon, 14 Jun 2010, Stephan Preibisch wrote:
> > 
> > > This is definitely something we could do as far as the linked iterators
> > > work. Right now we did not do that because it is quite often extra work,
> > > e.g. if you copy an image you need only one check instead of two:
> > > 
> > > cursor1, cursor2;
> > > 
> > > while ( cursor1.hasNext() ) 
> > > {
> > > 	cursor1.fwd();
> > > 	cursor2.fwd();
> > > 	// meat of the loop
> > > }
> > 
> > Ah, I see. Maybe just a shortcut
> > 
> > 	public boolean next() {
> >         	if (!hasNext())
> >                 	return false;
> >         	fwd();
> >         	return true;
> > 	}
> > 
> > to optimize for the common case?
> > 
> > Ciao,
> > Dscho
> > 
> 
> 
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