2013/1/2 J. P. L. Mart��n <arguser@gmail.com>:
> Another question, when I try this:
>
> Prestamo database collect: [:x | x id,' ',x idMaterial]
>
> I get Receiver of "," nil. How do I solve it?
You probably have one or more elements in the collection returned by
"Prestamo database" whose id's are nil.
Then you're sending #, to a nil element.
I would ensure all elements have an ID, or better than that I would
delegate the printing responsibility to the element itself.
It is:
Prestamo database collect: [:x | x printIdAndMaterial]
This way the testing of a nil id is done by the receiver.
Regards,
Esteban.