Virtual Feed Shortcomings

[XtremeOwnageDotCom]

Migrated from #1660

I was working on creating a feed to display the amount of "self-produced" energy used at my house per day. The formula is pretty simple.

x = grid_energy_in_d: 9.4
y = load_energy_d: 31.1

p = 100 - ((x * 100) / y)

But, while trying to implement-

It became pretty apparent the ability to subtract the value from 100, doesn't appear to be easily possible. As well, you cannot use a virtual feed, inside of another virtual feed.

Originally posted by @XtremeOwnageDotCom in #1660 (comment)

A few potential solutions:

1. Allowing virtual feeds to reference other virtual feeds.
2. Allowing math operations to be reordered.

ie, instead of X - 1, allowing 1 - X.

[TrystanLea]

Thanks @XtremeOwnageDotCom

Reorganising the equation gives us a solution that can work with the existing implementation:

p = (((x*100)/y)-100)*-1

Not to say that we shouldn't explore the other solutions as I can see benefits to both.

[XtremeOwnageDotCom]

I personally think both solutions have other differing use-cases which may benefit others as well.

I can see lots of intricate capabilities being introduced by allowing nested virtual feeds.

For my example solution, I did previously resolve it in the way you described- But- still wanted to make sure to give a useful idea for future development.

[TrystanLea]

Ok sure, I will take a look at nesting, ideally need something in the interface to detect recursion, that shouldn't be too difficult.

[lo92fr]

Hello,

I take a look at point 1: "Allowing virtual feeds to reference other virtual feeds.".
It seems that it is already supported out of the box.

Just comment the following lines :
/*
if (parseInt(this.feedlist[z].engine) == 7) { //input context and virtual feed and process writes to feed?
continue; // Dont list virtual feed
}
*/
in function 'showfeedoptions':function(processid){ in file process_ui.js do the trick.

I test basic behaviors like adding/substrating virtual feeds together, and it seems okay.
Perhaps just to verify as TrystanLea said if we need to add some recursion test to prevent loops.

Best regards,
Laurent.

[chaveiro]

Recursion is supervised, any feed missbehaving is disabled for editing.

[lo92fr]

OK, perfect.
So is there something against the removal of these three lines so we can activate nexted feeds?