Question

What is the proper way to initialize an empty array in Tcl?

I have the following code (simplified):

proc parseFile {filename results_array} {
    upvar $results_array results
    set results(key) $value
}

set r1 {}
parseFile "filename" r1

and I get the error:

Error: can’t set “results(key)”: variable isn’t array

Answer 1

You don’t initialize arrays in Tcl, they just appear when you set a member:

proc stash {key array_name value} {
    upvar $array_name a
    set a($key) $value
}

stash one pvr 1
stash two pvr 2
array names pvr

yields:

two one