When I send "clear" into the right inlet of [list cat], and then try to re-populate the list by sending something into the left inlet, pure data crashes.

Does this happen to anyone else?

It's a Purr Data class. In Pure Data Vanilla it's a line in a todo list.

@pure_datum Yep, it's a double free error. Perusing the source code I also noticed an "off-by-one" error when sending a non-list message to the object (a.k.a. the "anything" method).

Fixes are in the works:

https://git.purrdata.net/jwilkes/purr-data/merge_requests/283

(It will eventually produce some testing installer binaries if you follow that pipeline link, click on your OS and then click the "Download Artifacts" button. Or you can just wait for the next release)

Keep in mind that [list cat] sends output on each concatenation. So for optimal performance with larger lists you'll probably want a [spigot] below it that only opens once you are finished concatenating.

it seems [list cat] in Purr Data is similar to [list store] in Pd Vanilla. How is it different? BTW, I don't see [list store] documented in Purr Data.

Actually, better put, it seems [list cat] in Purr Data is just a limited version of [list store], which can append, prepend and do more things in Pd Vanilla. So they're very different, cause [list store] is more powerful, so it just seems that [list cast] is superfluous. So when I ask how different they are, it was more of a rhetorical question... I see now that I tested that there are different design choices, where [list cat] keeps outputting values when appending. I personally think it makes more sense the way this is handled in [list store], where you get the list you want in the end with a bang.

BTW, I don't see [list store] documented in Purr Data.

The class exists, it just wasn't listed in the help patch. It is now.

Also, I just saw that [list cat] wasn't reentrant. It will be in the next release.

not sure if you've also documented [list fromsymbol] and [list tosymbol] as well

not sure if you've also documented [list fromsymbol] and [list tosymbol] as well

Yes, I have.

I did a little testing on my Chromebook for accumulating lists of 10, 100, and 1000 floats with [list cat], [list store], [list prepend]x[t a], and "add2 $1" with a message box.

• [list store] is the fastest, but message box accumulation has pretty close performance to it
• [list prepend]x[t a] is the slowest with [list cat] the 2nd slowest
• all require memory allocations above 100 elements which increase their worst-time performance

So I'd say [list cat] is there mostly for backward compatibility at this point.

BTW-- I haven't tested it, but I'd bet that [list split] is significantly faster than using the "get" message with [list store], especially for large lists.

@jancsika [textfile] seems even faster: https://forum.pdpatchrepo.info/topic/10556/vanilla-list2symbol-abstraction-pd-0-47/9

Thanks for looking into that and clarifying @jancsika. And thank you @porres for pointing out the [list store] option.

@Jona [textfile] uses the same data structure underneath as a message box. So the performance for accumulating a list should be about the same as a message box. But I haven't tested it.

@jancsika thanks, interesting to know that they use the same data structure. in the link from my last post is a test.