Some questions about recursion

hi all,am a beginner of vb coding in grasshopper,recently im focusing on how to use the VB compenent,but something i cant understand stopped me .

the files of rhino and gh i uploaded contains 2 VB componets. the 1st is recursion i practice which a line rotate and scale until its length reach some certain unmber i setted.

the export side is a list (of online), which contains every scaled line(i thought it should be!!!!0,but the truth is that it export some same lines,everyone of them is the last line scaled and rotated at the recursion stopping condition!!!

i cant explain how it happen ,so i try another VB component ,which export list that due to the recursion ,but its not the same as the first one.it sucsessfully exported a list contaned different numbers.

could someone tell me why this happen? 2 VB i used the same structure ,but they exported different!!

thank you !!!

sorry for my poor englinsh!~

Attachments:

11.3dm, 48 KB
11.gh, 4 KB

Replies to This Discussion

Permalink Reply by Yuan.T on January 6, 2013 at 8:00am

is there someone could explain this to me ?~

Permalink Reply by Hannes Löschke on January 6, 2013 at 4:07pm

OnLine is a reference type, if you add() this to a list, only a reference to the current instance will be saved in the list. You modify the ScaledLine object in the loop but the object instance will be the same every time you add it to the list. The modification will be applied in every loop.

A number is a value type. Value types will be copied directly to the list. This is why the second script works as you expected.

To add a unique Instance of the line to your list in every loop, you need to create a copy and add the copy: