Tcl features
The previous chapter introduced the basics of the Tcl language. We learned the basics of strings, lists, dictionaries, and integer and floating-point numbers. This section introduces some of the more advanced Tcl features— working with the time and date, data, namespaces, and stack frames.
Learning some of these features is required if you wish to understand and use Tcl and its features in a better way—especially meta programming, which can be used to create our own syntax and alter a program's flow control. This is one of Tcl's powerful features.
Working with time and date
When writing applications in Tcl, we'll often need to work in the context of date and time. One example is reading a file's access time, another one calculating how much time is left until, for example, next Sunday at 4 AM. Tcl uses the Unix timestamp for all date and time manipulations. This is a common approach which assumes that all dates and times are specified as a number of seconds since midnight on the...
