passing arrays to functions in tcl. Only upvar?

Question

As far as I understand, in tcl if you want to pass a named array to a function, you have to access the upper scope of the caller via the upvar command within th

Answer 1

As Michael indicated, there are several ways, plus a wiki page that discusses it. Just to have some of that information here, some options are:

By Upvar

proc by_upvar {&arrName} {
    upvar 1 ${&arrName} arr
    puts arr(mykey)
    set arr(myotherkey) 2
}
set myarr(mykey) 1
by_upvar myarr
info exists myarr(myotherkey) => true

• results in changes to the array being seen by the caller

By array get/set

proc by_getset {agv} {
    array set arr $agv
    puts arr(mykey)
    set arr(myotherkey) 2
    return [array get arr]
}
set myarr(mykey) 1
array set mynewarr [by_upvar myarr]
info exists myarr(myotherkey) => false
info exists mynewarr(myotherkey) => true

• results in changes to the array being seen by the caller
• similar mechanism can be used to return an array