refresh behavior in Interface

Question

I want to know the internal mechanism of local variable refreshing in an interface. When a local variable is refreshing, what is the underlying logic of the behavior? Is all code re-executed? Can you give me a conclusion and provide a demo to prove the conclusion.

Soma · Answer

Appian had concepts of load() and with(), 
 If you use load(), the code engulfed by load will get evaluated only once. A local variable's value is only calculated the first time the expression is evaluated and is then loaded back into the expression each time the expression is evaluated again within the same context 
 If you use with(),it recalculates the local variable values after interactions. This recalculation always happens, even if the interaction's updates could not have impacted the variable's value 
 localVariables() can implement the functionality of load and with function for each local variable initialized using various refresh options in the a!refreshVariable function. 
 Please read through this for more related information 
 docs.appian.com/.../SAIL_Performance.html

Soma · Answer

Play around the code to verify a!localVariables(
 local!counter:0,
 local!randomValue:a!refreshVariable(
 value: rand()
 /*refreshInterval: 0.5*/ /*Refresh every 30 seconds*/
 /*refreshOnReferencedVarChange: local!counter*/ /*Refresh when value of counter changes. Click on Add and see the change*/
 /*refreshAlways: true */ /* Refresh always*/
 ),
 {
 a!linkField(
 links: a!dynamicLink(
 label: "Add",
 saveInto: {
 a!save(
 local!counter,
 local!counter+1
 )
 }
 )
 ),
 a!textField(
 value: local!randomValue
 )
 }
)

Mike Schmitt · Answer

edwardc8281 said: I want to know some more underlying mechanisms or principles. 
 The underlying mechanics are not public and not published by Appian as far as I know. We know only what the official docmentation tells us (and what we can infer from experimentation). 
 What is your use case / what are you trying to accomplish?