Question

I have a “flat” Tcl list. Now I want to append a new element as a child to one of the existing elements. How can I do this?

This is what I tried:

[ lindex $flights $i ] [ lindex $flight 0 ] ]

I try to add an element form the list “flight” to an element of the list “flights”. The element $i in the flights list already exists.

I might be running against Tcl syntax as I’m new to Tcl.

Thanks for your help.

Answer 1

You can use lset to replace an element of your list with a new list. http://www.tcl.tk/man/tcl8.5/TclCmd/lset.htm The first element of the new list will be the old element, the 2nd element will be its child. Here’s an example:

% set flights [list a b c d e]
a b c d e
% set i 1
1
% lset flights $i [list b child]
a {b child} c d e
% lindex $flights 1
b child
% lindex [lindex $flights 1] 1
child
% lindex [lindex $flights 1] 0
b