Passing multiple lists of unspecified length to a program

Question

I would like to create a Stata program that takes multiple lists of unspecified length as arguments. However, I don't know how the program can distinguish between the lists once they're passed in.

For example, I'd like to be able to do something like:

prog myprog
args list1 list2
{something with list1}
{something with list2}
end

loc list1 a b c
loc list2 x y z
myprog `list1' `list2'

loc list1 a b c d
myprog `list1' `list2'

The two solutions I've been thinking about are:

1. Creating additional macros specifying the length of each list and passing those in as well
2. using a delimiter between lists

Neither is very difficult, but I would think there's a simpler way to do this.

I'm using Stata 13 for Windows.

Answer 1

The following works for me:

program define myprog
syntax, list1(string) list2(string)

display "`list1'"
display "`list2'"
end

local lista "a b c d"
local listb "e f g h"

myprog, list1(`lista') list2(`listb')

or:

capture program drop myprog
program define myprog

tokenize `0', parse(";")

local list1 `1' // optional
local list2 `3' // optional

display "`list1'" // or "`1'"
display "`list2'" // or "`3'"
end

local lista a b c d
local listb e f g h

myprog `lista';`listb'