Force a variable substitution in expression

Hello,
I have a function that creates an expression object with some variables
substituted e.g

foo <- function(s){
  expression({
    v <- s
    print(v)
  })
}

Thus foo returns an expression, however the expression has the symbol 's'
contained within it and thus returns an error when eval'd e.g

x <- foo(10)
eval(x)
Error in eval(expr, envir, enclos) : object 's' not found

Q: How do I force a substitution so that the returned expression has the value
of 's' 'hardcoded'  in it e.g

foo(10)

returns

expression({
  v <- 10
  print(v)
})
  

The substitute() function can do it, but the bquote() function is the most
convenient:

foo <- function(s) {

+ ? bquote(expression({
+ ? ?v <- .(s)
+ ? ?print(v)
+ ? }))
+ }

foo(10)

expression({
? v <- 10
? print(v)
})

Duncan Murdoch