[pmwiki-users] Calculated PTV in forms

[kirpi at kirpi.it]

I have a form which was done starting from Fox Contacts[1].
Whereas straight text inputs work smooth, I could not find the right
way to set calculated PTVs.
I tried to model the form by following this advice[2] yet it seems
that (probably) the way I write PTVs inside the expression is not
right. Yet I tried all the variations I had in mind.
As an instance, this form

  Number: (:input text name=$:Number:)
  Sum_example: (:input hidden name=$:Sum_example value="{$$(add 7
{$:Number} {*$:Number} {=$:Number} {$$Number} {$$:Number} {{$:Number}}
{{*$:Number}} {{=$:Number}} {{$$Number}} {{$$:Number}} 5)}":)

always stores 12 in the resulting page, which to my eyes seems to mean
that the whole process is good for hard coded numbers but not
variables.
Where am I wrong, please?

Thanks!

Luigi

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[1] http://www.pmwiki.org/wiki/Cookbook/FoxContacts
[2] https://www.mail-archive.com/pmwiki-users@pmichaud.com/msg13549.html