This came up when I was building a tcl/tk application for running linux commands and capturing the output. I had an entry widget where I was inputting the commands and I wanted to add history alike shells. Johannes Kuhn helped me to build the history function and I added the history to be circular (like a circular linked-list). Here is proc:
proc histwalk i {
incr ::eventcnt $i
if {$::eventcnt == [history nextid]} {set ::eventcnt 1}
if {$::eventcnt == -[expr [history nextid]-1]} {set ::eventcnt 0}
set ::(.entry,stdin) [history event $::eventcnt]
}To this procedure you need to add the bind statements:
bind $entrywidget_textvariable <Return> { history add $stdin }
bind $entrywidget_textvariable <Up> {histwalk -1}
bind $entrywidget_textvariable <Down> {histwalk 1}This is much more simple than An entry with a history.