How should one think of the order of non-reactive shiny server commands?

[UserSam]

In the Mastering Shiny book it is said that

It’s important to understand that the order your code run is solely determined by the reactive graph. This is different from most R code where the execution order is determined by the order of lines.

So why does the following Shiny app

library(shiny)

ui <- fluidPage(
  
)

server <- function(input, output, session) {
  print(1)
  print(2)
  
}

shinyApp(ui, server)

output to the console first 1 and then 2 ?
And why does it output these values only once, and not an infinite number of times?

[nirgrahamuk]

Your code doesnt define any reactive objects nor link them in a reactive graph.
The Mastering Shiny book is really excellent in my opinion.

[UserSam]

Right, I should have asked more precisely - how should one think of the order of non-reactive shiny server commands ? Are they run in sequence? Only once?

P.s. Now updated in the title and added "non-reactive"

[nirgrahamuk]

yes, they run in sequence like an r script, the server code is run line by line.
any reactive code in there can contribute to setting up the reactive graph, and non reactive code just runs when its encountered.

[UserSam]

@nirgrahamuk

yes, they run in sequence like an r script, the server code is run line by line.

However, in a module, if the last statement is a return statement, it does not get executed immediately, in the sense that the module does not finish the execution when the return statement is evaluated.
Why?

[nirgrahamuk]

a module is reactive code and so lazy and would only be evaluated if some other reactive element needed it to paint , or was forced like an observe