Debugging
The rapid turnaround with Tcl coding means that it is often sufficient to add a few puts statements to your script to gain some insight about its behavior. This solution doesn't scale too well, however. A slight improvement is to add a Debug procedure that can have its output controlled better. You can log the information to a file, or turn it off completely. In a Tk application, it is simple to create a text widget to hold the contents of the log so that you can view it from the application. Here is a simple Debug procedure. To enable it you need to set the debug(enable) variable. To have its output go to your terminal, set debug(file) to stderr.
Example 13-12 A Debug procedure.
proc Debug { args }{ global debug if {
