How to check if data structure is a collection or a list in TCL

Question

How do i perform a check like this?

if {} {
// code if it is collection
} else {
//code for list
}

Do you creatively use sizeof / llength and prevent that from failing? or there's a native command that does this cleanly?

Answer 1

A collection is not standard to Tcl, but is a type of object available in Synopsys design tools.

If you are referring to Synopsys collections, all collection have a string representation like _sel123 or _sel456. You can check this:

if {[regexp {^_sel\d+$} $obj]} {
    # $obj is most likely a collection
} else {
    # $obj is something else
}