Hi Marius,
I think you're right in that len($input_type.input_bam) is inconsistent, we can implement __len__ for the collection case, but that is not done yet.
ThumbsUp! Would be for the tool developer convenience.
That said, unless your example is a toy example for a more complex scenario the switch seems unnecessary, a multiple="true" data paramater can take either multiple datasets or a collection.
You are right, still you could replace the list with a paired list or list list. Cheers, Matthias -- ------------------------------------------- Matthias Bernt Bioinformatics Service Molekulare Systembiologie (MOLSYB) Helmholtz-Zentrum für Umweltforschung GmbH - UFZ/ Helmholtz Centre for Environmental Research GmbH - UFZ Permoserstraße 15, 04318 Leipzig, Germany Phone +49 341 235 482296, m.bernt@ufz.de, www.ufz.de Sitz der Gesellschaft/Registered Office: Leipzig Registergericht/Registration Office: Amtsgericht Leipzig Handelsregister Nr./Trade Register Nr.: B 4703 Vorsitzender des Aufsichtsrats/Chairman of the Supervisory Board: MinDirig Wilfried Kraus Wissenschaftlicher Geschäftsführer/Scientific Managing Director: Prof. Dr. Dr. h.c. Georg Teutsch -------------------------------------------