On May 20, 2018, at 17:04, Andrew Moore wrote: > On May 20, 2018, at 8:23 AM, Ryan Schmidt wrote: > >> Why is macports_version a proc and not an option? > > To make it read-only? It seems procs and trace are Tcl’s way of defining constants. Variables can be easily made read-only. We already have an xcode_version variable.