[development] easy way to check if a value has changed (nodeapi)

[Hans Langouche]

Hi there,

I'm working on a (node) profile system that has a checkbox to allow 
people to be informed by postal mail.  If checked the system sends a 
mail with the details to a certain email address.  Of course this email 
shouldn't be sent every time  the profile is updated, but only when the 
checkbox was previously unchecked (if it was checked allready, nothing 
should happen).

For the moment I'm thinking of creating a second (hidden) value to which 
I compare on 'update' and sync with the actual value after the check.  
But I'm thinking there must be an easier way, but can't find it in 
documentation or by inspecting $node on 'update'.

Tnx,

HnLn