Hi everyone,
I have an [expr] object in an abstraction and I'd like to set the formula for the [expr] from the main patch, either at creation via argument or later with a message of sorts if possible.

This seems to work with simple formulas (the objects created have the appropriate number of inlets and the output is correct), however with more complex ones which might include spaces, the object won't create.

Does anyone have any suggestion on how to set expressions for the [expr] object after the creation, if indeed it's possible at all?

Thanks for your help.

@weightless Just a quick note: If you are sending the expression and the parameters into the abstraction, you could also just do the calculation in the main patch and send the result into the abstraction... just a thought...

@ingox the problem with $0 here is that I'm writing the expression in full in the abstraction's arguments, and then inside the abstraction I'm getting all the arguments as a list of symbols and therefore $0 gets copied as-is, and so the expr object ends up with the name 'table$0', and $0 gets substituted with the unique identifier of the abstraction, not the parent patch. The only way I can think of to do it right now is thus:

And yes, it sounds like a lot of trouble to go to when I could just do the calculation in the parent. I'm trying to implement something in the vein of what's described in the paper Chaos Melody Theory by Elaine Walker, and I'm going for a modular setup here where I'm envisioning using lots of abstractions, each with it's formula that can also be changed on the fly (via external message), has an internal feedback of sorts and writes the last n states to a table that can be referenced by other abstractions.

Perhaps this is the wrong way to go about it, it sure seems to most immediate and at least I've learnt something about the [expr] object and the iemguts library!

@weightless Thanks for explaining, sounds interesting. And yes, regarding $0 the way you described would be the way to go, using table$1 as part of the creation argument. Best wishes

@ingox Thank you for your help. I'll post the patch when it's fully working and cleaned up.

@weightless @ingox
You guys lost me about 3 posts ago, but can't tell from what I saw in your shares the idea below (image). But it's one way to put $0 into messages: via pack. If you'll already got this, then please forgive my ignorance of y'all's concerns.

Also, found out how to include commas (as you mentioned ingot via [list tosymbol]) and added it to my "-extended version" and include it here in case anyone wants the comma-included version, (I apologize for the oversight on my part).

abs_expr_gen_extended.pd
abs_expr_gen_extended-help.pd

Peace,
Scott

@weightless [bytes2any] from the Moocow library is the same as [list tosymbol] but works with $0.

@LiamG That's good to know thanks, although in this particular situation I think it was a problem of using the syntax "$0-" inside [expr], and of addressing the wrong $0, so to speak.

I'd just have a send and receive in my abstraction, and then have the same sends and receives outside in my parent patch, with the expr

exprSending.zip

here's a better version of what i just posted, without the send/receives
exprSending.zip

@mod This is a great solution, thank you. Here is modified to what I needed it to do:

expr.send.zip

It would've been nice to have been able to change the expression by sending a message but as it turns out it's very complicated indeed for what it is, and this will do nicely.

Thanks everyone for your help.

@weightless HOT!

I have updated the patch with a help file, now the last states of a specific object are accessible by addressing them in chronological order (0 = last state, 1 second to last etc.)

expr.cell.zip

I'm six years late to the conversation, but I'm adding my own contribution because this is the page that I found in the search engine when looking for "setting [expr] dynamically". Perhaps others will find it here.

calc.zip